Eddie sez:

Let's start off this sometimes controversial topic with a few answers:

You really should plot. If you think all those electronic gizmos in that fancy cockpit of yours make plotting unnecessary, see: Why the Pilot is the Last Line of Defense.


Photo: Eddie Plots
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Everything here is from the references shown below, with a few comments in an alternate color.

Last revision:


Do You Have to Plot?

Legally speaking

This used to be a pretty ease case to make because It once said so, right here:


Photo: "The Rule," from an out of date version of FAA Order 8900.1, Vol 4, Ch 1, ¶4-80
Click photo for a larger image

That language also once appeared in AC 91-70, in the days before that advisory circular had any of the alphabet appended to it. Now here is what the FAA order says:


Photo: "The New Rule," from an out of date version of FAA Order 8900.1, Vol 4, Ch 1, ¶4-80
Click photo for a larger image

So now the requirement simply says "systematic cross-checking" in accordance with AC 91-70 and it doesn't tell you when that is required.

Practically speaking

If all you read was the current Oceanic and International Operations advisory circular, you would be led to believe plotting is optional:

[AC 91-70B, ¶] Up to now the only recommended method of cross-checking aircraft position in the oceanic airspace environment was manual plotting on a chart. However, a panel of aviation industry and FAA personnel completed an Operational Safety Assessment of methods for cross-checking oceanic flight navigation. The panel determined that an alternative to manual plotting, by which aircraft position could be checked through use of aircraft FMS-driven navigation displays and indications, would provide for an equivalent level of safety.

[AC 91-70B, ¶] Plotting your route on your chart will increase your situational awareness as you execute your trip through oceanic and remote continental airspace.

[AC 91-70B, ¶] You should use a chart, of appropriate scale, to provide yourself with a visual presentation of your intended route, regardless of your type(s) of long-range navigation system (LRNS). Plotting your route on your chart will increase your situational awareness as you execute your trip through oceanic and remote continental airspace.

If you have to do a "table top" with the FAA — one where they are considering giving you the authorization to fly oceanic through LOAs B036 or B039 — they will ask you to plot, so you are going to have to know how.

Why you should plot

In the old days — when we were entering latitude and longitude into an inertial navigation system that didn't understand named waypoints — the typical reason given for plotting was the one degree error.


Photo: The classic one-degree error
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People still make the one-degree error but we are more likely to hear about oceanic re-routes that crews missed or entered in error.

  • Oceanic Reroute — Reroutes are common and except in rare combinations of aircraft/controller CPDLC capabilities, will require crews to manually enter FMS waypoints. I often read about crews that somehow mishandled the data entry. Plotting could have saved them.
  • An FMS error — yes, these happen. A few years ago the FMS makers didn't all agree on what nomenclature was needed for half-degree latitude separation and the result was chaos. The pilots who plotted caught the error. Another cause, albeit rare, is a coding error that waited until the database was updated. The first airplane to fly the route when the new database went into effect was caught. I've caught two such errors, but both were over continental Europe, not oceanic.
  • Other "technical" errors. Navigation databases are incredibly complicated and with the complication comes the chance for errors. See Why the Pilot is the Last Line of Defense, below.

But what if I'm doing everything perfectly?

Just because you are doing everything "by the book" doesn't mean another aircraft's errors can't impact you. How is plotting going to save you from another airplane's error? Here is a scenario for you. Let's say you filed Mach 0.80 as did the airplane in front of you, but the airplane behind you filed M0.83. Shanwick Oceanic planned on all this by placing the minimum spacing between you and the lead aircraft and allowed extra space between you and the third. Now let's say there is an unforecast increase in the tailwind and all three airplanes start to miss their next forecast ETA. (You are early.) You and the third aircraft revise your ETAs, as required, while maintaining your filed Mach Numbers. The lead aircraft, however, slows down to avoid having to revise his ETA and there is a loss of separation between you and the lead aircraft. Shanwick will be asking for all three aircraft to provide their paperwork and having shoddy paperwork may implicate the wrong crew.


Photo: Mach Number Technique
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No matter the reason, I like to think of it this way. When you are flying domestically all of your airplane's wizardry is keeping you separated from other airplanes and air traffic control's radar is backing everything up. When you are flying oceanic you don't have ATC's radar to help you out. It is up to you to back up the airplane's computers.

Even if you've flown the route a hundred times (an example of a good pilot gone bad)

You don't know every quirk of your FMS and sometimes that can bite you. For example, the Gulfstream GV FMS originally had a 100 waypoint limitation; that's a lot of waypoints. Well, no, it isn't. It is easy to have more than 100 when flying through Europe. One of our TAG Aviation pilots in 2005 was an old pro at flying from London to White Plains, over and over again. On one of his trips they departed Italy instead. He simply downloaded the flight plan and headed west. The crew didn't plot, didn't check the FMS, and ran out of waypoints at 30° West longitude. At that point, the airplane turned directly to White Plains. How do you spell Gross Navigational Error? The North Atlantic powers that be referred the case to the FAA who referred the case to our standards group. The pilots in question did not fare well. Plotting would have saved them.

How to plot (the old fashioned way)

As we shall see later on, there are other methods that make all of this very easy, but you should know how to plot the old fashioned way because (a) the FAA will expect you to demonstrate if you are applying for the necessary LOA, and (b) it will help you understand what your automatic methods are doing and to detect any errors from those systems.

[AC 91-70B, ¶] Your chart should include, at a minimum:

  1. The route of your filed flight plan or currently effective route clearance.
  2. Clearly depicted waypoints using standardized symbology.
  3. Graphic depictions of all ETPs.
  4. Alternate airports.
  5. Proximity of other adjacent tracks.
  6. Note: For certificated operators, if OpSpec/MSpec A061 has been issued authorizing use of an Electronic Flight Bag (EFB) and the principal inspector (PI) has authorized “interactive plotting for oceanic and remote continental navigation,” the EFB application may be used in place of a paper plotting/orientation chart. The current edition of AC 120-76, Guidelines for the Certification, Airworthiness, and Operational Approval of Electronic Flight Bags, provides guidance for operators to develop associated EFB procedures. For part 91 operators, an EFB may be used, provided the criteria and considerations of the current edition of AC 91-78, Use of Class 1 or Class 2 Electronic Flight Bag (EFB), are observed.

How is a Common Plotting Chart Laid Out?

Apart from saying the chart should be north up, must be based on WGS-84 and mean sea level, the chart printers are pretty much given discretion on how to print their plotting charts.


Figure: Plotting chart layout, (Eddie's notes)

[ICAO Annex 4]

  • 2.1.7 Recommendation.— The charts should be True North orientated.
  • 2.15.1 True North and magnetic variation shall be indicated. The order of resolution of magnetic variation shall be that as specified for a particular chart.
  • 2.15.2 Recommendation.— When magnetic variation is shown on a chart, the values shown should be those for the year nearest to the date of publication that is divisible by 5, i.e. 1980, 1985, etc.
  • World Geodetic System — 1984 (WGS-84) shall be used as the horizontal (geodetic) reference system. Published aeronautical geographical coordinates (indicating latitude and longitude) shall be expressed in terms of the WGS-84 geodetic reference datum.
  • Mean sea level (MSL) datum, which gives the relationship of gravity-related height (elevation) to a surface known as the geoid, shall be used as the vertical reference system.

