Error of Your Ways

You probably wont spot a mistake on your charts, but then again …


Some 14 months ago, 20 people died when a U.S. Marines Prowler cut a ski gondola cable in a valley near Cavalese, Italy. Captain Richard Ashby, the pilot, and Captain Joseph Schwitzer, the navigator, were facing trial on criminal charges as this issue went to press. Although the easy explanation is that the jet was flying too fast and too low through the valley, the scenario includes another twist.

Air crews rely on maps given to them by the United States to plan their mission, says Frank Spinner, a civilian lawyer hired to assist Ashbys military lawyers. When you have an uncharted obstruction that goes 500 feet above ground level smack in the middle of an approved low-altitude route, how could you expect them to know that it exists?

The CBS program 60 Minutes aired a segment in January entitled Mishap Valley in which it displayed a copy of the navigation chart the crew had used, and alleged that the gondola was not depicted. The crew claims they would never have flown that low in the valley if they had known there was an obstacle.

Although the chart applicable to the accident was for VFR use and the situation goes far beyond the accuracy of the charts, it begs an important question: can you really rely on the charts you buy?

The amount of information chart publishers must compile to present accurate charts is staggering. Airways, intersections, navaids, airspace, Military Operating Areas, prohibited airspace, topography, and airport location and information all come from different sources.

With about 10,000 airport and navaid changes alone each year, the sheer volume of information means that the people processing the changes will, from time to time, make a mistake. And, although they are kept to an amazing minimum, errors and inconsistencies on enroute charts and instrument approach plates can occur.

You may use some incorrect charts without even knowing it owing to the fact that you actually use only a small fraction of the information on an enroute chart. Other errors are corrected by Notam, and ATC instructions can render the mistake moot.

Occasionally, however, one squeaks in. For example, a pilot flying a practice NDB approach in Leesburg, Fla., noticed that the NDB 31 approach has a minimum descent altitude of 900 feet. However, the missed approach instructions on the NOS chart said to climb to 800 and to proceed to a named waypoint as a holding fix. The holding fix was not depicted on the chart.

The explanation for this may be that someone in the production department copied the missed approach instructions the GPS approach, which has lower minimums and includes the named waypoint. The error on the chart was published for at least four cycles during late 1998 and was finally corrected in the January 28, 1999, cycle.

How could this happen? The simple explanation is human error. Why the mistake hung on so long is not so easy. Although the traffic at Leesburg is generally light and the weather is rarely at minimums, it is used by a nearby flight academy for NDB practice. Under those circumstances, its likely that more than one instructor noted the error and gave the real missed approach instructions to their students, but no one bothered reporting the error to the NOS.

Interestingly enough, the Jeppesen charts never published the error. This may be because the editing procedures at Jeppesen include a second step. First, as is done at NOAA, people edit the charts. Then Jeppesen goes a step further and applies sophisticated in-house software that runs through the procedure and checks for inconsistencies. This process is the probable reason that the error on the Leesburg NDB 31 approach plate that was on the NOS chart for four cycles was never published on the Jeppesen plate.

Software aside, Jeppesen, like NOAA, must rely heavily on the accuracy of the information it receives from official government agencies. For a feel of how confident Jeppesen is of the government data, look no farther than the Warranty and Copyright it supplies with its products. The company essentially disavows any responsibility of the accuracy of the information, saying its charts simply depict in a graphic form convenient for the use of knowledgeable, instrument-rated pilots, the flight procedures exactly as designed, flight-tested and prescribed by government authorities.

Blunders on the Fly
The potential for a botched chart, however small, add ammunition to the notion that you should brief your intended procedures well in advance. Descending through the soup is the wrong time to discover that the missed approach instructions are nonsensical.

If you find errors in the charts, your next course of action depends largely on the situation. If youre in the air, advise ATC of the error so they can alert pilots using the procedure of the situation until an FDC Notam is issued or a correct chart is published. Controllers can also make recommendations for the safe continuation of the flight. For example, if an incorrect frequency is published the controller likely knows the correct information. This is also true if a decision height is wrong or other simple errors crop up.

If you encounter an error on an instrument approach, it may be advisable to fly a different approach, if one is available, depending on the magnitude of the error.

