GPS on Planes?

[Old Goat]

Hello Group,
No, it's not like "Snakes on Planes".
I have a LONG flight taking place next month, and I was just mulling over a scientific possibility.
Even on shorter flights from the Midwest to DIA, I would like to know the names of the cities and towns over which I am flying.
In February, I'm flying to Santiago, Chile. I would love to be able to use my little eTrex Legend and an atlas on the plane. Looking out the window would make so much more sense with that set up.
My question to the more-technology oriented among this group: Can I get my little GPS to work in that type of a closed space if it is in the window? ..... just like how it can work on the dashboard of a car?
Thanks, Old Goat

[somethingrandom]

Sorry but I am likely to piss in your Cheerios and am not doing it with the interests of being an ass, but that of being a pilot for the last 11 years and air traffic control specialist (marginally special haha).

Yes. It will work. No, the accuracy will not be decent whatsoever (Unless of course you have an aeronautical GPS capable of discerning altitudes of up to 42,000' or so, to which I have not seen one capable of being handheld and self sustained)... MORE IMPORTANTLY, it is not an "approved electronic device", as it continuously transmits/receives signal. Not only is it illegal to use in flight, but it may also distort and/or interfere with controls on the flight deck. Get a good high altitude map and look out the window Or better yet, if you happen to be flying United as they do fly the route, when you get on the plane, ask the pilot/first officer greeting people if he/she would be so kind as to turn on Channel 9, and you can listen to all ATC communications and this should give you a very good idea of your location with a lousy map.

[Doug Shaw]

MORE IMPORTANTLY, it is not an "approved electronic device", as it continuously transmits/receives signal. Not only is it illegal to use in flight, but it may also distort and/or interfere with controls on the flight deck.

The eTrex Legend (like most consumer-grade handheld GPS units) is not a transceiver, it is only a GPS receiver - no transmit. The GPS satellites are raining down those scary electromagnetic "plane crasher" waves on the aircraft whether the GPS is present and turned on or not.

I'd be more worried about people who have been living in a state of perpetual fear beating the crap out of you for turning on a "suspicious device", and then being arrested by foreign authorities the moment the plane touches down.

None of which actually addresses the OP's question, of course.

I'd expect that the plane's metal body would act something like a Farraday cage and basically block a lot of the signal, but I don't know for sure...

[Old Goat]

I had always just viewed a hand-held GPS as a passive receptor of satellite-emitted radiation - kind of like a transistor radio that picks up multiple signals but doesn't send out in response.
Your understanding is that a hand-held GPS is more like a cell phone or iPad or PDA that can also emit electromagnetic radiation that might interfere with cockpit signals.
This is interesting. What types of electromagnetic radiation does a GPS emit? ....and why?
Thanks, Old Goat

edit....I was typing while Doug was answering

edit 2 ...good points, Doug. I'm now envisioning a stewardess with her Taser aimed at my noggin while I'm setting a waypoint. Maybe the GPS on the plane is not such a good idea, after all.

[Markwise]

With all due respect to our pilot friend, I've used my Garmin Nuvi on a plane several times and out of my consideration for the rules even asked the flight attendant if that was permitted. I was told yes, go ahead. And so I have had my Nuvi sitting out on my tray table for several flights in open view of all flight personnel. Signal quality has been descent if I keep it near the window.

Mark

[coloradokevin]

Sorry but I am likely to piss in your Cheerios and am not doing it with the interests of being an ass, but that of being a pilot for the last 11 years and air traffic control specialist (marginally special haha).

Yes. It will work. No, the accuracy will not be decent whatsoever (Unless of course you have an aeronautical GPS capable of discerning altitudes of up to 42,000' or so, to which I have not seen one capable of being handheld and self sustained)... MORE IMPORTANTLY, it is not an "approved electronic device", as it continuously transmits/receives signal. Not only is it illegal to use in flight, but it may also distort and/or interfere with controls on the flight deck. Get a good high altitude map and look out the window Or better yet, if you happen to be flying United as they do fly the route, when you get on the plane, ask the pilot/first officer greeting people if he/she would be so kind as to turn on Channel 9, and you can listen to all ATC communications and this should give you a very good idea of your location with a lousy map.

I've also been a pilot for 11 years, though I'm only an instrument rated private pilot (not sure if you fly professionally, or just recreationally like I have... I was planning on a professional move when I started, but 9/11/01 kind of put a damper on my career prospects at the time).

