the learning never stops!

Q & A

Academics

Over the years I've probably got several thousands of questions on the web and, I am afraid to say, I hardly ever make a record of them. I know this because sometimes when I am researching an answer, I realize that I once answered the question before. If only I had captured it the first time! Well let's see if we can fix that.


Most Recent Questions

Here are the most recent questions, this time around. I'll push these down below into alphabetic order the next time I update this page.

Airplane Flight Manual: Electronic or Paper?

Dear Eddie,

I have heard many stories on this issue but I am trying to clear the air on this topic. Are part 91 operators on the G550 with worldwide operations required to carry a paper copy of the Airplane Flight Manual onboard at all times or can an operator just use the electronic version (IPAD) by Gulfstream in the Planebook app?

Signed, R. Fader
Fort Lee, New Jersey

Mister Fader,

I was on stage at this year’s NBAA IOC sitting next to two FAA inspectors, one of those in charge of this very thing. I got a question about this and said the only thing you must have paper versions of is the aircraft registration, the certificate of airworthiness, your license, and your medical. I looked at the Fed and said, “have I got that right?” He said, “I think so.” We also shared the stage with a French SAFA inspector who wasn’t shy about chiming in, but he simply nodded his head.

That being said, in our G450 we don’t have electronic versions of all the ASCs, so we keep paper versions of those. But other than that, we are paperless.

Eddie

Nice C052 LOA, RNP(APCH) to fly into Nice, France

Dear Eddie,

I have a question regarding a new requirement at LFMN requiring RNP APCH specifications starting on March 1st, 2019. My operation has not received the C052 LOA yet and with this new requirement I'm not sure without it that I'm able/legal to do so. I've began the process of applying with the local FSDO but have an upcoming trip. You've touched on this topic to some extent and wondered what your thoughts are on the requirement at Nice and operations with/without C052.

Thanks for any insight you can provide.

Signed, R. Fader
Fort Lee, New Jersey

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Click photo for a larger image

Mister Fader,

If you are Part 91 I’m not sure you need C052 but you definitely need to make sure you have the RNAV A (GNSS) Rwy 04 and RNAV D (GNSS) Rwy 22 approaches available in your database and, to avoid a meeting after you land, be able to fly them if assigned. Ops.Group is reporting that aircraft are being stopped on the ramp and being asked for proof these approaches are loaded, and if not, they are filing violations.

C052 is available for Part 91 operators who need to prove to a foreign operator the authorization, but I haven’t heard France is asking for that. If you are a commercial operator get C052. If not, at least bring proof you’ve been trained. So that is my uneducated opinion. To get more educated, I contacted the good folks at temps-reel-nice-bf@aviation-civile.gouv.fr directly and here is what they said:

To answer your question, if the crew and the aircraft are able to fly the RNP (APCH) approaches specified in the AIC 33/18 [RNAV (GNSS) A, RNAV (GNSS) Y or Z and RNAV (GNSS) D], you don't need to get written authorization prior to fly to Nice."

Also note that the AIC that announned this (AIC 29/18) has been replaced by AIC 33/18. Make sure you are compliant with AIC 33/18 and make sure you have the correct approaches loaded in your FMS. I hope this works for you.

Eddie

RNP AR vs. Regular Old RNAV and/or RNP Approaches

Dear Eddie,

One more thing about RNP(GNSS), RNAV(RNP), and other such approaches that may or may not require special authorization. How can we tell the difference between one that does and one that does not require special authorization. Remember, back in the day, when they called them SAAAAAAAAR approaches? Life was so simple back then.

Signed, R. Fader
Fort Lee, New Jersey

Mister Fader,

I do remember those Special Aircraft and Aircrew Authorization Required (SAAAR) approaches and it was easier to identify them back then. They should be called RNAV(RNP) approaches these days, but standardization takes years for some of these things. Regardless, if special authorization is required, the approach is supposed to say so:

[ICAO Doc 9613, ¶6.2.5.1] The State AIP should clearly indicate that the navigation application is an RNP AR APCH procedure and that specific authorization is required. If distinct approvals are required for specific RNP AR APCH procedures or aerodromes, this requirement should be clearly identified by the State (see paragraph 6.3.2.2).

[ICAO Doc 9613, ¶6.3.2.2] Any operator with an appropriate operational approval may conduct RNP AR APCH instrument approach procedures, in a similar manner that operators with the proper authorization may conduct CAT II and CAT III ILS operations. This authorization may be in the form of a single approval for all RNP AR APCH procedures within a State, separate approvals for each RNP AR APCH procedure, or a combination of these methods (for example, State-wide approval for all procedures except those in highly challenging operational environments).

So here is how it should be done:

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Photo: Queenstown, New Zealand (NZQN) RNAV(RNP) Z Rwy 05, Jeppesen 12-20

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Notice the first note, "FOR OPERATORS WITH CAANZ RNP-AR APPROVAL ONLY." Here is another approach to the same airport without the note:

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Photo: Queenstown, New Zealand (NZQN) RNAV(GNSS) G Rwy, Jeppesen 12-2

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So that is how it is supposed to be done.

Eddie

Servicing Hydraulics on the Road (G450)

Dear Eddie,

I was on the road with my trusty G450 when the right hydraulic system synoptic showed us at 0.6 gallons, a bit low. Since it was so close to the "low" mark on the synoptic we decided to look at the actual mark on the reservoir piston after we landed. But there was nothing to see. We ended up flying home like that and got a "right hydraulic quantity low" CAS message just before landing. Our mechanics said we should have serviced it. But we were never taught how. Please teach us.