Once on the ground, make it your responsibility to bring the error to the attention of the publisher of the chart. There are multiple ways to do this. For charts published by NOAA, you can find contact information on the inside cover of the IAP book or the cover of the enroute chart. You can call, write or send e-mail. If you call the toll-free number, you will be instructed to leave a message, and a staff cartographer will return your call. Input from the public is sent to the appropriate division or section to be addressed. After the AC&C verifies data sent by the public, it is forwarded to the FAA. Notams are then issued, when appropriate, to inform the public of the change. In 1998, AC&C received more than 330 e-mails, 700 calls and 70 letters. Jeppesen includes comment cards in the front section of the first binder or can be contacted by telephone.

Spreading the Word
There are three basic kinds of Notams – distant, local and FDC.

Distant Notams, or Notam(D), are circulated to all air traffic facilities and FSS until they are published. These Notams will address navigational facilities, public-use airports, seaports and heliports. Local Notams, or Notam(L), are distributed locally and include such information as taxiway closures, airport grounds work, and outages of items that do not affect approach capability, including rotating beacons and VASI lights. FDC Notams include amendments to charts and temporary flight restrictions.

If the Notam is urgent, which is extremely rare, the NOAA or Jeppesen will contact the controlling agency (appropriate air traffic control) directly and notify them. Most often errors come in the form of new information that was not put on the chart because the source simply missed the publishing deadline.

The vast majority of errors on charts can be discovered prior to flight by doing a thorough check of the Terminal Change Notice (NOS), Chart and Enroute Notams (Jeppesen) and FDC Notams.

The NOS Terminal Change Notice is a publication of which most pilots are unaware. The Terminal Change Notice is available by subscription, and is published and distributed mid-cycle. For example, the Terminal Procedures that were effective February 26, 1998, through April 23, 1998, required consultation of the Change Notice that became effective March 26, 1998, to be considered current. Change Notices contain an average of 80 updated terminal procedures, including approaches, departure procedures and STARS.

Jeppesens Chart and Enroute Notams are published every other week. This information is sent to subscribers and is available for download on the Jeppesen web site. They generally include two types of information: data that missed the publication date and temporary information such as a crane in the approach path.

There are basically two ways to check FDC Notams – dial up DUAT or call a Flight Service Station. Although the computer may seem more convenient to those who are tied into the digital world, the FSS route may be a surer method of covering your bases.

Information Overload
The AOPA recommends having a Flight Service Specialist review the Notams and relay the information to you. This has several advantages over DUAT. Not only is a Flight Service Specialist trained to decode the Notams and relay accurate information, the conversation is recorded and is evidence that the pilot received them. Although DUATS will record that a pilot receives the information, there is no proof that it has been read. A recorded conversation of a pilot receiving the Notams during a pre-flight briefing from FSS is more convincing evidence if legal action were ever to occur. A Flight Service Specialist can quickly relay the pertinent Notams, which will not only save a pilot time, but puts the burden of a missed Notam back on the FSS.

It is also important to note that it may be necessary to ask the Flight Service Specialist for FDC and local Notams. Do not assume that you will receive this information during your briefing. If you do not receive any FDC or local Notams during a briefing, confirm that this was because there were none, not that they were simply overlooked.

In the final analysis, both NOAA and Jeppesen go to great lengths to put out quality publications. Consider the barrage of information that comes in and marvel at the fact that each organization consistently produces charts that are virtually error-free.

An accurate chart is only helpful if you have one, so make sure that your charts are up to date. And just like you do with a clearance, acknowledge the information and then apply skepticism. It is worthwhile to study the charts before departure, instead of arriving at the initial approach fix only to discover an inconsistency. This is not only a good way to head off chart errors; it is a professional way to approach instrument flying.

Reviewing the Enroute Charts and Terminal Procedures should become part of your preflight planning routine. It affords you the opportunity to confirm that you have the correct, up-to-date charts on board and within reach. (Are you sure the line person who vacuumed the interior put them back where you had them?)

Reading the charts on the ground alleviates the pressure of reading them for the first time in turbulence, when the electrical system just went out and you only have a flashlight, or any other inconvenient situation you may run across while in the air. Having read the charts on the ground takes away a little piece of unnecessary stress, eliminating one link in the error chain that is always lurking somewhere in the background.

Also With This Article
Click here to view “Choreographing the Dance of Data.”
Click here to view “DOT or FAA May Inherit the Chore of Building Charts.”
Click here to view “One That Slipped Through the Cracks.”

-by Kimberly Sailor

Kimberly Sailor is a corporate pilot and CFII who also serves as the president of the Windy City Chapter of Women in Aviation International.


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