There are some basic guidelines you should know for the chart you are using:

  • The horizontal lines are "parallels of latitude," usually a line for every degree with a major line every five degrees.
  • The vertical lines are "meridians of longitude," with a line for every degree with a major line every five degrees.
  • Longitude and latitude are subdivided into 60 parts known as minutes and labeled with a single quote mark (').
  • Minutes are further subdivided into 60 parts known as seconds and labeled with double quote marks (").
  • Bedford (KBED) airport, for example is at 42°28'11.8" N, 71°17'20.4" W; which is pronounced "forty-two degrees, twenty-eight minutes, eleven point eight seconds north, seventy-one degrees, seventeen minutes, twenty point four seconds west.

More about this: Navigation: Coordinates.

How to Plot a Position

There are many techniques on how to do this correctly, here is mine:


Figure: Position plotting example, (Eddie's notes)

  • Ensure you are in the correct quadrant: In the north the latitudes increase as you go up, in the south they increase as you go down. In the west the longitudes go up as you head west, in the east the go up as you head further east. Locate the nearest five degree line in the general area of your point, in the example 30° N.
  • Locate the five degree line just above your latitude, in our example 35° N.
  • If your chart has one degree markings locate the nearest degree below your point, otherwise count the degree lines. In our example 33° N.
  • Count the tick marks between degree lines on the chart you are using. In our example there are six so we conclude each tick mark represents 10 minutes of latitude. Counting up four tick marks we identify 30°40' N latitude.
  • Notice that a line connecting 33°40' N 150° W and 33°40' N 160° W does not cross 33°40' N 155° W, it runs high. That's because the chart is a Lambert Conformal Projection which bends toward the poles. To get a more accurate position, we need to find the 33°40' point on the scale closest to our position.

Figure: Position plotting example, (Eddie's notes)

  • When dealing with longitude, we look for the nearest five degree line under our desired position, in our example 155° W.
  • Then we look for the nearest five degree line greater than our desired position, in our example 160° W.
  • We can now locate the nearest degree under our position, in our example 156° W.
  • Counting the tick marks, we see there are six so 30' of longitude will be three greater.
  • Unlike latitude, lines of longitude appear parallel between lines of latitude, so we can draw a line at 156°30' W between tick marks and it will remain accurate.
  • We then transpose our mark identifying 33°40' N to this line of longitude and viola, we have our position.

How to Plot a True Course

For a tutorial on headings, courses, variation, and the like, see: Navigation - Direction.

Understanding True versus Magnetic heading

Part of the plotting process is to check the courses in your FMS (which are almost always in Magnetic) against those on your charts (which are in True). To convert from True to Magnetic you need Variation.


Figure: Variation, (AFM 51-37, page 1-13)

[AFM 51-37, page 1-12.] The magnetic compass points to magnetic north. The angular difference between true and magnetic north is known as variation and it changes for different locations on the earth. Variation must be considered when converting true course, true headings, or true winds to magnetic direction.

If you need to convert, the formula is:

True + Variation = Magnetic

Where West Variation is positive and East Variation is negative

If, for example, you measure a True course of 090 on the chart and the nearest line of Variation is 10° East, the Magnetic course will be 090 - 10 = 080° (Because you subtract East Variation.)


Photo: Finding variation in JeppFD
Click photo for a larger image

If you don't have a paper chart, you may not find variation on the electronic chart. In JeppFD, for example, you need to select "VFR" from the chart type (left side of the accompanying photo), select the "Interstate 25" sign (right side of the accompanying photo), and zoom down to a fairly small scale. This works just about everywhere in the world except the North Atlantic, where variation magically disappears. For those of you without JeppFD and even for JeppFD users over the North Atlantic, your FMS should display variation for each waypoint.


Photo: Finding variation in a G450 FMS
Click photo for a larger image

Your FMS needs a database of worldwide magnetic variation and should be able to find a page that gives you access to that database. In a PlaneView cockpit (G450, G550), select "NAV" and "WPT DATABASE" and enter the point you want the variation. In the example photo, we see the variation is 14° West at 51°N 30° W.

Measuring Course

Figure: Jeppesen Plotter, (Eddie's collection)

A plotter is nothing more than a circular instrument designed to give angular differences between lines. A navigation plotter, such as the Jeppesen model shown, will typically have a hole in the center of a compass rose. To use:

  • Decide if you want the start, mid, or ending course. Most pilots will need the start course. For more about this, see: Start / Min / End Point Differences.
  • Place the hole in the center of the compass rose over a line of longitude near the desired point, in our example we've used 40°W which is also the longitude of our start point.
  • Align the line along the 0° mark to your desired course. You may find it helpful to insert your pencil or pen point in the hole while rotating the plotter to line up with your course.
  • Read the true course along the line of selected longitude, 085° in our example.
  • Note: You will have two choices aligned with the line of longitude, 085° and 275° in our example. In most cases it will be the number on top, but when dealing with courses near vertical it can be confusing. Always remember to give your answer a common sense check. In our example, we are headed to Europe and the answer should be generally easterly.

Measuring Distance


Figure: Dividers, step 1, (Eddie's collection)

[AFM 51-40, Page 5-8.]

  • One of the disadvantages of the Lambert Conformal chart is the lack of a constant scale. If the two points between which the distance is to be measured are approximately in a north-south direction and the total distance between them can be spanned, the distance can be measure on the latitude scale opposite the midpoint. However, the total distance between any two points that do not lie approximately north or south of each other should be be spanned unless the distance is short. All distances should be measured as near the mid latitude as possible.
  • In the measurement of long distances, select a mid latitude lying approximately half-way between the latitudes of the two points. By using dividers set to a convenient, reasonably short distance, such as 60 nautical miles picked off at the mid latitude scale, you may determine an approximate distance by marking off units along the line to be measures as shown [in the figure].
  • The scale at mid latitude is accurate enough if the course line does not cover more than 5 degrees of latitude (somewhat less at high latitudes). If the course line exceeds this amount or if it is crosses the equator, divide it into two or more legs and measure the length of each leg with the scale of its own mid latitude

If you have a set of dividers and a flat surface you aren't afraid to scratch, find the distance between waypoints is quite easy. First, place the points of the dividers on the start and end waypoints.


Figure: Dividers, step 2, (Eddie' collection)

Next, find a line of longitude near the course line. It is important to use a line of longitude about the same latitude as the course, since these will change over great distances. Each degree of latitude equals 60 nautical miles.


Figure: Post It Measuring Tool, (Eddie's notes)

If you don't have a set of dividers — do you really want to have such a sharp instrument in the cockpit? — you can construct your own with a PostIt note or other straight-edged paper. You will be accurate within a nautical mile if you do it this way:

  • Place the straight-edged paper along side the course. In our example, the PostIt note isn't long enough so we've used two, overlapping, notes.
  • Place a tick mark at the starting and ending waypoints.
  • Move the straight-edged paper to the nearest line of longitude at about the same latitude. Place one tick mark over a convenient line of latitude, 49°N in our example.
  • Read the distance from the ending tick mark, using 60 nautical miles per degree. In our example the distance covers at least 6° of latitude, which comes to 360 nautical miles. The mark goes further by a tenth of a degree, meaning another 10 nautical miles. We conclude the distance between waypoints is therefore 370 nautical miles.

Note: You can also determine the distance using a set of "10 Degree Tables," where we would see the exact distance is actually 369 nautical miles. (Our PostIt note was off by 1 nautical mile, or had an error rate of 0.27 percent, not bad.

More about this: 10 Degree Tables.