Signed, R. Fader
Fort Lee, New Jersey

Mister Fader,

As luck would have it, I was in the exact same situation a while back and I had never been trained either. We called in a local mechanic with GIV experience but he said the system was fine, since the digital readout in the aft equipment said the system was full. So he was no help. You may have noticed that the reservoir sits on its side and you may have heard that it takes "bootstrap" pressure to keep the reservoir properly pressurized. What that means to us pilots is that the engine has to be running to get a proper quantity indication. (Your mechanic can hook up an external source of pressure from a contraption known as a "mule" for some reason.) I took a few photos to communicate with our mechanic. Here is what we saw before we shut the engines down:

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Photo: G450 Right hydraulic system low synoptic, Eddie's aircraft

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So we shut the engines down and looked at the reservoir indicator:

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Photo: G450 Right hydraulic system reservoir piston, unpressurized, Eddie's aircraft

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I thought I could at least get a sense of the quantity but there is no indicator in sight. Turns out it was full scale to the right, since all that fluid was no longer pressurized. So next step was the digital readout:

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Photo: G450 aft equipment hydraulic reservoir indicator, left, Eddie's aircraft

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It is the same indicator you use when servicing engine oils, except you select "HYD" instead. Unlike the oils, you only see one side at a time and the system defaults to the left. You need to push the "SELECT" switch up once to get the right system:

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Photo: G450 aft equipment hydraulic reservoir indicator, right, Eddie's aircraft

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So, as you can see, it shows the right system at 0.95 gallons and "HI" which I assume means the quantity is registering at higher than that. But we know this is unpressurized. So I started the right engine and the quantity knocked down to 0.7 gallons, low but higher than what we saw in the cockpit. The reservoir piston showed us almost full:

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Photo: G450 Right hydraulic system reseroir piston, pressurized, Eddie's aircraft

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Our mechanic emailed us the applicable sections from the maintenance manual: (I am only showing the applicable portions)

[G450 MM, §12-15, ¶1.B3] Servicing reservoir with onboard replenisher

(3) Apply 3000 psi of hydraulic power to applicable system.

(4) Rotate selector valve (3) to applicable hydraulic system.

(5) On ground service panel (7) select GND SVC BUS SW (6) to ON.

(6) Hold replenisher pump switch (4) to ON until reservoir gage (2) indicates FULL. NOTE: Do not overfill reservoirs (Max capacity is 3.66 gallons, full is 2.75 gallons left system, 0.8 gallon right system).

(7) Rotate selector valve (3) to OFF.

(8) . . . (9)(c)

(9) (d) Repeat Step 1.B3.(3) thru Step 1.B3.(7) and service reservoir until cockpit indicator indicates FULL.

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Photo: G450 aft equipment hydraulic replenishing panel, Eddie's aircraft

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Our mechanic explained that the digital reservoir indicator in the aft equipment bay is not temperature compensated and that is why the manual requires you to judge using the cockpit indicator. So I had the other pilot in the cockpit running the engine and watching the synoptic. I selected "Right" from the reservoir handle, lifted the red guarded switch and added fluid until I saw 0.8 gallons. I ran to the cockpit and found the synoptic had only gone to 0.6 gallons. We agreed that I would go back and add fluid until the other pilot saw 0.8, at which point he would move the elevator back and forth. I would see the cables move (they are on the left side of the airplane) and stop the refill. And that is exactly what happened. The digital readout in aft equipment read 0.95 but the cockpit synoptic read 0.8 gallons. When you are done, make sure all the handles and switches are back to their original "off" and guarded positions.

The next flight, all was better:

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Photo: G450 hydraulics synoptic, the next flight, Eddie's aircraft

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If you want to do this, I recommend you have your mechanic give you some hands on training and then document the fact you had been trained.

Eddie

Note: this item has been added to: G450 Hydraulics System.


Past Questions and Answers

Approach Categories?

Is your approach category based on your actual or your maximum certificated landing weight. To me the answer was always obvious but there are many who read 14 CFR 97.3 a different way, all based on a single comma. I think we have more than a few pilots out there flying the wrong approach category. They will tell you that I don't know what I am talking about. In 2013 the FAA settled the matter but haven't changed the regulation to remove the confusion. Don't be confused, read on.

More about this: Approach Categories.

Dear Eddie,

I read that you claim my approach category is based on my maximum landing weight but that isn't what they taught me at Brand X Simulator company, where all the instructors are experts. They tell me that if we did that in our Challenger, we wouldn't be able to fly into Aspen and nobody believes that. Besides, isn't what we are worried about the actual maneuverability of the aircraft? So if I am 10,000 pounds below maximum landing weight, shouldn't I be allowed to fly the approach category that fits that speed? I've read Part 97.3 several times and I think the maximum landing weight only applies to aircraft that do not have a VREF, which ain't me.

Signed, R. Fader
Fort Lee, New Jersey

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Photo: Circling at Hilo, Hawaii

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Mister Fader,

I have been wrestling with this issue for many years, but in 2013 the FAA finally cleared it all up. The bottom line is this: you must use the maximum certificated landing weight, even if you have a VREF.

Eddie

[14 CFR 97.3] Aircraft approach category means a grouping of aircraft based on a speed of VREF, if specified, or if VREF is not specified, 1.3VSO at the maximum certificated weight. VSO, and the maximum certificated landing weight are those values as established for the aircraft by the certification authority of the country of registry.