With all due respect, handheld GPS units are receivers, not transmitters or transceivers. Also, though many of the aircraft I've flown have IFR approach certified GPS units installed, I've still played around with my handheld unit during some of the flights that I was piloting. The GPS had no effect on the nav/com electronics of these aircraft, even when it was held within inches of the equipment. I'd bet a paycheck that it absolutely won't have ANY effect on the electronics of an airliner, particularly when used in the passenger cabin area of that aircraft.

If you can acquire a GPS signal, which may or may not be easy depending on the build of the aircraft, I suspect that the accuracy would be just fine. As I'm sure you know, IFR certified GPS units are quite expensive. Then again, so is a simple digital clock if it is approved for installation in an aircraft. However, that doesn't mean that a hiking-oriented GPS won't provide decent data for the purposes of air passenger satisfaction. Accuracy is more a function of the satellite signal than anything else. Mind you, I won't be using my Foretrex to fly an instrument approach, but I can't see why it would be problematic to use it for fun while acting as a passenger.

[yosemite98]

handheld GPS units are receivers, not transmitters or transceivers

This is a true statement. GPS receivers don't transmit anything (who would be listening? certainly not the satellites), unless you're talking about a SPOT receiver or something like that. It receives each satellite's time and position and then calculates your position based on that data (you need 4 satellites minimum to solve for the X,Y,Z, and time variables).

I've been using my GPS since 2000 in airplanes, although I was a little wary after 9/11. It does a pretty good job with speed and location, except when I was over the Pacific on my way to Hawaii, then it showed me close to Alaska, instead of west of San Fran... That was pretty funny and kept me entertained for a while!

[Old Goat]

Thanks for the replies. Now I hope that I can bounce my buddy out of the window seat, so that (weather and daylight permitting) I can know which of the Andes' "tall boys" are in view or the names of the cities and towns below.
p.s. I had read in quite a few postings on 14ers.com that a few of you carry GPS units on your climbs. That is why I posted the question here, for my fellow mountain geeks who are also technology geeks. It's good company.

[KentonB]

I have some personal experience in this area, so I thought I'd reply...

First, GPS Units themselves are not "illegal" on planes per se, but they do violate many airline's internal policies. Failure to comply with the airlines policy (and/or request) could get you in trouble and those actions would be illegal. It is up to the airline and/or the pilot to approve or disapprove their use on the plane.

That said, I was flying several years ago and showing the guy next to me my new GPS device. By today's standards, it is archaic, so I actually had trouble getting a signal without holding it next to the window. A stewardess saw this and I think she nearly had a heart attack (not knowing what it was). After I told her it was a GPS unit, she showed me in their airline's policies that GPS units were not allowed to be turned on during flight. I complied.

Today's GPS units (with high-sensitivity receivers) receive GPS signals much better than the unit I had and likely wouldn't have any trouble on a plane. Assuming good satellite coverage, positional accuracy should be just as accurate at 42,000 feet as it is at zero. In fact, without ground clutter, it might be better! GPS satellites find your position in 3D... so altitude is not a problem (unless you're higher than the satellite belt itself).

-Kent

[KentonB]

Quick "addendum"...

While it is true that most GPS Devices are receivers, ALL electronic devices emit some RF (by virtue of being electronic). I've read studies that show GPS Devices emit some of the lowest RF emissions (compared, say, to laptops). The things run on 2 AA batteries after all!

-Kent

[yosemite98]

GPS satellites find your position in 3D... so altitude is not a problem

This is true, the problem I had might be the maps and earth model used on the receiver, especially over the ocean (just guessing). Being at such a high altitude, it might not have correlated correctly when it tried to project my position on the ground/ocean. I was using an older Etrex Vista (2000 model) that didn't have good maps to begin with, so newer receivers might do better.

[Doug Shaw]

While it is true that most GPS Devices are receivers, ALL electronic devices emit some RF (by virtue of being electronic). I've read studies that show GPS Devices emit some of the lowest RF emissions (compared, say, to laptops). The things run on 2 AA batteries after all!

Yes, but (almost) nobody believes that standard RF leakage from devices is a real problem - we're allowed to use laptops and other electronic devices while in the air.

I'd wager that if one were able to obtain real usage and configuration statistics about the devices people use on aircraft, it would demolish the idea that these devices will interfere with the plane's operations. A large percentage of people don't know how to turn off the wifi on their laptop or ipod or phone, or put the phone into airplane mode - yet these things are out and in use all the time. There have got to be hundreds of thousands of people a year who fly with their devices transmitting in the blind with no adverse side effects on the operations of the aircraft or air traffic control. Certainly there would be far more people who do it than incidents caused by people who do it.