Anyone have a GPS and do you use one? Also, are they legal to use in flight (sorry, I don't have page 82 of the magazine in front of me). What brand/model would you recommend?

GPS use is ok on United and British Airways, but not on several other airlines. http://joe.mehaffey.com/ is the main resource for GPS questions and has a list of which airlines allow GPS and which don't.

It can take a while for a GPS to sync up at an airplane window (due to poor satellite configuration, multipath, and doppler shift) but it usually works. It has to be right at the window (though the blind can be closed). I was having difficulty one time (in United FirstSuite, where the seat is a long way from the window) and an FA lent me an external amplified antenna--which significantly improves reception (who says you don't get great service from the FAs on United?). I bought an external antenna for myself after that, but seldom take it now, even though it offers the conveience of attaching directly to the window with suction cups, 'cos it's one more thing to carry.

I don't use GPS inflight so much now that map displays are common on the IFE.

Garmin are the most popular brand. I use a Garmin IIIplus, the Garmin Emap is another popular choice. A GPS receiver is the most complicated consumer device you will encounter--it takes months to learn to use all the functionality (waypoints, routes, tracklogs) to full advantage. It's also one of the most fun toys there is.

A good place to buy Garmin stuff (no connection, just a satisfied customer) is http://www.tvnav.com/navhome.html

[Edited to add TVNAV link]


[This message has been edited by someotherguy (edited 12-16-2000).]

Someotherguy:

Thanks for the link, I've always wondered if they were allowed or not. I was told several several years ago (by a pilot) that if you tried to turn one on once in flight, it would never get a "fix". But, you are the second person in a week to tell me that they will work if you hold them up to the window.

BTW. OfficeDepot has the Garmin GPSIII+ (usually $345) on closeout at $99. To get full benefit, you also need Garmin Mapsource maps (downloadble streetlevel detail), which cost $80 per country.

The only time I've not got a "fix" was on Concorde. The FA suggested it might work better in the cockpit, but it didn't .

Do you have documentation from official UA docs or the UA web site that says that GPSs are allowed? The reason I figured they were not is that their announcement says "any device that transmits or receives is not allowed at any time". This is in contrast to Alaska, which explicitly states that you must shut off GPS receivers at takeoff and landings.

I've regularly used my GPS on board for several years. I also regularly connect it to my laptop and run StreetAtlas. It's really cool to look out the window and say "Hmmm... SR50 and SR6, East Ely, NV." On most planes, I can "stick" my external antenna between the window and the shade. Sometimes I get a solid lock right away. Other times it takes 30-45 minutes, and then only for an intermittant fix.

I used to always ask the crew if I could use it, but it just got the point where the answer was always "yeah, sure." The best response, after the FA asked the captain, was "Sure, and if you could figure out where we are, please let us know."

I use a Garmin eMap on board Delta flights all the time. As long as I hold it next to the window, I never have a problem getting good reception from the satellites.

My second flight with my eMap was from SJC to SLC. I had just boarded and pulled out the eMap and was holding it up to the window to get a fix -- I've found it syncs up faster if it has been recently turned on.

I heard this voice say: "We are at the airport."

I turned to the aisle and saw a FA standing there. Not knowing what she meant, I responded "Huh?". OK, so it was early in the morning.

She pointed at my GPS and said: "In case you were trying to figure out where we are, we are still at the airport."

Cute.

--John

How 'bout for driving, say in a rental car? Any recommendations for GPS in the USA? I always get lost and I don't rent from Hertz, preferring Avis

Have also used a friends GPS on board AA, no problems from the flight crew to use.

I routinely use my Garmin eMap during flights, and have never been told to turn it off. Several flight attendants have asked what it is, and several have asked jokingly "Are we going the right direction?"

The 2-dimensional locator is quite accurate, but you can't get a lock on enough satellites from the tiny window to get an accurate elevation. 35,000 Feet often varies by 500 feet or more.

The inflight maps tend to only show wide area maps. You still need a GPS to know what a particular road, town, or river is.

Does anyone have a favorite GPS?

FYI, there are three reasons that GPS altititude varies from the aircraft's altitude.

The primary reason is that above 18,000 ft., airlines change the barometric pressure on the altimeters to 29.92. Altitudes above 18,000 ft. are called Flight Levels, indicating that the altitude is not true, but is the altitude that cooresponds to this barometic pressure. Among other advantages, using 29.92 universally above 18,000 ft. allows airlines to maintain appropriate vertical separation without having to adjust the barometric pressure every 100 miles or so.

Secondarily, GPS altitude variation is roughly twice the level of horizontal variation. If you get an EPE of 100 ft., the altitude error can be as much as 200 ft.

And finally, GPS altitude is the altitude over a theoretical simplified spheroid of the Earth and can vary from the real altitude over the Earth.

Also, I wholeheartedly recommend http://joe.mehaffey.com for comprehensive info on GPS!

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My Aviation Pages
My Travel Pages

I am a big fan of the Garmin handhelds. I like the GPS III Plus for the technical information you can get out of it, but the eMap is also nice for step by step directions.

I've got a couple of GPS pages, if you're interested: http://www.bollar.org/garmin.htm

AA, unfortunately, banned GPS use earlier this year. The form letter they sent me back that it's banned for the same reason as cellular phones, which is a specious argument. I wrote back asking for clarification & did not receive a good response.

Any 12 channel GPS, connected to a laptop running Street Atlas. There are other mapping programs, but I prefer (and I think most do) the Delorme products. Not perfect, but very effective.

The new "Road Warrior" edition looks interesting, with voice commands and responses. A big improvement while driving.