These categories are as follows:

  • Category A: Speed less than 91 knots
  • Category B: Speed 91 knots or more but less than 121 knots
  • Category C: Speed 121 knots or more but less than 141 knots
  • Category D: Speed 141 knots or more but less than 166 knots
  • Category E: Speed 166 knots or more

There are some who would argue that maximum certificated weight only applies to 1.3VSO based on the placement of a comma in the regulation. The debate raged on for decades but the FAA finally provided some clarity in 2013:

[14 CFR 97.3 Interpretation]

  • This memorandum is in response to your request for legal interpretation on the meaning of "aircraft approach category" as defined 14 C.F.R. § 97.3 dated September 24, 2012. Specifically you ask if the phrase "maximum certificated landing weight" as used in § 97.3 applies to aircraft grouped by speed of VREF. The answer to your question is "yes" the phrase "maximum certificated landing weight" applies to both aircraft grouped by speed of VREF as well as aircraft grouped by 1.3 VSO.
  • In 1972 the FAA implemented the U.S. Standard for Terminal Instrument Procedures (TERPS). The TERPS rule changed the way the FAA defined aircraft approach categories from one based on the number of engines to new criteria based on stall speed in landing configuration or aircraft weight. Specifically "aircraft approach category" was defined as a "grouping of aircraft based on a speed of 1.3 VSO (at maximum certificated landing weight) or on maximum certificated landing weight." See 32 Fed. Reg. 13909,13911-12 (Oct 6, 1967); 32 Fed. Reg. 6938, 6939 (May 5, 1967). Section 97.3 was amended later to remove the option for basing aircraft approach categories strictly on maximum certificated landing weight. See 44 Fed. Reg. 15659 (Mar. 15, 1979). The only remaining way to make this determination was "1.3 VSO (at maximum certificated landing weight)." Id.
  • In 1996 the FAA proposed replacing "1.3 VSO" with "VREF" in the definition of "aircraft approach category" in § 97.3. See 61 Fed. Reg. 1260, 1263 (Jan. 18, 1996). The proposed definition specified that aircraft would be grouped "based on a speed of VREF at the maximum certificated landing weight." Id. at 1268. After additional review, the FAA determined that application of the VREF standard "to aircraft certificated using VS could cause confusion for users of the airspace system and that some airplane flight manuals would not be consistent with the new VREF terminology. See 67 Fed. Reg. 70812, 70822 (Nov. 26, 2002). Therefore, the FAA revised § 97.3 in the final rule to "continue to reference 1.3 VSO for use in those cases where VREF is not specified." Id.
  • The regulatory history demonstrates that the FAA intended the "maximum certificated landing weight" qualifier to apply to aircraft for which either VREF or 1.3 VSO are used to determine approach category. The new VREF standard as proposed in 1996 required "maximum certificated landing weight" to be part of the determination. The FAA revised the final rule so that aircraft approach categories could still be determined using the existing "1.3 VSO at maximum certificated landing weight" standard in addition to the VREF standard proposed in the NPRM. The preamble to the final rule contained no discussion of removing the reference to maximum certificated landing weight for the VREF standard proposed in the NPRM. We therefore conclude that for aircraft grouped by speed of VREF aircraft approach category must be determined using speed of VREF at the maximum certificated landing weight.

CAS Message Stack (Bottom of Top Priority Color First)

I've been hearing this since the first airplane I flew with a Crew Alerting System (CAS): Go to the bottom message of the highest priority CAS color, and there's your problem. I don't think it has ever been true, despite all the simulator instructors who have told you otherwise. This question has been added to: Immediate Action!

Dear Eddie,

I am in recurrent right now and our instructor said we should always look to the "bottom of the top" in our CAS message stack when deciding what checklist to run. If you have a stack of reds, ambers, and blues, look at the bottom red message. If you have a stack of ambers and blues, look to the bottom amber message. That way you will always find the cause of the problem. It worked in the simulator so maybe that's the way to go. Maybe you should add it to your rules of thumb.

Signed, R. Fader
Fort Lee, New Jersey

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Photo: Example message stack, from a G550

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Dear Mister Fader,

I can't answer for all airplanes but that rule of thumb doesn't work in many Gulfstreams. Look at the photo of a message stack from an electrical problem in a Gulfstream G550. The top stack is amber and the bottom of that stack says "Main DC Volts" above a long stack of blue CAS messages. If you go to the G550 QRH (page MB-43), you are told to reduce loads, end of checklist. So you have to complete the flight without the rest of that stuff in blue. But if you think the problem through and first attack the blue "L BPCU Fail" message, which tells you the Bus Power Control Unit has a problem. That checklist tells you to press the RESET button, and you get everything back.

So, Mister Fader, that would not be a good rule of thumb, at least not in a Gulfstream.

Eddie

Driftdown, "Really!"

This question has been added to: Oceanic Contingencies

Dear Eddie,

Your latest oceanic contingencies article got me to thinking more about the process. Essentially one is supposed to turn off the track and slow to drift down speed and continue in the same direction until descending below FL290 before making the turn back to your alternate.

I dug into the flight manual performance section regarding single engine procedures. Average numbers for our plane at weights and altitude near the single engine ETP point: 220 IAS, 380 TAS and a 300 fpm descent rate. Assuming no wind and starting from FL350, it would take about 22 minutes and 140 NM to get below 290. Then another 22 minutes not including the turn to get abeam the point at which the engine failed in the first place. Roughly 45 minutes spent before making headway to your landing. This seems counter intuitive and I was hoping for your insight.

Signed, R. Fader
Fort Lee, New Jersey

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Photo: Oceanic crossing tracks "Safe Zone" procedure

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Dear Mister Fader,

It is counterintuitive in many more ways than just the safety of your airplane. In the North Atlantic, especially, you have the safety of everyone around you to worry about. In the days before the skies became so crowded, the answer was to indeed drift down according to your aircraft’s best ability so as to milk every last forward mile possible. But these days, doing that could endanger other airplanes. Is it morally right to endanger an airliner filled with hundreds of people to improve the odds for the ten or so sitting behind your cockpit? But we do have greater communications and surveillance as well as TCAS to help out.

