Just FYI the person with the iphone 3g question, no there is no real GPS in the iphone 3g, just access to the AGPS tower based triangulation.

you don't get a real satlock so you can't use it inflight, as it won't have any GPS means in airplane mode.

Just plain wrong: iPhone 3G has a real GPS.

No. What would be pretty cool is if you were actually on a DL 777 at 55,000 ft. :rolleyes:

Not correct :)

Read this article on aGPS: http://en.wikipedia.org/wiki/A-GPS

Essentially, it's REAL GPS but with extra assistance from other sources. The phone can contact a server and get updated location tables of where satellites should be, which greatly increases the fix speed. In airplane mode, it loses the A portion, unless it has an up to date location table loaded.

Gpsinformation.net keeps a list of airlines that allow and disallow consumer GPS units.

ok interesting, I used to sale cell phones, and the GPS at that time was not accurate and called AGPS as well, I got stuck in old terminology I guess :D
This is more what it was: http://en.wikipedia.org/wiki/Radiolocation

1st generation iPhone did not have GPS (or AGPS), it used radiolocation as per your link. iPhone 3G has GPS and AGPS.

When GPS first came out I used my Garmin iQue all the time without any hassle or 'interference'. In fact, many FA's thought it was nice to see where we were and our ETA.

I always liked looking at our speed since 500mph isn't so common in my car:D

Those "belt and suspenders" people are, at least in theory, correct (I speak as someone with significant RF/Wireless EMI expertise and 20+ years experience). Some such receivers do have a habit of radiating on frequencies of concern, and given just how weak GPS signals are, such concerns should not be dismissed out of hand. There are well documented cases of certain XM receivers interfering with GPS for similar reasons.

The chances of this cauisng interference with the AC main GPS are low, but should not be dismissed out of hand.

This is a common misconception; as noted above, depending on the receiver architecture, unintentional radiation on the LO, IF, etc frequencies is a potential threat to other receivers, though with modern receiver architectures much less so than in the past. It would be better if you left such aparently definitive statements to those fully qualified to make them.

According to the article you linked above, some devices require the "A" portion of A-GPS and others don't:

It appears that the iPhone requires the "A" portion in order to secure the satellite lock and do the necessary calculations--so either the iPhone does not have the location tables loaded locally (as ScottC said) or Apple chose to have the Assistance Server do most of the calculations required instead of the local processor (which, since the iPhone contains a 400-MHz processor, I don't quite understand--maybe it's for power saving). In any case, I [surreptitiously] tried the iPhone on a couple of flights last week (on a carrier that specifically prohibits them...which shall remain nameless ;)), and it was unable to secure a satellite lock either in the Maps app or the Here I Am app (which surprised me, as I thought more GPS satellites would be visible to the device from 36,000 feet). Now I understand why. Still seems strange...

(FWIW, I tried it with airplane mode both on and off, just in case airplane mode shuts the GPS receiver down. Not sure if it does or if the Location Services switch operates separately from the airplane mode switch...)

and the iphone is among the ones that don't.

getting a gps fix in a plane is not that easy, even with a dedicated gps unit. the gps in the iphone is not as sensitive as say, a garmin 60csx with a sirfstar iii chip. if you weren't holding the iphone up to the window, it's not at all surprising that it didn't get a fix, and even then, i suspect it won't work that well.

Actually, I did hold it up to the window for a good three or four minutes during a couple of my tests, and still nothing.

It's the new DL777-SR71 :)

Airlines which OFFICIALLY APPROVE the use of GPS receivers during CRUISE
 

Found this online and thought I'd post it.

http://gpsinformation.net/airgps/airgps.htm

Thanks for the FOM reference. I may have to play with this on my next flight....