Start / Mid / End Point Differences


Figure: Starting vs Mid vs Ending Points, (Eddie's notes)

Your plotting chart is based on a Lambert Conformal projection, the lines of longitude converge near the poles. Except for the equator, the lines of latitude are not straight, they curve toward the equator. The measurement of your true course depends on where you place the center of your plotter and it does make a difference. In the figure shown, flying from 33°N 160°W to 33°N 150°W should, intuitively, require a 090° true course. The actual course, however, depends on what you want: the starting, mid, or ending course.

Most flight planning services offer either the starting or midpoint courses. Some pilots want to know what their initial course will be, others want the average course on the entire leg. It is a matter of personal preference.

I prefer using the starting course, since that is what the FMS will be showing prior to crossing the waypoint. (Following waypoint passage the course will update to reflect the "current" great circle route to the next waypoint. This course will constantly update as you progress, only reaching the midpoint course when you are actually at the midpoint.)

More about this: Navigation: Initial vs. Midpoint Course.

How to Determine a Magnetic Course

True Course plus Variation equals Magnetic Course . . .


Figure: Variation Example, (Eddie's notes)

To determine the magnetic course, you will need to add or subtract the variation:

  • Look for the nearest lines of magnetic variation on the chart before and after the midpoint and interpolate if necessary.
  • If the variation is West, add this value to the true course to determine magnetic course. If the variation is East, subtract this value from the true course to determine magnetic course:
  • TC + West Variation = MC
    TC - East Variation = MC

In our example, it appears our midpoint is very close to the "16°W" line of variation and no interpolation is necessary. Based on this we add 16 to our 270 true course and verify that our FMS and flight plan show a 286° magnetic course plus or minus a few degrees.

For a tutorial on magnetic variation, see: Navigation - Direction.

Note: It is not uncommon to find differences of 2 or 3 degrees in the magnetic course determined from a plotting chart and that reported in a computer flight plan. The magnetic variation changes over the years and your chart may be dated or hasn't been updated with the correct variation.

How to Determine the Position of a VOR Radial/DME

There are many ways to turn a VOR radial/DME into a latitude and longitude, the best of these may very well be inside your FMS. If you need to do this on a plotting chart, this method works well:


Figure: VOR/DME Plotting, (Eddie's notes)

  • Place the plotter hole over the VOR in question and your pencil point in the hole to hold the plotter centered over the VOR. (CON in our example.)
  • Find the nearest line of variation. (6° West in our example.)
  • Rotate the edge of the plotter to 360* in the northern hemisphere, 180* in the southern hemisphere, and then rotate toward the magnetic pole by the amount of the variation. (Rotate 6* to the west, in our example.)
  • Move your pencil from the center hole to the straight line of the plotter that describes the line to the magnetic pole, move the plotter so the straight edge connects that point to the VOR. Draw a line with a flag on it from the VOR in the direction of the pole. Label this line "360° Mag" if you like. (In our example the flag points slightly left.
  • Now return the plotter center hole to the VOR and rotate it in relation to your 360° Mag line by the number of degrees in the VOR radial. Draw a line as you did earlier by placing a tick mark, moving the plotter, and drawing the line. (In our example the line is 15° clockwise from the Magnetic north line.)
  • Determine the distance using the Distance Measuring techniques shown above. Place a tick mark on the VOR line. (015°/85 DME in our example.)
  • The latitude and longitude can be read directly from the chart using the Plot a Position techniques shown above. (55°15'N 8°25'W in our example.)

If you are doing this to check the accuracy of your FMS, you might have easier tools at your disposal. More about this: Navigation Accuracy Check.

When to plot

I think the practical answer to the "when do I have to plot?" question is whenever you don't have a backup to the space-based and inertial-based navigation. There used to be an actual answer in writing:

[FAA Order 8900.1 OUTDATED VERSION Volume 4, Chapter 1, Paragraph 4-80.A]

  • Plotting Procedures. Plotting procedures have had a significant impact on the reduction of gross navigational errors. There is a requirement to plot the route of flight on a plotting chart and to plot the computer position, approximately 10 minutes after waypoint passage. Plotting may or may not be required, depending upon the distance between the standard ICAO ground-based NAVAIDs.
    • Plotting procedures are required for all turbojet operations where the route segment between the operational service volume of ICAO standard ground-based navigational aids exceeds 725 NM.
    • Plotting procedures are required for all turboprop operations where the route segment between the operational service volume of ICAO standard ground-based navigational aids exceeds 450 NM.
    • The Administrator requires plotting procedures for routes of shorter duration that transit airspace where special conditions exist, such as reduced lateral and vertical separation standards, high density traffic, or proximity to potentially hostile border areas.
    • Any existing approvals that differ from the plotting requirements in this paragraph and Class II navigation procedures should be reviewed and revised as necessary. Direction and guidance is available from the navigation specialists in coordination with AFS-400.

What is the service volume of a navigation aid?


Figure: Standard High Altitude Service Volumes (Aeronautical Information Manual, Figure 1-1-1.)

You could have a navaid tuned and identified far outside its service volume, which means it doesn't count when making the plot / don't plot decision. Typical service volumes from [Aeronautical Information Manual, ¶1-1-8:

  • Standard High Altitude Service Volume between 18,000 and 45,000 ft: 130 nm
  • Standard Low Altitude Service Volume between 1,000 and 18,000 ft: 40 nm
  • Standard Terminal Service Volume between 1,000 and 12,000 ft: 25 nm
  • NDB HH Service Volume: 75 nm
  • NDB MH Service Volume: 25 nm

So the service volume of a qualified navaid answer isn't binding anymore, but it gives you an idea where you really should be plotting. (I like my earlier answer better.)

What about fixed airways?

I often hear from crews that want reassurance that there is no need to plot the routes between California and Hawaii because they are fixed and appear on their charts. They are wrong.


Photo: The Hawaii "Romeo" Routes
Click photo for a larger image

They are much more than 725 nm outside the service volume of the nearest navigation aid, they have to (and should) plot.

Alternatives to Paper

A liberal reading of AC 91-70B would lead you to believe that doing all of your "plotting" on the aircraft's navigation display should be adequate:

[AC 91-70B, ¶] You can use various additional techniques in order to verify that the correct points are loaded for your planned route. Verify the total route distance in your FMS against your master document to help find embedded mistakes. You should also cross-check course/headings and distances between each waypoint to ensure the FMS routing matches your master document. Referencing your plotting or orientation chart here can also be beneficial.

[AC 91-70B, ¶D.2.9.2] Ten Minutes After Waypoint Passage. Cross-check navigational performance and course compliance by one of the following methods:

D.2.9.1 The “plotting” method is appropriate for all aircraft navigation configurations.

  1. Verify your plotting/orientation chart reflects the currently effective route clearance.
  2. Plot your present latitude/longitude and record the time on your chart.
  3. You should plot your position using coordinates from the nonsteering LRNS.
  4. Investigate/take corrective action if your plotted position does not agree with your currently effective route clearance.
  5. Using the steering LRNS, verify the next waypoint is consistent with the currently effective route clearance.
  6. Verify your autopilot steering mode is in LNAV/VNAV or other appropriate mode to ensure steering to the next intended waypoint.

D.2.9.2 The “navigation display” method is appropriate for and available for use in aircraft equipped with an operable FMS:

  1. Confirm the aircraft symbol is on the programmed route on the navigation display (at smallest scale).
  2. Check system-generated cross-track deviation or similar indication of any deviation from the programmed route of flight.
  3. Using the steering LRNS verify the “TO” waypoint is consistent with your currently effective route clearance.
  4. Investigate/take correction action to address any anomalies or unexpected deviations.
  5. Verify your autopilot steering mode is LNAV/VNAV or other appropriate mode to ensure steering to the next intended waypoint.