So, all that being said, here is my plan. I try to allow for enough fuel to keep a proper offset until above or below the tracks. If it happens, I’ll be communicating with the air traffic service unit and trying to get the best drift down I can, but I won’t do that unless I have clearance. This means you cannot be content with having just enough ETP fuel to make your destination. Here is some food for thought: The Great Escape.

Eddie

En Route Timing

This question has been added to: Oceanic Departure

Dear Eddie,

We were flying in Australian airspace the other day when center asked us to cross the next waypoint at a certain time. How do you do that? We couldn't find anything in the FMS to help us.

Signed, R. Fader
Fort Lee, New Jersey

Dear Mister Fader,

I've never used an FMS that does this automatically. You simply have to look at the ETA your FMS gives you and adjust your speed or your route until the ETA is correct. Of course this is easier said than done.

When speeding up your options are limited by the top speed your aircraft will do and this can be limited by your VMO, MMO, or other constraints such as turbulence or the airplane's RVSM limitations. This, of course, means there could be some math involved. I'll go through the math, but if you just want the procedures, look at the "Rules of Thumb" given.

Eddie

When en route, making pure, brute force changes to airspeed is usually the first option when adjusting.

Speed of sound = 573.8 nm/hour (above 36,000 feet)

M = TAS 573.8

Which means:

TAS = M * 573.8

It is helpful to know in advance how much speed you can gain by going as fast as you would normally want versus your normal cruise Mach, as well as how much you can lose my slowing as much as you would be comfortable doing at altitude. Say, for example, you normally cruise at M 0.80 and are willing to fly as fast as M 0.83.

TAS at M 0.80 = 0.80 * 573.8 = 459  nm/hr TAS at M 0.83 = 0.83 * 573.8 = 476  nm/hr

So that means we can cover the distance traveled in an hour at the original speed (459 nm/hr) more quickly:

time = distance velocity = 459 476 = 0.9643  hr

Multiplying by 60 converts that to minutes:

time = 0.9643  hours * 60  minutes/hour = 58  minutes

So speeding up by M 0.83 covers the same distance originally flown in 60 minutes in a time of 58 minutes. I'll leave the math up to you, but slowing down by M 0.03 will take 62 minutes.

You can do the same thing for other increments, if your aircraft allows it. Say, for example, you want to be able to speed up to M 0.85 or slow down to M 0.75. You will find that will gain or lose you 4 minutes.

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Timing: You can gain or lose two minutes by speeding up or slowing down by M 0.03

It is easier to lose time than gain it, obviously. To lose 2 minutes at lower altitudes you can make a standard rate 360 degree turn. At higher altitudes, you may have to settle for a half-standard rate because of bank angles, but that loses you 4 minutes.

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Photo: A 360° turn

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Timing: A standard rate 360 degree turn loses 2 minutes, a half-standard rate 360 degree turn loses 4 minutes.

For larger losses, a timing triangle can be used by flying 60 degrees off heading by the amount of time to be lost, then 60 degrees in the opposite direction, then 60 degrees back on course.

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Photo: A timing triangle

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Timing: A 60 degree turn off course for time t followed by a 60 degree turn back to course for time t and a 60 degree turn back on course will add time t to the en route ETE.


Fuel Quantity Update in the FMS?

This question has been added to: Trip Planning

Dear Eddie,

What’s the story behind the following Cruise checklist item in my Gulfstream: FMS Fuel Quantity....UPDATE?

I’ve heard that someone complained to GAC about consistently seeing a fuel quantity disparity between the FMS and the gauge so GAC simply added this item to the checklist. It’s there any truth to that or is that a myth??

Signed, R. Fader
Fort Lee, New Jersey

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Photo: G450 Fuel Quantity PERF INIT page

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Dear Mister Fader,

No that step is an important part of how you detect a fuel leak. The FMS performance computer is constantly monitoring how much fuel the engines should be burning to produce that number. You check it and reset it on level off and, I think, you should repeat that every hour. If there is a wide discrepancy, you should suspect a fuel leak.

Few Gulfstream pilots really understand how to do this. It becomes especially difficult when you take on large amounts of fuel. After you level off the fuel the FMS thinks you have could be several hundred pounds high or low depending on the starting temperature of the fuel and, therefore, its density. Who is right? They both are. The FMS gave you a more accurate idea of how much fuel was burned, the fuel gauge gives you a more accurate idea of how much fuel you have. It is important to understand both concepts. Now you want to reset the FMS so it again agrees with the gauge. Your SOP should tell you to repeat that process every hour. As the flight progresses, the disagreement should get smaller and smaller.

So how does this help with a fuel leak? Let’s say you develop a small fuel leak somewhere in the system, it really doesn’t matter where. But for some reason you are losing 1,000 lbs every hour. Let’s say this leak develops on hour 3 of an 8 hour oceanic crossing from White Plains to Rome. Chances are you will catch it since you make these checks against your master document. Now let’s say it happens on hour 3 of an 8 hour flight from Cape Town to Rome and you aren’t doing this master document hourly check. If you noticed the FMS was off by 300 lbs on level off (not unusual) and never checked it again you could be at risk. Now let’s say the leak starts right after level off and you are down 1,000 the first hour, 2,000 the second hour, and so on. By the time you might notice, it may be time to put the airplane down promptly in a location you would rather avoid. But if you checked at hour 2 and noticed you were down 1,000 lbs, you would be warned that something isn’t right.

