I'm not a pilot, but on a clear day I can pretty much figure out where we are by looking out the side window. Having flown HSV-DTW many many times I know what Nashville, Louisville, Cincinnati, the Ohio river, Toledo and other landmarks look like. If you can see freeways and have a map you could navigate. I don't see GPS receivers as any kind of threat.

But the 9/11 culprits were not familiar, were not American, were not used to identifying the same landmarks from years of flying the same airline out of the same airports. To someone like that, one freeway looks like another, one river looks like another, and Nashville, Louisville and Cincy would all look the same, more or less, medium large cities on a big river.

And just picture the view out your side window on a hazy, humid day with 7 to 10 mile visibility, broken cumulus clouds etc. Was America just unlucky on the morning of 9/11/01 that there were no clouds, visibility unlimited? Some of you may recall that the evening of 9/10/01 was quite stormy over the Northeast corridor with numerous thunderstorms.

Whether or not GPS receivers aided the 9/11 terrorists in carrying out their flights to destruction, we cannot know. AA 11 could have followed the Hudson River, but both AA 77 (the Pentagon plane) and UA 93 both flew more or less straight lines towards DC. But given the fact that the TSA fears onboard nail files and corkscrews, I remain surprised that they have never been concerned about a device that could potentially allow hijackers to fly directly to a pre-programmed target.

Keep in mind, I am not personally advocating the ban of GPS receivers or their use aboard airliners. I think the root solution to 9/11 was better screening, hardened cockpit doors and wholesale revision in the "rules of engagement" with hijackers.

If GPS's were to be banned, I would think that all electronic devices would have to be banned for carryon use. GPS devices are built into cell phones, watches, PDAs and mixed in with all of the stuff that can attach to a laptop. I just can't see the nice TSA people examining every device to see if there is a GPS included with it.

"I am sorry sir, but this Braun shaver could have a GPS in it" Into the confiscation bin it goes.

True enough, although I do not know how well those devices would function in an airplane. But assuming they could be made to work in a plane, that would present a real problem to the TSA.

The TSA can't even find obvious test bombs in luggage - I hardly think they could figure out which electronic device is capable of doing which function.

The person using the cabin intercom could very well not be trained in any aspect of operating a plane. Besides, broadcasting that communication wouldn't have made a difference anyone. Pre-Sept 11, no one would even think of scrambling fighter jets to take out a passenger jet.

There is no information avaliable (to us, at least) that proves that the pilots were incapacitated before they brought the plane to their final destinations. They could very welll be attacked after they were just about done with it.
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Read the report:

http://www.9-11commission.gov/report/911Report_Ch1.htm

There were numerous phone calls made from the plane by passengers and FAs which led to the conclusion that the pilots were NOT in the cockpit. Also, the unauthorized altitude excursions of all of the hijacked aircraft which followed the time of the suspected takeovers would also lead to the conclusion that the pilots were no longer at the controls. Also, keep in mind that the CVR from UA 93 was recovered. They know exactly what was said in that cockpit word for word.

Still the greater point is not whether the 9/11 hijackers could have navigated without GPS assistence. Sure, it is possible. But I suspect that they might have used portable GPS devices that were pre-programmed with their targets.

But as has been pointed out recently, GPS capability is integrated into so many devices now that it would be impossible to stop without banning all electronic devices from the cabin altogether! The Brits kind of tried that for a few days last summer, but the airlines did not like checking laptops for a moment!

They could have used them, but maybe the didn't. I don't see a reason to ban GPS onboard an aircraft.

I don't think precise location data is necessary to guide an airliner to Washington or New York. Even a primitive knowledge of dead-reckoning navigation would have got them close enough to pick up adequate visual references to complete the mission by pilotage. Would a consumer-grade circa 2001 GPS even be capable of acquiring a useful fix in an airliner?

But the fundamental reality is that anyone who ever tries to hijack an airliner will be killed by the passengers.

I tried to use my Nuvi 660 on a flight. Only for a very short period did it pick up a signal and only when held literally against the window. Still was cool to see a speed ot 10 billion (or so) MPH.