Why all the fuss about plotting procedures and checking Flight Management System programming over and over again when flying oceanic? If you download the FMS waypoints from the same people who filed the flight plan, what can go wrong? What indeed.
First, let's tackle the actual reason why. No matter where you fly, human error can creep into FMS programming (even when it is downloaded), flight plan transmission to ATC, and a failure of either of these things with any of the other aircraft you share the sky with. When you fly domestically, however, you normally have someone watching you on radar and in most parts of the world, a computer is watching for conflicts in real time. You don't have that when flying oceanic. So that's the why.
Second, let's talk about the likelihood of something going wrong when oceanic. You've been doing this for years and can't remember the last time you had a problem. Maybe you've never had a problem. But you've heard that general aviation has 10 percent of the traffic and 90 percent of the GNE's. That just isn't true. I've talked to oceanic controllers who say most of the problems come from military flights and from several third world countries. Of those that remain, the number of problems from the airlines and general aviation are about the same, despite the fact there are so many more airliners. The difference, I think, is that the system gets most of its funding from the airlines and they are willing to overlook their transgressions more easily.
We aren't here to point fingers, only to illustrate that GNEs do occur and that we need to be careful.
Everything here is from the references shown below, with a few comments in an alternate color.
[ICAO NAT Doc 007, ¶8.1.5] Regardless of how sophisticated or mature a system is, it is still essential that stringent navigation and cross checking procedures are maintained if Gross Navigation Errors (GNEs) are to be avoided. A GNE within NAT airspace is defined as a deviation from cleared track of 10 NM or more.
[ICAO NAT Doc 007, ¶8.1.6] All reported navigation errors in North Atlantic airspace are thoroughly investigated. Records show that navigation equipment or system technical failures are now fortunately rare. However, when they do occur they can sometimes be subtle or progressive, resulting in a gradual and perhaps not immediately discernible degradation of performance. Chapter 11 of this Manual provides guidance on detection and recovery when such problems are encountered.
[ICAO NAT Doc 007, ¶8.1.7] About half of NAT flights route via an OTS track and a large portion of the remaining random flights follow routes that at some point approach within one or two degrees of the outermost OTS tracks. One consequence of this is that a single digit error in the latitude of one significant point of an aircraft’s route definition will very likely lead to a conflict with another aircraft which is routing correctly via the resulting common significant point. The risk of an actual collision between two aircraft routing via a common point, as is the case when such errors are made, is further exacerbated by the improved technical accuracy of the modern navigation and height keeping equipment employed.
[ICAO NAT Doc 007, ¶8.1.8] The importance of employing strict navigation system operating procedures designed to avoid the insertion of wrong waypoints or misunderstandings between the flight crew and ATC over cleared routes cannot be over-emphasised.
[ICAO NAT Doc 007, ¶14.3.1] The most common causes of lateral navigation errors, in approximate order of frequency, have been as follows:
I was once flying from Anchorage, Alaska to Tokyo, Japan when our navigator made the classic east versus west error in our longitude. When the INS got to that waypoint the airplane made a sharp right turn. That was a good thing, it got all of our attentions. We were lucky it wasn't a more subtle error.
I was once asked to audit a company GNE where the crew simply downlinked the Europe to White Plains flight plan from satellite and saw 99 waypoints loaded but for some reason KHPN was missing from the last leg. They typed in KHPN and called it good. At 30°W the airplane cycled from the 99th waypoint, which was at 30°W, directly to KHPN. The crew wasn't plotting or even monitoring headings at each waypoint. I recommended the crew be required to face the consequences.
[ICAO NAT Doc 001, ¶5.5]
[ICAO NAT Doc 001, ¶5.10] Follow-up Action on Observed and Reported GNEs
In other words, they will be contacting the FAA. But what happens after that? I've asked and have never heard of certificate action as a result. The worst thing will be on behalf of the operator (or your owner). So, given that, what is the motivation? The answer is the obvious one: you don't want to hit anything or become lost.
[ICAO NAT Doc 007, ¶14.4] Perform navigation cross-check procedures throughout the ocean crossing. Do not relax or otherwise skip steps when it comes to following those procedures.
Cross-checks begin approaching each waypoint.
[ICAO NAT Doc 007, ¶14.4] Avoid casual R/T procedures. A number of GNEs have been the result of a misunderstanding between flight crew and controller as to the cleared route and/or flight level. Adhere strictly to proper R/T phraseology and do not be tempted to clip or abbreviate details of waypoint coordinates.
[ICAO NAT Doc 007, ¶14.4] Make an independent check on the gate position. Do not assume that the gate coordinates are correct without cross-checking with an authoritative source. Normally one expects coordinates to be to the nearest tenth of a minute. Therefore, ensure that the display is not to the hundredth, or in minutes and seconds. If the aircraft is near to the Zero Degree E/W (Greenwich) Meridian, remember the risk of confusing east and west.
Systems that use GPS for initialization are far less likely to have this problem. Make sure you follow your aircraft manufacturer's latest procedures. I once flew a Challenger 604 that allowed the initialization be updated at the end of the runway but the procedure discouraged this practice if GPS was installed. Some of our pilots would always update the initialization with runway position because that's what they did before GPS. They were, of course, decreasing the accuracy of the system.
[ICAO NAT Doc 007, ¶14.4] Before departure, at least two pilots should independently check that the following agree: computer flight plan, ICAO flight plan, track plotted on chart, and if appropriate, the track message. In flight, involve two different sources in the cross- checking, if possible. Do not be so hurried in loading waypoints that mistakes become likely, and always check waypoints against the current ATC clearance. Always be aware that the cleared route may differ from that contained in the filed flight plan. Prior to entering the NAT HLA ensure that the waypoints programmed into the navigation computer reflect the Oceanic Clearance received and not any different previously entered planned or requested route.
[ICAO NAT Doc 007, ¶14.4] Before entering Oceanic Airspace make a careful check of LRNS positions at or near to the last navigation facility – or perhaps the last but one.
There are many ways to do this, some more accurate than others.
[ICAO NAT Doc 007, ¶14.4] Do not initiate an on-track un-cleared level change. If a change of level is essential and prior ATC clearance cannot be obtained, treat this situation as a contingency and execute the appropriate contingency offset procedure, when possible before leaving the last cleared flight level. Inform ATC as soon as practicable.
This may seem almost nonsensical but it does happen.
[ICAO NAT Doc 007, ¶14.4] Do not assume that the aircraft is at a waypoint merely because the alert annunciator so indicates. Cross-check by reading present position.
[ICAO NAT Doc 007, ¶14.4] Complete navigation cross checks with more than one flight crew member. There are some tasks on the flight deck which can safely be delegated to one member of the flight crew, but navigation using automated systems is emphatically not one of them. All such cross-checks should be performed independently by at least two flight crew members.
[ICAO NAT Doc 007, ¶14.4] Complete flight progress charts periodically. Making periodic plots of position on a suitable chart and comparing with current cleared track, greatly helps in the identification of errors before getting too far from track.
Pilot message boards are filled with self-assured oceanic pilots claiming plotting is unnecessary. "I've been flying oceanic for thirty years," some of these will say, "and I've never plotted!" What you don't see are comments from all those sorry saps who got caught by personal error or just plain circumstance who could have been saved by a plotting chart. I've met several seasoned veterans who simply didn't know how and were afraid to admit that.
Copyright 2019. Code 7700 LLC. All Rights Reserved.