Eddie

Landing Distance Available Confusion?

This question has been added to: Runway Data

Dear Eddie,

I tried to research this on my own with the help of your website and pulling down the general pub of Jeppesen pub but it went nowhere. Can you explain why the KSJC 10-9A lists displaced threshold distance (8463’) but note 5 states a LDA of 7614’? Our operation procedures has us insert the 8463’ in the HUD but it seems that may be erroneous. Any reference is kindly appreciated.

Signed, R. Fader
Fort Lee, New Jersey

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Photo: Extract, San Jose (KSJC) Jeppesen 10-9A page, 5 Oct 2018

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Dear Mister Fader,

The problem is not everything gets labeled on the airfield diagram. So at KSJC Runway 30L/12R you have an 11,000’ runway with some displaced threshold on both ends and what is unclear is how much of the opposite end displaced threshold is considered available as a stopway. The end result for us pilots is that the distances don’t always add up. San Jose isn’t alone in this. I’ve called various airport managers up about this and have been surprised that quite often they don’t know. I called airport operations at San Jose and they were very helpful.

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They sent the Airport Layout diagram. Everything adds up to within a foot now. The plan lists TODA = 11,000, ASDA = 10,152, LDA = 7,614, and Displaced Threshold = 2,537.

Doing the math, LDA = ADSA - DT = 10,152 - 2,537 = 7,615.

And, Landing Distance Beyond Threshold = TODA - DT = 11,000 - 2,537 = 8,463.

The difference between ASDA and TODA, in this case, is a stopway. It appears this runway has a 8463 - 7615 = 848’ stopway.

All of that brings us back to your original question: how much landing runway can you plan on? In this case, the shorter number is LDA which the ICAO says is “The length of runway which is declared available and suitable for the ground run of an aeroplane landing.” (Annex 14, Vol 1, Definitions) and the FAA says is “The runway length declared available and suitable for a landing airplane.” (AC 150/5300-13). This number does not include the stopway.

But what about the longer number? The landing distance beyond threshold does include the stopway. So what is a stopway? The ICAO says it is “A defined rectangular area on the ground at the end of take-off run available prepared as a suitable area in which an aircraft can be stopped in the case of an abandoned take off.” (Annex 14, Vol 1, Definitions) and the FAA says it is “An area designated by the airport beyond the takeoff runway able to support the aircraft during an aborted takeoff.” (14 CFR 1.1). So it is suitable or able, but not available. So it looks like the shorter number is the answer.

Eddie

Mysterious procedures from left field (EASA altimeter setting)?

This question has been added to: Altimeter Settings

Dear Eddie,

I was flying on a G650 recently and the pilot I was flying with did something interesting and I'm hoping you may enlighten me on, based on your knowledge/experience (I did review your code7700 page on altimeter procedures). Departing from Tokyo (TA=14,000 & TRL=FL140) we got cleared to FL190 when we were at around 4,000'. This pilot went ahead and selected 1013 on his altimeter. I have always waited until I was approaching the TA to set STD (29.92/1013). We discussed this at length but the bottom line is that he flies in Europe and he said the "standard" is now to set 1013 when you get cleared to a flight level; also that this is the "EASA standard" now. What say you?

Signed, R. Fader
Fort Lee, New Jersey

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Photo: QNE/QNH/QFE, from Altimeter Settings

Dear Mister Fader,

Unless something has changed since the last publication of EASA Air OPS, I don’t think that is right. AMC2 SPA.RVSM.105 says:

Emphasis should be placed on promptly setting the sub-scale on all primary and standby altimeters to 1013.2 hPa / 29.92 in Hg when passing the transition altitude, and rechecking for proper altimeter setting when reaching the initial cleared flight level."

I did a word search through the entire manual for “altimeter”, “transition altitude” , and “transition level” and did not come up with anything contrary to that. Besides, it sounds like a lousy technique. When climbing you always have the possibility of being asked to level off at a lower altitude below the transition altitude, and you will need the QNH to do that. On the other hand, if you are cleared below the transition level during descent I think it is a good technique to dial in the QNH so you don’t forget it. If you are given an intermediate level off above the transition level, one button press on most altimeters gets you back to QNE.

There is some debate about what the United Kingdom AIP has to say about this: "The vertical position of aircraft at, or below, any Transition Altitude will normally be expressed in terms of Altitude. The vertical position at, or above, any Transition Level will normally be expressed in terms of Flight Level. When descending through the Transition Layer the vertical position will be expressed by pilots in terms of Altitude, and when climbing in terms of Flight Level." Some pilots interpret "expressed" to mean "used." I called London Center and the controller asked around to be sure. They all agreed that you should not change from Altitude to Flight Level until you are reasonably assured you will be climbing above the Transition Level. Just like everyone else does it.

Whenever I hear something that surprises me I’ll say just that ("I did not know that!") and ask where I can find that in writing. I even did this when I was a young second lieutenant copilot in the Air Force where older (higher ranking officers) didn’t appreciate being questioned. “Gee sir, I didn’t know that! It looks like I need to get into the books! Where can I find that published so I can study some more?”

I hope that helps,

Eddie

On Course or Established?

Dear Eddie,

When can I consider myself “on course” or “established” for an approach? Everyone says just wait until the CDI is “off the wall” and you will be okay. I want to descend as soon as possible but how can I be sure I have obstacle clearance?

Signed, R. Fader
Fort Lee, New Jersey

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Photo: Proceeding Direct, from AFM 51-37.

