No GPS receiver allowed on Virgin Atlantic?

[snowyfish]

On a ATL-LHR flight the other day I noticed that the Safety on Board cards said:

"Global Positioning System (GPS) and intentionally transmitting devices e.g. radio pagers, satphones, radio transmitters [blah blah] must not be used at any time."

Now I can understand that most of the gadgets listed might cause interference and therefore shouldn't be used, but GPS? AFAIK a hand-held GPS device is passive with signals going from the satellite to the receiver only, therefore doesn't present any more risk of interference than a mobile or lap-top in flight mode, which are permitted.

Or do VA fly some magical route that they don't want anyone to know about?

[fa2fi]

They're not the only airline to specifically forbid their use, but with a moving map feature I've no idea why you would need to on VS.

Instead of specifically forbidding the use of GPS devices most airlines will simply not include them in their list of approved devices, and non approved devices are not to be used at any time and thus if GPS units are not on the list then they don't get used. They may be passive but they are still receiving a signal which is where the interference issue may come in to play.

It is the same on BA "Any device that transmits or receives communications but does not have a ‘flight safe’ mode, must be switched off for the duration of the flight" and neither easyJet or BA include GPS devices as an approved device.

It seems Vs is making it crystal clear that they are not allowed. That's my understanding anyway.

[S.o.S.]

snowyfish Welcome aboard the cabin of PPRuNe.

If you look through the http://www.pprune.org/passengers-slf...slf-forum.html so carefully prepared by my predecessor, you will see your question there..


Bear in mind that you have a legal obligation to follow the instructions of the airlines and their crew.

[TightSlot]

Please also remember that you may be contravening U.S. FAA regs and therefore breaking the law: Americans are twitchy about such things in the wake of 9/11 and one can well understand why. In short, if you choose to ignore the restriction, and are caught, you would be dealing with the FBI rather than the airline. That would probably not be a fun holiday experience.

[Basil]

Arrrh, Snowy lad, tis forbidden to know the ship's position lest ye motley swabs do mutiny and seize her from her rightful cap'n to go a'piratin'

[Delight]

I have a GPS on my phone that still operates in flight mode, but it never gets a lock on any sats. I assume that the airframe acts like a Faraday cage (even though it isn't earthed).

[kenparry]

I assume that the airframe acts like a Faraday cage (even though it isn't earthed)

A Faraday Cage does not need to be earthed.

See Faraday cage - Wikipedia, the free encyclopedia

[EEngr]

The prohibition could very well be due to the possibility of RF interference. Most receivers have a local oscillator (LO) which is mixed with the received signal to produce an intermediate frequency. Some poorly designed receivers/mixers allow this LO signal to radiate back out the antenna. Here, the danger is that this signal would be mixed with the sattelite signal in the avionics GPS and produce spurious results.

If the fear is that passengers will know the aircraft position, then what will they do as inertial navigation systems become accurate enough and are incorporated into personal gadgets?

[Agaricus bisporus]

With respect I can't believe anyone actually believes that "they" don't want us to know where we are. (If so why would "they" allow windows?) Or GPSs for that matter.

That's straight from "we are controlled by lizards" territory.

LFOs and interference are the reasons.

[snowyfish]

Right, got it!
S.o.S. - thanks for the pointer, I promise I did try the 'search' function before posting .... anyway I see the subject has been covered many, many times.

Cheers!

[S.o.S.]

Thanks snowyfish. Many threads include many subjects and getting them all in the same place is impossible.


Do stay and contribute to our forum 'cabin'.

[Basil]

A Faraday Cage does not need to be earthed.

I didn't know that.

I first had the effect demonstrated when I built a radio receiver which failed to receive. Our techs tried an RF sig gen and 'scope on it - worked OK.
Took it home in disgust; it worked.
Ah! Steel framed workshop

[KelvinD]

I have worked in radio for 50 years and every Faraday cage I ever worked in was indeed earthed. And to a pretty rigorous standard too.

[MarcK]

Then, there are personal faraday cages...

[Davef68]

Back in the day pre-wifi, before smart phones existed and other portable/handheld transmitting devices were uncommon (and therefore only phones were banned) I tried to use my satnav on a flight just out of curiosity. Couldn't get a signal.

[kenparry]

every Faraday cage I ever worked in was indeed earthed. And to a pretty rigorous standard too.

Depends how you want to use them. The Jet Provost T3 & T4 had fibreglass wingtip fuel tanks. After a couple of years' service, one aircraft had a lightning strike on a tip tank, with spectacular (though fortunately not terminal) results. All the tip tanks were then fitted with fairly crude Faraday cages, just metal straps around and along the tanks termintating in a fitting at the back end for tightening the whole assembly. It worked, though clearly not earthed.

[JimR]

Many, many years ago I was passenger on a trans continental flight before GPS receivers were common place. I had recently bought a portable GPS receiver. I asked the flight attendant if I could turn on the GPS in order to follow the flight (it was an FCC approved model). She said that she would have to ask "the guys up front". She came back with a big grin saying that sure I could use it, but the "guys up front" would like to take a look. So there I was with my new toy and an enthusiastic crew because they could now file direct rather than follow the zig zag VOR path. The batteries ran out before reaching destination but that was no problem since the crew just reverted back to normal navigation. Interestingly, it worked well in the cockpit environment - 737, but I guess the larger windows helped. Happy memories!

[timmcat]

Although admittedly risking getting my wrists slapped, I've 'accidentally' left the GPS switched on on my tablet on a couple of occasions (last time last weekend on a 767) whilst sat in a window seat. Took a good 10 mins to get a signal each time but it ultimately did with patchy results, sometimes only getting a single fix then unable to refresh, other times a good constant lock until I quit the map app.

[justawanab]

Had an embarrassing moment with GPS on a flight a few years ago when I started my iPhone GPS based "Speedo" app "just for fun". It took a while to get a fix but when it did started to sound it's quite strident alarm! I'd forgotten that I had it's speed warning set to 80kph. We were doing over 800!

I didn't know GPS wasn't permitted during flight. I also assumed it was passive.

I have a very neat set of photos taken with an iPhone through the window of an A380 over Turkey which are all neatly tagged with their location. Pity not to be able to use that functionality.