After investigating a GNE in response to an FAA inquiry in 2005, I asked if this method of plotting was adequate and was told no. As late as 2018 I asked members of the FAA navigation branch and was told the same thing. You should not simply look at the navigation displays and see that your airplane is where it is supposed to be and consider your plotting chores complete. But you don't have to resort to a paper plotting chart, a plotter, and a sharp pencil. There are other methods that are easier and more accurate . . .

Plotting with an iPad

There are a few different ways to plot with an iPad, some good and some bad. But before we cover that, we need to cover something most of us have ignored since we got our very first iPad . . .

Is that iPad really legal for use in a cockpit?

Operating an iPad and a portable GPS receiver that is independent of the aircraft systems would seem to be the ideal crosscheck of your aircraft avionics. But is it legal? The basic regulation seems to indicate that it is, provided you can determine the device in question "will not cause interference with the navigation or communication system" of your aircraft. But how can you make that determination?

These rules were established in 1961 but were relaxed considerably in 2000 and again in 2006 with the release of Advisory Circular 91-21.1B which gave operators the latitude to allow the use of non-transmitting Personal Electronic Devices (PEDs) and gave some guidance on Transmitting PEDs and Medical PEDs. Operators were also given guidance on how to make these determinations. But no guidance was given for PEDs that receive GPS signals.

The latest version of AC 91.21-D cleared a lot of this up. The basic rule is that if your aircraft was certified with an onboard WiFi system, you are considered "PED Tolerant." Otherwise, you either have to get them tested (very hard to do) or restrict your use to ground taxi operations and cruise flight above 10,000 feet (easy to do).

So for the purpose of oceanic operations and plotting, the iPad and even a portable GPS unit are generally okay. (Operating commercially, you will need OpsSpec/MSpec/LOA A061.) If you are using your iPad (or other Electronic Flight Bag hardware) to view your airfield diagram during taxi, that's okay too. But if you want to use these devices for takeoff and landing, you have more work to do. More about all of this: Portable Electronic Devices.


Photo: Pilot Greg Bongiorno and his iPad on a Gulfstream G450
Click photo for a larger image

Aircraft Type Data Certification Sheet . . . Good to go.

If you are flying something that was certified relatively recently, you may find the aircraft's PED tolerance explicitly stated. This for the Gulfstream GVII-G500:


Photo: GVII-G500 PED Tolerance, from its Type Data Certification Sheet.
Click photo for a larger image

So if you are flying a GVII-G500, you are good to go. Most aircraft certified more than 5 years ago, such as my trust Gulfstream G450, will not have this statement. But that doesn't mean you are not PED tolerant, as we shall now see.

Airplane certified with a demonstrated tolerance for PEDs . . . Good to go.

[AC 91.21-1D, ¶7.2.1] Aircraft Designed and Certified PED Tolerant. Aircraft manufacturers with access to aircraft electronic system qualifications and aircraft radio receiver antenna installation data can easily demonstrate an aircraft meets the requirements of RTCA DO-307A. Operators may obtain statements of such demonstrations from an aircraft manufacturer to substantiate PED tolerance of the aircraft. Operators can also use the RTCA DO-307A methods in demonstrating PED tolerance of their aircraft. RTCA DO-307A separates demonstration methods for tolerance to intentional transmissions from PEDs versus tolerance to spurious emissions from PEDs. Aircraft with an FAA-approved system—such as an Onboard Mobile Telecommunications System (OMTS), Wireless Fidelity (WiFi), airborne access systems (AASs), or Network Control Units (NCUs)—are considered PED-tolerant for PEDs used with the installed system. If an aircraft model has demonstrated tolerance for both transmitting and non-transmitting PEDs, the operator may allow PED use during all phases of flight on this aircraft model.

If your aircraft is certified with one of the listed systems (OMTS, WiFi, or AAS), then you are "PED Tolerant" and can use PEDs during all phases of flight. Of course you will have a few precautions to take, like turning the cellular system off by using "Airplane" mode and making sure it is properly stowed for takeoff and landing, but you can use it in the cockpit for all phases of flight.

Airplane passes risk assessment . . . Good to go.

[AC 91.21-1D, ¶7.2.2] Aircraft Not Designed and Certified PED Tolerant. An operator may choose to conduct a safety risk assessment following the process in RTCA DO-363 if it 1) does not have a designed and certified PED-tolerant aircraft, and 2) chooses not to test its aircraft fleet types according to RTCA DO-307A or obtain supporting documentation from an aircraft manufacturer. The operator’s assessment must evaluate the avionics configuration of its fleet and failure modes of communication, navigation, surveillance, and other electronic systems with respect to electromagnetic interference. This assessment ultimately outlines mitigations and controls the operator needs to adopt to expand PED use into various phases of flight.

There are two phases to the risk assessment, as outlined in InFO 13010 Sup: "Back door" and "front door" assessment. "Back door coupling" refers to intentional radio frequency emissions from transmitting PEDs which can interfere with aircraft systems. Appendix B of InFO 13010 Sup provides instructions on how to determine if an analysis must be performed. Many aircraft have the necessary statement in their Type Certificate Data Sheet (TCDS) that allow them to assume the back door assessment is already completed. The front door assessment is much harder to determine and most operators will not be able to obtain such an assessment on their own.

Aircraft missing demonstrated tolerance or required assessment . . . Good to go for cruise flight only.

[AC 91.21-1D, ¶7.2.3] Aircraft Not Demonstrated PED Tolerant. If the operator has not demonstrated PED tolerance for their aircraft, they may allow PED operation during cruise flight. If interference to aircraft systems from PEDs is experienced during cruise flight, the devices causing interference should be isolated, and applicable conditions recorded. The device responsible for the interference should be turned off.

Unless your aircraft is PED tolerant or you have done an RTCA DO-363 risk assessment, this is what you are left with: you can only allow PED use during cruise flight.

[AC 91.21-1D, ¶8.1] Operator Procedures. If an operator allows PEDs aboard its aircraft or the aircraft being operated, procedures should be established to control PED use during aircraft operations. RCTA DO-363 section 7.5 and InFO 13010SUP provide further guidance on what to include in the operator’s policies, procedures, and training programs. In general, the procedures should address:

  1. PEDs approved for use onboard the aircraft;
  2. Times of approved PED operation;
  3. How and when PEDs must be secured or stowed;
  4. PED modes of operation used and not used;
  5. How and when to inform passengers of the aircraft operator’s PED policies and procedures; and
  6. How to manage scenarios such as suspected or confirmed electromagnetic interference, PED unit or battery smoke or fire, or other scenarios.

[AC 91.21-1D, ¶8.2] Passenger Communication. This paragraph outlines methods to inform passengers of permissible times, conditions, and limitations of PED usage. These methods may be accomplished through the departure briefing; passenger information cards; flightcrew, flight attendant (F/A), or prerecorded announcements; or other methods deemed appropriate by the operator. Operators should inform passengers of PED use restrictions, such as prior to departure, after takeoff (at 10,000 feet), prior to landing (at 10,000 feet), and after landing. For air carrier operations conducted under part 121 or 135, the limitations, at a minimum, should state the use of all such devices—except medical electronic devices such as heart pacemakers or portable oxygen concentrators (POC)—is prohibited during phases of operation when they could interfere with communication or navigation equipment onboard the aircraft or the ability of the flightcrew to give instructions in the event of an emergency. Methods of passenger communication may include:

  1. Procedures to terminate operation of PEDs suspected of causing interference with aircraft systems.
  2. Procedures for reporting PED interference to a responsible Flight Standards office.
  3. Procedures for cockpit-to-cabin coordination and cockpit flightcrew monitoring procedures.
  4. Procedures for determining acceptability of PEDs for operation aboard its aircraft. Acceptable PED identification should be clearly spelled out in oral departure briefings and by written material provided to passengers.
  5. Procedures for takeoff and landing preparation must be considered when allowing the PED operation during these phases of flight. Operators must recognize that the potential for personal injury to passengers is a crucial consideration, as well as the possibility of missing significant safety announcements during takeoff and landing. InFO 13010 and InFO 13010SUP provide guidance to address these considerations.