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Mister Fader

I flew my first ILS looking at a course indicator and was told the same thing: I could consider myself on course when the CDI came "off the wall."

On a procedure turn, for example, it was okay to descend to the inbound altitude once the CDI was no longer fully deflected.

Years later I adopted a "centered or nothing" attitude, thinking I was better than a nearly fully deflected needle.

But it begs the question, do we have the required obstacle clearance when the needle just comes off the wall. If not, what about one dot?

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Photo: Localizer final trapezoid, from Eddie's notes.

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FAA Handbook 8083-15B, Instrument Flying Handbook, says one-quarter scale deflection means the airplane is aligned with the runway and full-scale deflection shows when the aircraft is 2.5° either side of centerline.

You cannot come up with a one size fits all rule about what full scale CDI deflection means. But doing the math, there are times when the needle comes off the wall a little early. I show that math on this website page: http://code7700.com/ils.htm#oncourse

So full scale is too much, waiting until the needles are centered can leave you too high for the procedure. But the FAA guidance is ambiguous. I think you should look at the ICAO Regs on this, ICAO Doc 8168, Procedures for Air Navigation Services, or PANSOPS, to be specific.

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Photo: ICAO "On Course," from ICAO Doc 8168.

Click photo for a larger image

That regulation says the tracking tolerance of the localizer/azimuth is much more narrow than for non-precision approaches and gives us the worst case scenario. In that scenario, “half scale deflection” keeps you in the protection area.

So in my opinion, that’s a good time to consider yourself on course or established: half scale deflection.

Eddie

Half of What Wind and All of What Gust?

More about this: Landing.

Eddie,

We all know we have to add half the wind and the full gust increment to our approach speeds. But do you add half the wind, or half the headwind?

Signed, R. Fader
Fort Lee, New Jersey

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Photo: Crosswinds, MROC, 21 Feb 2012, Bernal Saborio

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Mister Fader,

This has vexed me for a long time, but there is a more important question. But first, to answer your question. It depends on your manufacturer. Most simply state the wind itself, they don't want you doing the headwind component. Gulfstream, for example:

[G450 Airplane Flight Manual §5.11] If gusty wind conditions are present, add ½ of the steady state wind plus the full gust value to a maximum additive of 20 knots (VREF + 20). VREF will still be the target speed at the threshold.

Bombardier aircraft have a similar statement.

The other method is used by Boeing, in the 737NG, for example:

[Boeing 737 GN FCTM, p. 1.11] If the autothrottle is disconnected, or is planned to be disconnected prior to landing, the recommended method for approach speed correction is to add one half of the reported steady headwind component plus the full gust increment above the steady wind to the reference speed. The minimum command speed setting is VREF + 5 knots.

Dassault has a similar method and they have an even better explanation:

[F900EX CODDE2, ] Approach speed (VAPP) is the result of: VREF + wind correction. For wind correction (maximum 20 kt): apply half headwind + full gust increment. COMMENTS: The gust value should be taken into account whatever the wind direction is. For example for RWY 18, wind 120/20G30 given by the ATC: the steady state headwind component is 10 kt (crosswind component is 17 kt) and the full gust is 10 kt so the wind correction should be 15 kt (which is less than 20 kt).

So the technical answer depends on your aircraft manuals, but I think the right answer, the one that takes physics into consideration, has more to do with my bigger concern: stall speeds and stopping distance.

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Photo: Landing flare energy, from Eddie's notes.

Click photo for a larger image

Most aircraft use a VREF that is 1.3 times the stall speed, though some aircraft get as low as 1.23. You might think that 30 or 23 percent above stall speed is ample, but keep in mind the airplane has a downward vector which is aimed usually 3 degrees along the acceleration of gravity. You will need energy to stop that acceleration and that energy comes from your forward velocity. As you pull back on the yoke or stick, you are trading excess airspeed for a decreased downward vector.

Here's where it gets tricky. Your landing distance is more than likely based on touching down at VREF. Some manufacturers are explicit about this. Even though they want you to make the wind additive, they want you landing at VREF.

So let's say you do that. You are just a few feet off the ground at VREF and your negative gust hits. Now you have less energy to flare. Or lets say the positive gust hits. Now you are too fast for your landing data. What to do?

If I were writing the manual, I would recommend using half the headwind component plus all the gust, and then I would base my landing distance performance number on the highest possible touchdown speed. My AFM only provides for a 10 knot additive when computing landing distances and in a typical scenario that adds between 15 and 25 percent to my landing distance. If I know my required landing distance is more than 3/4 of the available runway, I know I will have to worry about the gust additive and perhaps find someplace else to land.

Eddie

Panel Cross Hairs?

Some questions seem silly but end up actually being useful. I wrote originally, "Why do you need to know this? You don't." But then someone pointed out that if you press gently on the crosshair you could reseat a broken connection. You (meaning me) are never to old to learn.

Dear Eddie,

I have been wondering about those little plus signs on my instrument panels, some people call them cross hairs. Why are they there. What are they for? Why do I, as a pilot, need to know about them?

Signed, R. Fader
Fort Lee, New Jersey

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Photo: Example panel, front

Click photo for a larger image

Dear Mister Fader,

I've seen these from various manufacturers, including Gulfstream. If you remove the panel and look on the back side, you will see an electrical connector. The cross hair appears to mark where that connection is, presumably for the lights of the panel. Why do you need to know this? If you lose panel lighting you might try gently pressing on the crosshair. It could reseat that connection.

Eddie

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Photo: Example panel, back

Click photo for a larger image

PANS OPS versus TERPS?

