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19 September 2009

If charged, will Barkus argue that his GPS receiver was responsible?

If Greg Barkus is charged with a felony or misdemeanor for running his speedboat on the rocks, will he argue that a defective GPS receiver was responsible for the wreck?

That seems possible. Speaking in a conference call with Montana reporters earlier this month, Dennis Rehberg recalled that just before the crash, Barkus thought his GPS receiver was not reporting the boat’s correct position:

As they headed across the lake, the moon was up and half full, and Barkus was using a GPS unit to head east. He was standing up behind the wheel and talking to the group about how varied the depth was at different parts of Flathead Lake. Rehberg said Barkus was adjusting the GPS unit, because what he saw on the monitor wasn’t matching up with the terrain, and commented on how dark the night was along the east shore. Story by Dan Testa, Flathead Beacon.

They could not see the shoreline in the dark, Rehberg said, but at one point Barkus did seem confused by his GPS readings relative to their position on the lake. Barkus commented that the half-moon soon would be full, making night travel easier. Story by Michael Jamison, Missoulian.

Assuming that Rehberg’s recollections can be trusted — he’s surely telling what he believes is the truth, but he suffered some pretty serious injuries and his mind could be playing tricks on him — it’s possible the crash occurred because Barkus didn’t believe his instruments.

Now, it is possible, but I think highly improbable, that Barkus’ GPS receiver was providing a faulty readout because of an electrical problem, because waypoints had been entered incorrectly, or because the receiver’s basic settings, including the time offset from zero degrees longitude, had been entered incorrectly. Someone might even have tampered with the system.

Those are possibilities, and the investigating authorities will be examining them.

It is far more likely, I believe, that the GPS was correct, but that Barkus’ inner sense of his location was so strong that when confronted with evidence to the contrary, he rejected it, convinced that his instrument had to be wrong.

Trusting your senses instead of your compass is a fundamental navigational error that can be fatal. One classic example is Flight 19, the famous 1945 incident in which five U.S. Navy torpedo bombers vanished during a training flight east of Miami, Florida. This was, as pilot and author Larry Kusche proved in The Disappearance of Flight 19, his definitive account of the accident, almost certainly the result of the lead pilot’s becoming so disoriented in the hazy December afternoon that he refused to believe his compasses.

Another kind of spatial disorientation, one that may have been responsible for the fatal crash of John F. Kennedy Jr.’s Piper Saratoga, was described in 1993 by William Langewiesche in his classic article, The Turn.

Our species’ inclination to believe our senses instead of our instruments is so strong, and so potentially dangerous, that all navigation instructors constantly remind their students to believe their compass. That goes for GPS receivers, too.

Here’s what I want to know: if Barkus thought his GPS was reporting the wrong position, did he immediately stop until he verified his position by other means, such as compass sights on identifiable landmarks and navigation aids? Or did he simply tell his passengers that the GPS was in error, and continue his high speed run until its abrupt and bloody end?

Note. In an earlier post, before Rehberg told reporters that Barkus mentioned GPS difficulties, I opined that Barkus might have fallen asleep at the wheel. That’s still a possibility, and I won’t rule it out, but it now seems less probable than before.