[AC 120-76D, ¶12] A part 91K, 121, 125, or 135 operator must have an EFB program authorized by the FAA in order to use EFB applications on either portable or installed equipment in flight operations. EFB program specifics (i.e., operating procedures, maintenance procedures, administrative procedures, and training modules) must be developed, as applicable, and be available to the FAA. FAA authorization for an EFB program will be granted upon successful evaluation of an applicant’s program operation.

Bottom Line:

It is up to the operator to determine if you can use that iPad and portable GPS during cruise flight, taxi before takeoff, and taxi after landing. Under 14 CFR 91K, 121, and 135, the operator is the company that controls the operation and have a program "authorized by the FAA" usually with OpSpec/MSpec/LOA A061. Under 14 CFR 91, it is you, the pilot.

Plotting on an electronic image of a chart (PDF or other photo-like image)

There are various vendors out there that will sell you a PDF chart the day of your flight that already has the relevant oceanic tracks plotted. Alternatively, some vendors will sell you a chart without the tracks for a little less money. In either case, it is up to you to plot your course, ETPs, and all other items just as you would on paper. This would seem to be the easiest way to transition from paper to plastic since you are doing the same thing only on an iPad. It is actually very difficult and frustrating for reasons that I hope to make clear.


Photo: Completed oceanic plotting chart example, annotated with GoodReader. (Click image for full size)

This method is easy enough but there are a few things that may not be entirely intuitive. Here are a few pointers:

  • You can use a plastic plotter on an iPad but the second you touch the screen with your hands, the position and scale of the map can change. Try a larger plotter and place it on the iPad in the correct position before making contact with the screen.
  • images

    Photo: iPad course measuring

  • Measuring distance is even harder because the scale is prone to change the second you make contact with the screen. We had our best luck with a pair of dividers with the pointy ends dulled with a file.
  • images

    Photo: Makeshift iPad dividers

  • Finding the exact longitude and latitude can be easier if you draw straight lines from the nearest scale, pick the intersection, then erase the lines.

This method of plotting on a PDF works but it isn't very accurate. Getting courses and distances will take a fair amount of time and can be frustrating. Placing your finger or stylus on exactly an exact latitude/longitude isn't easy. If you have access to a charting application, that is definitely easier, faster, and more accurate.

The remaining steps, such as plotting your position or doing a navigation accuracy check, are completed as you would with paper, just using the same steps to plot your route. We used this method for a few months in parallel with paper procedures. Paper was consistently faster.

Using an application-based plotting tool

I first looked into this in in 2015 and fully examined the process for a speech I gave to the 2019 NBAA International Operators Conference. The software I used was ForeFlight, Garmin Pilot, and JeppFD. Since then, several others have come on market that are quite good. In fact, I now use ARINCDirect exclusively because it is so much better. But that is a pricey program and they offer specific training should you decide to go that route. I'll detail the process for ForeFlight and JeppFD to show generally how it is done. You should look for application-specific instructions. (Even for the ones I am showing here, as they are sure to have improved since 2019.)

Understanding Latitude and Longitude Units of Measurement

As international pilots we all have an intuitive understanding of geographic coordinates from the days of Ferdinand Magellan:

  • The globe is divided by 360 degrees of latitude and longitude, measured from 0 to 180 going east and west starting at the prime meridian, and 0 to 90 degrees going north and back to 0 degrees going south starting at the equator in one direction and south back to north in the other.
  • Each one of those degrees is divided another 60 times into "minutes."
  • Each of those minutes is further divided another 60 times into "seconds."

More about this: Coordinates.

  • HDD°MM'SS" — You will often see these coordinates where the H is N, S, E, or W, with a degree symbol, a single quote, and a double quote. For example, N39°53'41" means 39 degrees, 53 minutes, 41 seconds North latitude. Your FMS doesn't do it this way and chances are your application software doesn't either.
  • HDD°MM.dd — Your FMS probably uses a different format that uses decimal minutes instead of seconds. For example, the earlier latitude would translate to N39°53.68 and might even appear as N39.5368. Confused? You can tell it is using decimal minutes and not seconds because the seconds are never higher than 59. Some applications also use the NDD°MM.dd format, which makes your plotting life easier.
  • HDD.dddd — Some applications use degrees and decimal degrees.

It is important to know which method your FMS, your Master Document, and your plotting software are using. You can not mix one method with the other without first doing some math or implementing provided translators. Let's say your Master Document show s your ETP is at N53°05.30, using the same format that your FMS uses, HDD°MM.dd. But now let's say your plotting software uses HDD.dddd. If you type in N53.0530, that will translate to N53°08.83.

You can do the math on your own if you have no other choice. To convert decimal values into minutes or seconds, multiply by 60. For example, the .83 minutes in the last example become (0.83) x (60) = 50 seconds. To convert seconds or minutes into decimal values, divide by 60. So 50 seconds becomes (50) / (60) = .83 minutes.

If you plotting application uses HDD.dddd, there is probably a way to automatically convert your inputs. In ForeFlight, for example, you can have it automatically change all your inputs into the needed NDD.dddd through the settings tab. Or you can have it make the conversion if you follow a particular format. Typing in your coordinate in the format HDDDMMS tells it your are using degrees, minutes, and decimal minutes. ForeFlight will do the translation for you, but when you examine the same point it will be in HDD.dddd format.

ForeFlight Example

Plotting your route

Photo: Copying the route
Click photo for a larger image

If you are using an interactive application to produce your plotting chart, you can cut and paste the route from either the application's master document or the PDF version of the master document. Press and hold any portion of the route until at least a portion of the route appears in inverse video. Then drag the start and end handles until the entire route is highlighted. Then select "Copy." You then go to the plotting application to the route entry appears, press and hold until you see a "paste" button.

To cut and paste your routing into ForeFlight you will first have to export the master document PDF file into ForeFlight. From that point you select the file from the bottom Documents tab.


Photo: ForeFlight, the documents page
Click photo for a larger image

At this point you select and copy the route as shown above under "Using an interactive application" by pressing on a part of the route, extending the copy handles until the route is highlighted, and the select "Copy" from the pop up menu.


Photo: ForeFlight, entering the route
Click photo for a larger image

Now select "FPL" from the top menu, "Clear" the old route if necessary, and then press and hold the Search window on top. You should be presented with the text you just copied, press to select.


Photo: ForeFlight, entering the route
Click photo for a larger image

The result should be your copied route.