You know that when the approach plate says "PANS OPS" you aren't going to be flying a classic U.S. procedure turn the way you learned in the U.S. during instrument flight training. But sometimes when you are in a foreign country you see "TERPS" on the approach plate. Now what?

More about this: Course Reversals.

Dear Eddie,

My particular question is in regards to ICAO procedures. In general in the US we use FAA procedures and in non US areas use ICAO procedures. So at a field like Bagram in Afghanistan what procedures are actually in place when you fly a full procedure, ICAO or FAA? It seems unclear, most people I ask aren’t entirely sure and have flown in and out of there countless times which means clearly it isn’t that big a deal which isn't the best argument when flying expensive aircraft. So Bagram it would appear was TERPS'd by the US I would think yet it is a foreign country who has their own AIP but on the surface since FAA and ICAO use different TERPS criteria it would make sense to fly it based on who TERPS'd it. Either way it’s extremely confusing because there are good arguments to use FAA procedures and good arguments to use ICAO procedures so what is the correct answer?

Signed, R. Fader
Fort Lee, New Jersey

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Photo: Bagram, Afghanistan (OAIX) ILS or LOC DME Rwy 03R, Jeppesen 11-1, 15 Jun 18

Click photo for a larger image

Mister Fader,

You are quite right, it is confusing. When I was in the Air Force we taught that seeing "TERPS" on the approach plate meant you flew U.S. procedures, period. We believed there were two choices: TERPS and PANS OPS. But it is more complicated than that.

Bagram does indeed say TERPS on the chart and given that most of the traffic in and out of there is the U.S. military, I think flying a TERPS procedure entry would be a safe bet. In countries where the U.S. has a strong presence, the answer can be airport specific. Take a look at two airports in Germany, for example.

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Photo: Ramstein, Germany (ETAR) ILS or LOC Rwy 08, Jeppesen 11-1, 17 Nov 17

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Ramstein Air Base is a U.S. Air Force installation which primarily serves U.S. aircraft. The place on the chart we are used to seeing TERPS says "MIPS" which means "Military Instrument Procedures Standardization." MIPS is taken from a NATO supplement to ICAO Document 8168-OPS/611 Volume II. Confused? Well fly a little further east . . .

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Photo: Munich, Germany (EDDM) ILS or LOC Rwy 08L, Jeppesen 11-1, 26 Oct 18

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So in the same country you have two different approach types. The German AIP is silent on this subject which leads you to believe everything, everywhere is in accordance with PANS OPS and you will be entering the procedures in accordance with ICAO Doc 8168. But there is an agreement in place between Germany and the U.S. military that provides an exception. The only place we civilians can see that in writing is in the Jeppesen ATC pages for Germany, which state:

[Jeppesen Airways Manual, ATC, Europe, Germany] Instrument approach procedures for civil airports are based on the PANS-OPS, Document 8168. Instrument approach procedures for military aerodromes are based on the United States Standards for Terminal Procedures (TERPS) or based on Military Instrument Procedure Standardization (MIPS).

I imagine there is a similar agreement with Afghanistan but I haven't seen it anywhere. Jeppesen has this:

[Jeppesen Airways Manual, ATC, Middle East, Afghanistan] Instrument approach procedures are based on the United States Standards for Terminal Procedures (TERPS) and on the PANS-OPS, Document 8168.

The word "and" is a bit misleading: is it TERPS or PANS-OPS? Your approach says TERPS and I think that is a good assumption. I agree with you that it makes sense to fly U.S. TERPS procedures when flying an approach procedure that says that. But you have a leg up in that you seem to understand both. So if you are about to start a course reversal which is depicted as a procedure turn (or the other way around) and the TERPS answer is different than the PANS OPS answer, I would simply ask. “We are about to turn right to begin the procedure turn, does that check with your expectations?” The worst thing they can do to you is laugh and call you names. That is a small price to pay for clarity.

Plotting the Hawaii "Romeo" Routes?

More about this: Plotting 101

Dear Eddie,

Please settle a bet for us. We fly from California to Hawaii almost every other week and have all the Romeo Routes memorized. We all agree that we need to plot over the North Atlantic because those tracks change twice a day. But the Hawaii tracks have been set in stone as long as any of us can remember. So we think there is no need to plot when flying the fixed tracks between California and Hawaii. And that also means we don’t have to do the ten-minute post position plot either. That’s right, isn’t it?”

Signed, R. Fader
Fort Lee, New Jersey

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Photo: Plotting Required, from 8900.1, Vol 4, Ch 1, ¶4-80

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Mister Fader

No, that’s not right. Just because the route doesn't change on a daily basis doesn't mean you or your FMS will not make mistakes. The distance between ground-based navigation aids between California and Hawaii far exceeds those required by FAA Order 8900.1, Volume 4, Chapter 1, Paragraph 4-80.A, which says you must plot.

What the regulation says is that, “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.” If you are flying a turboprop, the distance decreases to 450 nautical miles.”

So what is the service volume on an ICAO standard ground-based navigational aid? Depending on your altitude, that can be anywhere from only 25 nautical miles for an NDB or up to 130 nautical miles for a VOR.

So, as a rule of thumb, I’ve always plotted if I was further than 800 nautical miles from the nearest usable VOR.

That same regulation, by the way, also specifies the 10-minute post position plot, so the same rule applies. You do need to do a post position plot.

