Mobile phone when airborne
 

I have an iPhone5 with Skydemon. I use it as my default GPS as it's small, I can clip it to my kneeboard, it has built in GPS and works a treat (I carry two others GPS's as well). I don't use the phone to make calls or anything when airborne but obviously I can't have it in airplane mode as the in built GPS wouldn't work. What's the score on using these from a legal point of view re jamming masts etc? I can't imagine Skydemon releasing an app for the iPhone if it wasn't above board.

I frequently text an ETA to my hosts when flying on a longish trip.

Jamming masts? I don't really care if it does! I pay £40 PCM for my contract and if I can't use it during my day to day living that's their problem.

Is it safe?

Well, a 5 second text and then reverting to true VFR IMHO is much safer than having one's head glued downhill for hours on end to an iPad with SkyDemon installed, like some people seem to choose to.

Mmmm, back to the original question...

No,

Using an iPhone based GPS app will not jam masts.

Thank you.

Are you sure your phone's GPS won't work in Flight Mode? My Android phone works fine as a moving map GPS in Flight Mode. Maybe it's just an Iphone thing. :sad:

MJ:ok:

I mostly fly in the late afternoon/early evening so leaving the phone turned on and in normal mode is a must in case any friends or family are calling around trying to organize a Salvador.

No, you get the orange plane of doom instead of the yellow plane of hope.

On a legal point I understand using a mobile phone may contravene the Wireless Telegraphy Act since all transmissions from an a/c should be from an approved installation - which a mobile phone is not.

There is also a potential distraction factor if it rings whilst in a critical stage if flight.

You mean you can actually hear your mobile phone ringing in flight? Are you a glider pilot?

So basically iphones are rubbish, if you just get an Android phone then the GPS works just fine in flight safe mode.

I often forget to turn mine off, worst case is the annoying electronic noise on the intercom, can be quite embarrassing if it does that while you're making a call to ATC.

As for jamming the masts, I don't think it creates a massive problem from the low levels of a few thousand feet, after all you could be up a hill and be that high, my understanding is that it's a problem when well in excess of 10,000' and you end up in a "white zone" where you can connect to multiple masts at once which the system wasn't designed for. I although I also hear that the more modern systems are fixing this, pretty sure we'll all be able to make phone calls on passenger flights in the not too distant future.

How do you lot get a mobile service when airborne?

I lose service climbing through 100ft.

My understanding is that it's not illegal, otherwise pilots who have lost comms in flight who then decide to use a mobile to communicate with people on the ground would have been prosecuted before now.

Fats

With GSM there is a problem in that the protocol assumes the signal takes less than a certain time to go between mast and phone. If the signal takes too long it does not work. I seem to remember the maximum distance is ~15NM.

So when airborne one's phone may try to communicate with a mast more than 15 miles away and then give up completely even if there is a mast closer.

In my experience flying at 2500' or so results in an intermittent connection. Sometimes one can have a proper conversation with a bluetooth headset but expect to be dropped any time. It is usually possible to get a text out but it may take several tries.

The GSM modem in an iPad gives weather/NOTAM updates via Skydemon .... but again intermittently.

The actual behaviour varies according to where you are. As stated, above 1500' or so in UK usually means no connection. Often plenty of bars, but no data.

But in NZ any VFR level and virtually anywhere in the country means good data. Same in the Western US within 10-20 miles of a settlement (all this GSM).

In N Europe usually same as UK, but South of France similar to US.

Presumably all this is related to the local topography. Maybe presence of users at higher elevations means the signal has to have a greater vertical coverage?

I made a call at 5000ft a few days ago over Stroud, not something I've done before so no idea if it was a fluke

I've read reports here of it also causing the VOR needle to point the wrong way.

But of course as you're using the phone to navigate in IMC you don't need the VOR so why would you care? :D:):ok:

My recollection is 35km (I've got a large pile of the ETSI/3GPP standards on my desk, the details are in there somewhere, but I'm afraid I'm not going to go looking right now).

If the phone is a long way from the mast it has to transmit its signal early so that the mast receives signals from all phones properly slotted together, and there's a limited number of bits in the protocol for telling the phone how early to send its signal. Plus, before you get that far, there's a limit to the amount of slack in the timing for the initial contact from the phone (before it's been told how early to transmit).

GPS
 

The GPS mode of your phone is simply receiving signals from the
GPS satellite network to work out your position. It doesn't involve
any phone transmission,

-- Andrew

Unlike the iPad where the inbuilt GPS works in 'Airplane Mode', the iPhone GPS does not. I've read that this is because GPS and GSM/LTE use the same chip in the iPhone.