Checking courses and distances

Once you've entered the route, pressing the FPL button brings up the flight plan which includes headings and distances:


Photo: ForeFlight example flight plan page.
Click photo for a larger image

Notice that this brings up headings not the courses. If ForeFlight has or has recently had access to the Internet, it will automatically download the winds and you will not be able to display courses. To get around this, tap the "Edit" button below the legs, then look for either "ETD" or a time which indicates the ETD. Tap the ETD and you will see a calendar. If you select a date at least 7 days away, the winds are zeroed and the NavLog will then display "CRS" which is the Magnetic Course:


Photo: ForeFlight example distance/heading check.
Click photo for a larger image

This works, but remember it isn't the True course, it is Magnetic. That should not be a problem since your FMS will most likely be using Magnetic as well.

ETPs and PSRs

You will need to enter at least one Equal Time Point (ETP), possibly a Point of Safe Return (PSR), and you may want to enter other points onto the chart that should not appear as routing waypoints.


Photo: ForeFlight, plotting an ETP, step 1
Click photo for a larger image

Press and hold a point on the route near the desired point. Select "More" on the location line and then "Save."


Photo: ForeFlight, plotting an ETP, step 2
Click photo for a larger image

From the next menu give the ETP a suitable name, correct the latitude and longitude. The default format probably isn't what you want: degrees.decimal degrees. To automatically enter degrees, minutes, and decimal minutes, use the format HDDDMMS, i.e., N53259 or W036406. (Latitude degrees must be in two digits, longitude degrees must be three digits.) However you enter it, it will be converted to degrees and decimal degrees.


Photo: ForeFlight, plotting an ETP, step 3
Click photo for a larger image

The resulting point is given within a triangle above a flag.

Navigation Accuracy Check

Photo: ForeFlight, Nav Accuracy Check
Click photo for a larger image

Using two fingers (using two hands makes this easier), simultaneously press the applicable VOR and the approximate aircraft position, fine tune the VOR position so it is exact, adjust the other until the radial and DME agree with your raw data, release both fingers. The resulting point should be right on the course line. This will not work, however, if you have been cleared direct off the projected course line. If you have a portable GPS linked to the iPad, you can work around this:


Photo: ForeFlight, Nav Accuracy Check, with a portable GPS unit
Click photo for a larger image

The blue orb is the aircraft position derived from the portable GPS unit. For more about how to use a portable GPS, see: Will a Portable GPS Unit Help?

Post Position Plot

Photo: ForeFlight, post-position plot
Click photo for a larger image

Post-position plots in ForeFlight are entered just as you would any other user non-routing point with a suitable name, as shown earlier with ETPs or PSRs.

JeppFD Example

Plotting your route

Photo: Copying the route
Click photo for a larger image

If you are using an interactive application to produce your plotting chart, you can cut and paste the route from either the application's master document or the PDF version of the master document. Press and hold any portion of the route until at least a portion of the route appears in inverse video. Then drag the start and end handles until the entire route is highlighted. Then select "Copy." You then go to the plotting application to the route entry appears, press and hold until you see a "paste" button.


Photo: Pasting the route into JeppFD
Click photo for a larger image


Photo: Pasting the route into JeppFD

You can paste the copied route into JeppFD by pulling down the Flight Plan bar, selecting "New," tapping the route window once, and then pressing and holding until the "paste" icon comes up.

Checking courses and distances

Photo: JeppFD, electronic plotter tool
Click photo for a larger image

The plotter icon in the tool bar shown on the right brings up an electronic plotter that you can position over a waypoint, resizing as necessary. With a steady hand, you should be able to get a course withing a few degrees accuracy. The distance, however, is hard to get within 20 nm.


Photo: JeppFD, distance work around technique
Click photo for a larger image

You can work around this by inserting a new route from one waypoint to the next. Be sure you save your flight plan first, as doing this will erase it from the display. Step by step: select the flight plan menu, save the flight plan, select "new flight" and type in the two waypoints in the route window. The distance appears on the top left of that window.

An even better solution will cost you $7.99 but is an app well worth having: FlyBy E6B. Simply select "Navigation" and then "Track and Distance" to get the following:


Photo: FlyByE6B, no deviation entered
Click photo for a larger image

Note that if you leave the "Var:" entry at zero, both numbers represent True courses and if you enter the magnetic variation both numbers are Magnetic courses:


Photo: FlyByE6B, with a deviation entered
Click photo for a larger image

The newest version of the program will enter the variation for you if you simply press the "Var:" button after you've entered the latitude and longitude.

ETPs and PSRs

Photo: JeppFD, Entering an ETP
Click photo for a larger image

To enter a non-routing point in JeppFD, press a point in the approximate position, enter a suitable name, and then fine-tune the latitude and longitude. Do not press "Add To Route" or "Direct To" but do press "Done."


Photo: JeppFD, ETP
Click photo for a larger image

Navigation Accuracy Check

Photo: JeppFD, Nav Accuracy Check
Click photo for a larger image

Make note of your aircraft's position by recording the latitude and longitude from the FMS while simultaneously making note of the VOR radial/DME. Create a user waypoint using these coordinates. Press the electronic plotter icon in JeppFD and move the plotter so it is precisely above the VOR. The user waypoint should be on the recorded radial and DME.

Post Position Plot

Photo: Two-degree check entered manually into JeppFD

Making a post-position plot using JeppFD with the iPad is quite easy. You derive the coordinates from your FMS and then press the course line in the approximate position. Then it is just a matter of correcting the approximate latitude and longitude with exact numbers and pressing "done."

Plotting with a Portable GPS

Will a portable GPS unit help? Most definitely.


Photo: The Dual XGPS at our cockpit window.
Click photo for a larger image

Some aircraft will broadcast your GPS position over a Wifi network and there are broadband providers, such as the Gogo system that will do the same. Now that might eliminate the need for a portable GPS receiver but I am not so sure. I prefer an independent solution since it is not tied to the aircraft and offers what I think is a better crosscheck. But there are others who think otherwise.

Is it legal? Yes, a portable GPS is allowed as just another PED. Commercial operators will need A061 OpSpec/MSpec/LOA approval, see: Personal Electronic Devices (PEDs). Some models can be linked to multiple iPads via a Bluetooth connection. These provide the best possible post-position plots and can be invaluable backups when things go wrong.

We have three. We normally use the Bad Elf GPS, available for about $200. (Amazon.) It seems to come up more quickly than the others and pairing to multiple iPads isn't a problem. Our backup is the Dual XGPS, which costs about $100. (Amazon. It doesn't seem to come up as quickly and every now and then it refuses to pair without rebooting the iPad. But it is cheap and having a backup seemed the prudent thing to do. We also carry a Garmin GDL 50 Portable ADS-B Receiver. It costs around $600. (Amazon) This offers us emergency navigation and attitude information in case we have greater problems than plotting.


Photo: Bad Elf App display
Click photo for a larger image

For the Bad Elf, as an example, Bluetooth pairing procedures are conventional. Simply turn the unit on, go to the Settings / Bluetooth menu on the iPad and pair. You may have to wait a few minutes for the unit to find the required number of satellites. Once that is done, you should see an airplane symbol on your charting applications.

The antenna is just below the LCD as you are facing it. We've heard from the company that if you open the App you can watch the signal strength change as you move it around the cockpit. Make sure you have it facing skyward and position it to maximize the signal strength on the App.


Photo: Example post-position plot using JeppFD and a portable GPS unit.
Click photo for a larger image

I've heard the argument that using a completely independent GPS violates the intent of AC 91-70B, ¶D.2.9.1, which says the plotting procedures should be made by using the "nonsteering LRNS." In my opinion this is nonsense. First, if your LRNS uses blended positions from GPS-updated IRUs, this is hardly an independent source. Second, how can you check the performance of one GPS using another GPS which uses much of the same hardware? I think using a portable GPS unit to display aircraft position on your iPad charting application is more accurate and offers an independent GPS source.