Eddie

Visual Descent Points for "Impossible" Approaches

This question has been added to: Visual Descent Points

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Photo: KVNY VOR-B, Jeppesen KVNY 13-2, 4 Nov 16

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Dear Eddie,

The Van Nuys RWY 16R ILS is out of service for a while and we are now being issued the VOR-B when the weather is good, the VOR-A when it isn't. ATC will not approve a Circle Maneuver East of the airport because of KBUR ILS Rwy 8 Arrival flow / KBUR Rwy 15 Departure flow (Aircraft make climbing right turn towards KVNY). The airport is extremely difficult to find and especially so at night as you are not lined up with a runway and you are also not looking directly at the airport. I am flying a Challenger 605, which is Category D for Circling.

So for the VOR-B, the VDP is 3.2 NM and my target VS is 1,226 ft / min or call it 1,300 ft / min. Thus, if I do not see the runway before ZEXUG I am going to have to go missed and ask for the VOR-A or ILS RWY 8 KBUR VOR-B.

I am concerned about pilots wanting to make it work from the VOR-B and being even more encouraged to do so with the circling limitations. This combined with a shortened runway makes me feel like too fast, too steep, diving approach, with long landing on a now shortened runway will result in an over run accident soon.

Thanks.

Signed, R. Fader
Fort Lee, New Jersey

Dear Mister Fader,

You are right to be concerned, this looks like a bad situation at night or when the visibility goes down. First of all, as depicted, the approach cannot be flown on centerline with any hopes of being stable. When faced with such an approach, I like to draw out the "planned" descent rates. The person who drew the approach planned it just to get it done within the letter of any law that can be found in TERPS. Here is an example where "just because it is legal doesn't make it safe."

The only thing on this drawing you cannot get from the approach plate is the distance from the VOR to the touchdown zone (TDZ). I plotted that using GoogleEarth and got 0.6 nm.

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Photo: KVNY VOR-B, An unstable approach from minimums

Click photo for a larger image

As you can see from my drawing, You are much higher than a stable approach. This is what I call a "Flounder Approach." That comes from the movie "Animal House" where Bluto tells a pledge named Flounder, "Face it Flounder, you screwed up. You trusted us!"

To illustrate the math, I'll work out the first part of Option 1 for you right here. The altitude to lose is 3,580 - 2580 = 920 feet. The distance to lose that is 2.5 nm. So the required descent rate is (920 feet) / (2.5 nm) = 368 ft/nm. From your letter I gather you were doing the approach at 130 KTAS, so you will need a vertical velocity of (130 nm/hr) (368 ft/nm) (1 hr / 60 min) = 797 ft/min. Here is how it looks:

  • Option 1 (As published) PURSY to ZEXUG — 368 ft/nm (797 ft/min),
    then ZEXUG to TDZ — 574 ft/nm (1,244 ft/min)
  • That descent rate just 3 miles from touchdown is unsafe!

  • Option 2 Spot runway at PURSY, intercept 3° Glide Path at ZEXUG — 684 ft/nm 1,482 ft/nm)
    then 3° glide path — 318 ft/nm (689 ft/min)
  • Shoving the nose over for nearly 1,500 fpm at 5 nm might not be too bad, but it isn't good.)

  • Option 3 Spot runway at PURSY, fly to TDZ — 482 ft/nm (1,044 ft/nm)

In my opinion, if you haven't spotted the runway by PURSY, you should go around. If you do spot the runway at PURSY or sooner, you should maneuver east to pick up the ground track of the ILS and pick up a 3° glide path as soon as possible. You could even pick up a 3.5° glide path (as published for the ILS), the math is the same except that instead of descending at 318 ft/nm, you will be descending at 371 ft/nm.

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Photo: KVNY VOR-A, Jeppesen KVNY 13-1, 4 Nov 16

Click photo for a larger image

You mentioned the VOR-A as the low ceiling option. It could be that if you cannot spot the runway from that direction it is a nonstarter. But if you can, it may actually offer a better chance at a stable approach. The key point to remember is that you want to roll out on final 1.57 nm from the touchdown point to provide a stable approach at 500 feet AGL. Doing the math, you need to start down about a quarter of the way through the turn. I don't expect anyone to go through all this math, but you just need to envision that your target on rollout is 500' AGL.

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Photo: Circling KVNY from VOR-A to Runway 16R, the math

Click photo for a larger image

So if this was a day approach underneath a distinct ceiling with good visibility, the VOR-A could be a good option. But notice that the approach's viability minimum of 3 statute miles is only 2.6 nautical miles and I compute that you need to begin your turn at 2.75 nautical miles. I would be very tempted to bypass all this and head for Burbank.

References

14 CFR 97, Title 14: Aeronautics and Space, Standard Instrument Procedures, Federal Aviation Administration, Department of Transportation

14 CFR 97.3 Interpretation, AFS-400, 2013

Aeronautical Information Manual

Air Force Manual (AFM) 51-37, Instrument Flying, 1 December 1976

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

Boeing 737 NG Flight Crew Training Manual, Revision 12, June 30, 2013

Dassault Falcon 900X Crew Operational Documentation for Dassault non EASy (CODDE), Original, March 26, 2010.

FAA-H-8083-15, Instrument Flying Handbook, U.S. Department of Transportation, Flight Standards Service, 2001.

FAA Orders 8400 and 8900

Gulfstream G450 Airplane Flight Manual, Revision 35, April 18, 2013

Gulfstream G450 Maintenance Manual, Revision 18, Dec 12, 2013

ICAO Doc 8168 - Aircraft Operations - Vol I - Flight Procedures, Procedures for Air Navigation Services, International Civil Aviation Organization, 5th edition, 2006

ICAO Doc 9613 - Performance Based Navigation (PBN) Manual, International Civil Aviation Organization, 2008

United States Standard for Terminal Instrument Procedures (TERPS), Federal Aviation Administration 8260.3B CHG 25, 03/09/2012

Revision: 20190217
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