Bits, Bytes & Weirdness

September 3, 2009 by Bruce Landsberg

High-tech-CockpitAs many of us gain exposure and flight hours with high tech flight decks, the more I am reminded of the need to still retain some of that “pilot stuff.”

An Airbus 319 recently lost all comm and transponder output in Europe due to a malfunction of the primary and backup electrical system. That’s supposed to be impossible in a Part 25 (air carrier) aircraft.

An ASRS Report on a Beechjet descending from the flight levels lost all airspeed indications, including back up. Perhaps this was what happened to the Air France Airbus in convective weather leaving Brazil. Total loss of airspeed indication – couldn’t happen – could it?

Closer to home, on return from Oshkosh, the database in my panel-mounted GPS got a little dyslexic. The plan was to go over Toledo, Ohio but the fuel computer advised that not only was I not going to have enough fuel for the trip but that the ETA was some 40 hours hence. The revelation came during cruise flight so there was plenty of time for head scratching.

Even more surprising was that TOL (the Toledo Vortac) had migrated some 4,000 miles to Southeast to somewhere in Brazil. Ahhhh, that would explain the mileage, time and fuel discrepancies. However, the TO NDB in Brazil had moved northwest to where Toledo had been in sort of a “sister cities” swap.

I loaded the TO identifier into the box and all the time, speed, distance and fuel parameters magically resolved themselves. It doesn’t take much imagination to see that in the terminal area this could be a major distraction.

Upon return, to query the database provider, Jeppesen pretty much said ” Well, why don’t you wait til the next update and if it doesn’t go away, call us back.” Interesting response for a flight safety critical piece of equipment.

Which brings me back to the blog title. Bits, Bytes and electrons can occasionally go haywire and we need to be sure that we always trust but verify. Single point failures are increasingly rare which means our ability to deal with them may need at least some occasional practice.

Anybody else had a similar experience?

Bruce Landsberg
Senior Safety Advisor, Air Safety Institute

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  • Nate

    I think Scotty said it best in one of the Star Trek movies: “The more turns they put in the plumbing, the easier it is to stop up the drain.”

    Caveat- I have zero time in glass panel or fly-by-wire aircraft. My remedy for airspeed indicator failure in the Skyhawk is to set a power setting taught by my instructor and keep the horizon halfway up the windscreen. Its worked so far….

  • Alberto Silva

    Response to the issue of the database provided asking to wait until the next update to see if the problem goes away: I thought that my experience at this was limited to the database in my Lowrance 1000. Then I found that the problem extends to all databases, including the G-1000 and nobody is interested in fixing the problem. I have written to Lowrance and Jeppensen to no avail. It is a small problem without any consequences for me because the misrepresentation happens to be close to my home airport. The issue is in the area just west of the Kennedy Space Center. If you look at the Orlando TAC, you see that the class D airspace of the Shuttle Landing Facility truncated by restricted area 2934. This leaves the Indian River corridor outside of TTS class D airspace. In every single base map that I have seen, including all of the ones I could check at Sun’n Fun, This class D airspace encroaches into the river. It is just wrong, I have shown it to numerous representatives, written about it to the companies, and it has not been fixed in years. It may not be a big deal because the consequence is that pilots who don’t look at the chart will make an extra call to TTS where they are probably told that the call is not necessary. However, the mistake should be corrected. Moral of the story is that I think thath all these details are important and, regardless of your equipment level, make sure that you crosscheck critical data along the route of flight.

  • Cary Alburn

    I have no experience with glass cockpits, but back when I was instructing more than 25 years ago, a similar issue was when students would fixate on the gauges instead of looking outside. More recently I encountered a similar issue: a low-time private pilot who mistakenly landed in the dark at Fort Collins Downtown (just a couple months before it was closed 2 years ago), thinking he was in Cheyenne! (the difference between a multi-runway airport where the east-west runway is 9200′ x 150′ and a single runway airport of 4800′ x 50′ wasn’t obvious to him). He and his wife had come from Jackson, WY, and along the way his handheld GPS had failed–and he couldn’t remember how to navigate with the VORs in the airplane! When I looked in his tanks, there was no visible fuel–yet he was wanting to take off and fly to Fort Collins Loveland, some 7 miles on south to refuel.

    The trouble with all of the current doodads is that basic flying skills seem to be taking a back seat. Pilots can’t fly without doodads; they can’t navigate without doodads. The other day I was privileged to fly in a 1948 C140–it has a single navcom and transponder, but that’s it–no fancy gyros even. If more people learned how to fly in such basic airplanes, some of the rather idiotic issues that you’ve described, Bruce, might not happen. Or as my primary instructor used to say back in 1972: Fly the airplane first–all else is second.


  • Jim McSherry

    Database errors are not the only gremlins waiting to overcome logic with blind electronic faith. On a recent flight with a Cirrus factory instructor, we observed a “discrepancy” when the MFD indicated that we had 2 gal of fuel remaining, when my watch and the analog gauges indicated that we should have around 16-18 gal. The factory guy (half my age, but that’s no matter) insisted we return to the most recent airport, where we learned that we now had about 12 gal for our half-hour flight to home base. I bought a few more for insurance, but without the return it would have been superfluous.
    I had more faith in the time or the float gauges – he had more faith in the computer; we later gleaned that in going through the ‘failure modes’ on the MFD, it had likely erased the memory of the prior flight time, and based its fuel data on the most recent takeoff & climb, resulting in a huge fuel flow rate, and a wrong conclusion…Hmmm, remember “garbage in, garbage out”?
    I, too, learned in a Cherokee with a VOR, all the way thru instrument; learned to build the picture in my head. Now I frequently dim the screen on the GPS for much of the training flight, just to let the client get the same opportunity. Flying with “doodads” is fine, as long as we remember who is boss. Eyes outside, and fly the airplane!

    Fly safe,

  • Lance De Foa

    I think it is time for profit motivated aviation database vendors let safety motivated open-source pilots (and their associations) become the custodians of aviation navigation data, like a wikipedia of nav data. (It is too bad that the DAFIF is no longer freely available – I suspect it was private financial concerns rather than security or liability reasons that brought that about).

    The vendors of VFR GPS units should open their databases so that pilots can add their favourite private strip, with the same data that a registered airport has. I suspect that many VFR pilots rarely update their databases so potential lost revenue is likely small, while the potential safety gains from freely available data updates is invaluable (anyone who knows how to copy a file to an SD card should be able to do it).

    Are there any hacker pilots who would be willing to help unlock the database formats?


  • George M. Powell

    The GPS Array can be all shut down by lasers. Pilots should still be capable of navigating using ground based devices – ie, VORs and approaches using ILS. Rendering the GPS Satellites inoperative in conjunction with other attacks will have disastrous consequenses. The USA does have enemies !