I believe you can simply check the GPS position on your iPad as an adequate position plot. Simply do a screen grab by pressing the "Home" and power buttons simultaneously to turn what you see into a photo. In the photo above, we plotted the position and waited a minute to allow the aircraft symbol to pass the plotted marker. Notice how both the plot and aircraft symbol are two miles right of course, because we had a 2 nm SLOP.

I think if you take care to ensure your cleared oceanic route is entered accurately into your plotting application, and if you diligently monitor the GPS symbol while doing screen grabs when plotting procedures call for them, you will not only be safer by ensuring you are on course, you will also be able to produce better position plots than manual methods will provide. You just need to make sure you carry out other oceanic record keeping duties, specifically with the Master Document. . . .

Even Better: A Portable ADS Receiver / GPS

You can buy perfectly good portable GPS units for less than $200 that will do a great job with plotting and we've done that. But you might also consider a portable ADS receiver with GPS. That will give you the same benefits plus a way of having a backup FMS and Attitude and Heading Reference System. That way if your cockpit avionics decide to take a vacation while you are halfway across the Atlantic, you will have a way of keeping the aircraft right-side-up as well as finding your divert airport.


Photo: On final approach, KBED RNAV Rwy 23, a view from ForeFlight using a Garmin GDL52 portable ADS receiver
Click photo for a six minute video of the approach

The video shown is using a Garmin GDL52, which cost us about $600. We paired it with our iPads and used ForeFlight to display the AHRS. You should get to know the system before you need it. The receiver unit needs to be placed on a fairly flat surface and generally facing forward. The resulting AHRS will be shown using ground speed, not indicated, and GPS altitude, not barometric. But that is a lot better than nothing!

An additional benefit is that if you don't have a moving map display capable of showing your aircraft position, the setup shown with ForeFlight will do that for you. And if you don't have ADS-B In, this unit gives you that capability to display air traffic ID, altitudes, and vectors.


Photo: Garmin GDL52, in cabin near a window
Click photo for a larger image

Master Document

Plotting procedures are designed to ensure you are on course. The traditional method with paper uses the master document as a check on your navigation method (usually a Flight Management Computer, FMC, or Flight Management System, an FMS). Even using an iPad and a portable GPS, the master document is still needed, as should be self evident with the procedures that follow.

How Do You Handle the Master Document?

The master document process depends on what applications you are using, but it is important to remember that you can only have one master document. If you are using ARINCDirect or another application that allows you to sync between iPads, you can have a single master document that will have each person's entries in different colors. If you do not have this capability, you can designate one pilot to control the master document as provided in an Adobe PDF format using Adobe Acrobat Reader or other application.

Depending on the application, typing involves selecting an "edit" icon or pen, selecting a color and/or font, selecting an area on the document, and typing using the provided keyboard. (You can also use a physical keyboard to the iPad using a Bluetooth connection.)


Photo: Typing on the iPad master document using Adobe Acrobat Reader

If you are transposing from a data link clearance, retyping onto the iPad is certainly neater and easier to read after the fact. If, on the other hand, you are recording from a clearance given over the radio, this could mean an extra step having to write the clearance on a notepad first.


Photo: iPad master document, front page, paper

You can also handwrite on the iPad using a stylus or even the tip of your finger. We find the typing option easier for most tasks. The "X" diagonals on each waypoint shown here were hand drawn.


Photo: iPad master document, oceanic page, paper

What About All Those Checklists?

You may have a number of checklists that require various entries for your oceanic flights. If so, you need only reproduce those in PDF form and then you can annotate them as shown for the master document. Here is an example from several years back:


Photo: Oceanic checklist and RVSM/Nav performance log example, iPad.

Our iPad version of this checklist is the same as the paper version and entries can be made by drawing, such as the check marks, or by typing. Here again the iPad version can be neater and offers better archival options. But once again it takes a little longer.

We have since weaved this checklist into our master document. So even in our quest to rid ourselves of paper, we managed to reduce the total number of documents too.

How Do You Archive (Record Keeping)?

You can easily save six months of records on your iPad but it would be better to save them someplace more secure and redundant. As with the other questions, the solution depends on your international trip planner or the applications you've invested in.

Depending on what you have, archiving can be easy:

  • ARINCDirect can archive everything for you into a "Documents" folder or, if combined with their FOS program, important documents can be saved remotely.
  • Even if you are working only with PDF files, a file transfer program like DropBox is an easy way to automatically duplicate your documents the next time you sync with the Internet.

Photo: Archive using DropBox.
Click photo for a larger image

  • You can also simply email anything you want saved to another person or another computer. Make sure you do a screen shot (by pressing the iPad HOME and POWER buttons simultaneously) of everything you want to make a record of. Then, after the flight, go to your Photos App, select each photo you want, and press the "Send" icon and select the email option.
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    Photo: Archive using screen shots.
    Click photo for a larger image

    Why the Pilot is the Last Line of Defense

    The following is extracted verbatim from Andreas Horn's exceptional pilot vlog Engineering Pilot.


    • In the early days of aviation, pilots used landmarks and light beacons to navigate. They were later replaced by radio beacons, such as NDB or VOR. The pilot or navigator would look up a beacon’s parameters on a map and then tune the specific frequency on the receiving equipment. He would then listen for the identification (a Morse code) and subsequently use the readout to determine the aircraft position. This paradigm imposed a heavy mental workload on the flight crew, but the “navigation data” (i.e. the maps) were quite primitive.
    • Today, the opposite is true: The creation of “navigation data” has become a complex undertaking and at the same time, the mental workload for the flight crew to find the way from Paris to Moscow is quite low, as pilots can simply enter the destination using a dedicated interface. There is just one problem: What if the waypoint in the aircraft database would be in a different location than the same waypoint on the map? This would obviously be a recipe for trouble and therefore it is vital that the integrity of our navigation data is ensured. But let us look in a step-by-step manner at how the aeronautical data is promulgated:
    • Traditionally, aeronautical data is distributed via a system of common effective dates, known as “Aeronautical Information Regulation And Control” (AIRAC). ICAO document 10066 specifies an aeronautical data catalogue, in order to facilitate the creation and distribution of digital data sets by the AIS of each member state. This also serves as an effort, to enable the transition from “paper AIP” as a reference to digital sources including meta data.
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      Photo: Data promulgation flow from state to aircraft, Horn, figure 3.
      Click photo for a larger image

    • In a simplified way, the flow can be described as in Figure 3 above. The states publish official data in their AIP. It is then “translated” into a code which is "machine readable", in this case: ARINC424. Then it is up the equipment manufacturer to format the data so that it can be stored on a particular memory of a product. Starting with the creation of "raw data" there are many steps involved and also multiple entities. So there are several occasions for the data to be corrupted.
    • It is obvious that the coordinates of a runway threshold as part of an RNP approach need to be strictly protected against corruption, while the radius of an en-route Fix-Radius-Transition (FRT) is less critical. ICAO Annex 15 stipulates three categories of data: Critical, essential and routine.
    • Andreas provides an example of critical data in an RNP approach which encodes several segments into values which are added up to produce a "Cyclic Redundancy Check (CRC)" value. The discussion is a bit technical and I encourage you to read his article in full if you are so inclined.

