There are many threads over the years regarding in flight GPS units, which airlines allow and which do not, whether they can be used below 10,000 feet etc. I would like to discuss simply the concept of in flight security as relates to GPS units.

After the events of 9/11/01, I have always been somewhat amazed that many carriers continued to allow the use of GPS units in flight. There is certainly a high tactical value in allowing someone who intends evil to know their exact location. And even more so to a device that can be pre-programmed to track to any precise location from the current position.

This may sound like a nervous old lady, but I have even wondered whether the ever-present moving maps that are aboard so many aircraft provide too much information to those that have evil intents!

being able to look out and SEE where you are - oh the horror.

More seriously, exactly what risk do you see here? With a watch and a very basic knowledge of airspeed/course you could figure out almost exactly where a commercial flight is anyway, and in addition even if you know the location down to +/- 1 meter, so what?

And if you take over the cockpit, I think we can all assume that commercial airliners have some sort of tools which allow the pilots to know where they are.

Unless you're positing a scenario where blowing up the plane at some VERY precise spot is critical, I just don't see a problem here. What are you worried about?

Bob

If you go back to the events of 9/11, one of the factors that I have never thought received much attention is how the hijackers managed to take over the cockpits of the two BOS-LAX flights somewhere over southern VT or upstate NY and manage to find the WTC towers. Or the AA flight that managed turn around and find the Pentagon.

These were not professional pilots who knew how to use the aircraft complex navigation systems. The weather that morning was severe clear and the hijackers may have been able to see landmarks for 50 miles. As an experienced pilot, I can pick out landmarks easily. But infrequent pilots/amateurs can easily get lost even on a severe clear day. And suppose the day was 10 miles visibility in haze... a nice day on the ground, but how would they have found their targets on that kind of day? What if there had been a broken cloud deck?

I would not be surprised at all if the 9/11 hijackers relied on portable GPS receivers to guide them to their targets. To argue that they did this by sight alone, simply by visual reference, strains credulity.

Now as far as I am concerned, the issue was solved by establishing better cockpit security procedures and hardened cockpit doors. But given the fact that the TSA has taken my wine corkscrews and nail clippers in the past, I am surprised that the use of GPS receivers has not attracted more concern.

Might as well get rid of FlightAware.com while you're at it. heaven forbid people know where they are instead of asking the FA "Are we there yet?" "How much longer?"

I thought about trying my Nuvi 670 on an AF flight that I just returned from Yesterday.

But what I found was that it was having difficulties getting a signal inside a hotel room.

Besides, AF has an onboard navigation system which shows all the nearby cities as well as a pretty good topographical representation of where you're flying over at a given point.

So I didn't see the point.

I disagree. All they had to do was tune to a VOR in DC, or just use the aircraft computer to figure out which way to point the plane. The hijacker pilots had flight training in commercial aircraft and would have known how to do this. One in the vicinity of the target city, the desired target would have been easy to find.

First, the hijackers had training in Cessna 172s, not commercial aircraft. I guarantee you that one cannot simply use the aircraft computer or even its GPS systems without a whole lot of training. There are complex menus within menus to use these systrems. And once "in the vicinity", the targets might have been easy to find if you had unlimited visibility conditions (which the happened to have had that day). But what if the visibility had only been 10 miles... a good day to those on the ground, but not a good day for visually finding anything.

Check out the radar tracks about 2/3rds the way through this report:

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

AA 77 and UA 93 knew precisely where they were headed. It certainly would have been easy for the investigators to figure out whether they were on a VOR radial or not. UA93 turns around over Cleveland... certainly too far to receive any of the DC VOR signals, yet its course does not waver until the passengers interfered with the hijackers' plans.

For the twin towers all you have to do is follow the Hudson River or the Long Island Sound. On a clear day it's not difficult. It looks like the AA11 hijacker did this. Edit: It looks like UA175 followed the I-95/NJ turnpike, using Trenton as a starting point

I agree that they probably used GPS, VOR, etc., but it would not have been needed.

It's not as hard as you're makng it sound, to navigate on a clear day. All you need is to know what to look for.

Are you a pilot?

I've flown planes from Cessa 152s to King Airs, and have a little time in Boeing 737 level-4 simulators. They all have VOR receivers, and those things all work the same way. Tune the frequency, select the correct autopilot mode, and the plane will fly you there itself just in case you can't follow the visual indicator. It is just NOT that complex. I realize the flight deck of a 767 looks intimidating to the casual observer, but any private pilot could become comfortable with it with a little study. And at least some of the hijackers had simulator time in jets, so it would have been even less intimidating to them.

We also all learned in basic private pilot training how to look outside the window and follow a map. Your suggestion to ban GPS receivers makes me wonder if you are also in favor of getting rid of windows and banning maps.

It's also very possible that the hijackers' first demands to the pilots were "Take us back to Newark" or "Take us to Reagan National" and the pilots set the initial course. Remember that pre-9/11 the response to a hijacking was to do whatever you were told.

I am a commercial pilot, instrument rated, airplane land and sea. Trust me, the VOR receivers in a 757 and 767 do not look anything like the ones in the Cessnas that they trained on. Sorry, but getting a 757 to follow a VOR radial with the autopilot is complex for the uninitiated. Also, I am unaware of this jet simulator time that you speak of... not saying it didn't happen, but I had not heard that before.

What I said was that I am surprised that GPS receivers have not been banned. If you will recall, I said the really important factor was the locked and hardened cockpit door and the change in previous hijacking procedures to cooperate with the hijackers.

These guys took over their aircraft several hundred miles from their eventual targets. To the best that anyone can tell, they were not particularly familiar with the territory or terrain. To think that they did this by looking out the windows, following roads and rivers, is too simplistic. To believe that the "pilot" (there was believed to be only one partially trained pilot on each plane) managed to fly a jet for the first time in his life while figuring out the VOR/autopilot, reading a map... the more I think this through, the more certain I am that they had handheld GPS receivers.

Read the government report, these guys couldn't even use the cabin intercom without inadvertantly broadcasting on the COM frequency.

And the only flight that went back to its start was the AA 757 out of Dulles which eventually hit the Pentagon, so the "take me back" scenario is not supported by any of the evidence. In fact, there is strong evidence that the pilots on UA93 were incapacitated, perhaps murdered, and laid out in the forward galley. Yet tis plane was making a bee line towards DC after doing a 180 near Cleveland.

Let's not get too hyper either way about this... I am just expressing surprise that the TSA has never disallowed the use of GPS receivers aboard aircraft by passengers. Whether they were used on 9/11 or not, they could be used in the future to track an aircraft towards a precise location. They can be used with little training and by someone who is not familiar with the aircraft systems and avionics.

Hey, I love the moving maps and using a GPS aboard airliners... I am just surprised that I can!

How quickly we forget... they trained on jets - of the same type they flew. They were able to use the existing cockpit equipment.

Sorry, but this sounds to me like more chicken-little fear. I don't see any reason to ban GPS receivers, nor do I see them as having even a minuscule connection to security or safety.

I think the previous posts have already said it best - aircraft have windows and many also have moving maps for inflight use. People on the ground can track flights, and any pilot worth his/her salt can learn to use the complex HSI/'glass' navigation systems on commercial jets. Also, many of the older jets without updated panels (DC9s, 732s,733s, etc.) DO have plain Jane VOR/NDB receiving capabilities for basic radio navigation.

Let's not forget the availability of aviation charts and maps which can be used for visual navigation in VFR conditions.

Why not just handcuff all passengers to their seats? Sounds like a better solution. Think of the children!