    • The CRC process was proposed in the 1960’s and has been adopted in many communication applications since. It is quite simple to implement in hardware, as it relies on polynomial division and modulo 2 arithmetic. The idea is brilliant: At the transmitter side, the data is divided by a so-called “generator polynomial”, which creates a remainder. (There are many rules as to how to choose the generator polynomial, but that would be beyond the scope of this article…). The CRC remainder is then “added” as a bit-sequence to the data. On the receiver side, the data string together with the CRC remainder are now divided by the same generator polynomial. This division will have no remainder, if all worked correctly. The reason for this is, that we are using binary division and modulo 2 arithmetic. Should there be a new remainder, the data would have been corrupted. A single changed bit will therefore be immediately detected.
    • There are significant drawbacks of CRC though, and it is being replaced more and more by Reed-Solomon codes and hash functions. The two major problems are that it does NOT protect against intentionally introduced errors and it’s capability to be used for error correction is quite limited. The former being increasingly relevant as aircraft data management is getting in the focus of cyber-security.
    • No matter what computer and algorithm we use, they all have one thing in common: The old programmer mantra: “GIGO” Garbage in – garbage out. So even the most sophisticated hash function will not prevent errors that are made right at the start of the process, during the data definition phase.
    • Therefore it is absolutely vital for every pilot to have a healthy level of skepticism towards the “green line” on the navigation display. A good practice can be to compare “desired tracks” and distances and to speak up and take action if something does not look right.

    Appendix: Software Mentioned

    While there are certainly other software packages out there that are as good or even better than the ones I've mentioned, here are the ones I've used on my journey going from paper to plastic.

    Adobe Acrobat Reader


    Photo: Adobe Acrobat Reader, from Apple App Store

    Available at: ARINCDirect

    The Adobe Acrobat Reader is free and provides a way of making notes, drawing lines, and adding check marks to your Master Document, plotting charts, and various checklists. The drawing tool is found by pressing the "pen" tool and then selecting "Comment." It simply draws a line where you drag your finger, isn't very precise, and doesn't offer special figures or ways to ensure the lines are straight. You might not need it if, like me, your other applications allow you to make annotations directly.



    Photo: ARINCDirect screen shot, from Eddie's iPad.

    Available at:

    The application itself is free if you have an ARINCDirect account. The price of that account varies depending on what you use them for. We use them for as much as we can, to include flight planning and aircraft phone service. I think we average between $300 and $500 a month. This program does everything well except plotting. They say they will have an upgrade that solves that deficiency. Until then, this application with JeppFD can be everything you need to go paperless when oceanic.

    The program operates seamlessly with their web-based application and their Flight Operations System (FOS) scheduling software. Depending on your airplane and subscription, the flight can be built automatically in FOS and sent to ARINCDirect and your aircraft FMS. You download the flight plan into your FMS and iPad. You then have a master document ready for annotations.



    Photo: DropBox screen shot, from Eddie's iPad.

    Available at:

    The application is free but there are additional charges for more storage space. You can simply email all your documents for a perfectly adequate way of archiving your oceanic paperwork, but DropBox makes this process easier. It is also a good way to have a full set of manuals on the iPad. (We get the same utility from ARINCDirect.)

    There are other file transfer utilities out there for the iPad that may have more features and might be easier to use. But I use DropBox for other things so it is easier for me to use it on the iPad too.



    Photo: ForeFlight screen shot, from Eddie's iPad.
    Click photo for a larger image

    Available at: ForeFlight

    This is a great tool for improving your situational awareness with terrain maps, synthetic vision, and weather flying domestically or oceanic. It is a pretty good oceanic plotter, however it has a strange quirk when it comes to measuring courses. (More about that below.)

    Garmin Pilot


    Photo: Garmin Pilot presentation (Courtesy Steven Foltz)
    Click photo for a larger image

    Available at: for $600 per year for the worldwide version.

    This is another great tool for improving your situational awareness with terrain maps, synthetic vision, and weather flying domestically or oceanic. It does one thing better than JeppFD and ARINCDirect when plotting: it gives you true course, magnetic course, and leg distances on one screen. If your flight planning provider gives you only a PFD master document without any interactive tools, Garmin Pilot could be the app for you.



    Photo: GoodReader screen shot, from Eddie's iPad.

    Available at: GoodReader.

    If you don't have an application that provides robust plotting and PDF comment tools, such as ARINCDirect and JeppFD, you will need a good PDF editing too. While the Adobe Acrobat Reader will do the job, it isn't very good at drawing lines. For that I recommend GoodReader.



    Photo: JeppFD plotting chart example
    Click photo for a larger image

    Available at:

    Price: hard to say. I've had Jeppesen worldwide accounts in the past that ran around $13,000 per year for worldwide coverage that gave you four installations. If you don't need worldwide coverage it would be less. Now I run a flight operation that needs four installations for the aircraft alone (the data exists in four places for redundancy) and we have four pilots on top of that. So that runs around $38,000 per year. The airplane can't fly without it so we don't have a lot of choice here.

    If you fly internationally as a non-military U.S. pilot, there is no substitute for Jeppesen charts. The only drawback with JeppFD is the course and distance measuring tools are crude. (More about that below.)

    Aeronautical Information Manual

    14 CFR 1, Title 14: Aeronautics and Space, Definitions and Abbreviations, Federal Aviation Administration, Department of Transportation

    14 CFR 91, Title 14: Aeronautics and Space, General Operating and Flight Rules, Federal Aviation Administration, Department of Transportation

    14 CFR 121, Title 14: Aeronautics and Space, Operating Requirements: Domestic, Flag, and Supplemental Operations, Federal Aviation Administration, Department of Transportation

    14 CFR 125, Title 14: Aeronautics and Space, Certification and Operations: Airplanes Having a Seating Capacity of 20 or More Passengers or a Maximum Payload Capacity of 6,000 Pounds or More; and Rules Governing Persons on Board Such Aircraft, Federal Aviation Administration, Department of Transportation

    14 CFR 135, Title 14: Aeronautics and Space, Operating Requirements: Commuter and On Demand Operations and Rules Governing Persons on Board Such Aircraft, Federal Aviation Administration, Department of Transportation

    47 CFR 22, Tile 47: Telecommunication, Federal Communications Commission

    A Report from the Portable Electronic Devices (PED) Aviation Rule Making Committee (ARC) to the Federal Aviation Administration (FAA), September 30, 2013

    Advisory Circular 91.21-1D, Use of Portable Electronic Devices Aboard Aircraft, 10/27/17, Department of Transportation

    *Advisory Circular 91-70A, Oceanic and International Operations, 8/12/10, U.S. Department of Transportation

    * This version of AC 91-70 has been superseded but it retained because it contains older guidance that helps place current guidance into perspective.

    Advisory Circular 91-70B, Oceanic and International Operations, 10/4/16, U.S. Department of Transportation

    Advisory Circular 120-76D, Authorization for use of Electronic Flight Bags, 10/27/17, Department of Transportation

    Aeronautical Information Manual

    Air Force Manual (AFM) 51-40, Air Navigation, Flying Training, 1 July 1973

    Horn, Andreas, "Getting to the right place," 9 October 2019, Engineering Pilot.

    FAA Orders 8400 and 8900

    ICAO Annex 4 - Aeronautical Charts, International Standards and Recommended Practices, Annex 4 to the Convention on International Civil Aviation, July 2009

    Information for Operators (InFO) 13010 Expanding Use of Passenger Portable Electronic Devices (PED), 10/31/13, U.S. Department of Transportation

    Information for Operators (InFO) Supplement 13010, FAA Aid to Operators for the Expanded Use of Passenger PEDs, June 9, 2014, Department of Transportation