Mobile phone reception in flight

[WHBM]

This old chestnut again......

But I just flew London to Larnaca and inadvertently left my phone, in my pocket, switched on. I'm sure I have found I have done this before and never noticed any difference. But I was surprised on arrival to see I had a series of SMS messages :

16.17. Welcome to Vodafone Germany
17.02. Welcome to Vodafone Croatia
17.34. Welcome to Vodafone Albania
17.55. Welcome to Vodafone Greece
19.01. Welcome to Vodafone Cyprus

Cruising at normal altitudes throughout.

So it would appear that the mobile signals from the ground do penetrate the aircraft cabin at altitude, which others have denied before, and which I have not experienced either. Any others have this experience ?

[STBYRUD]

Doesn't surprise me - after all you're likely a lot closer to the cell sites than you might be on the ground - in rural areas its quite possible to be further away from the next transceiver tower than 10 or even 20 kilometers. Probably the phone had the toughest job since it probably had to max out its transmitting power to get a signal down to the base stations...

[dixi188]

WHBM.

If you had paid attention to the pre flight safety brief you should have noted the bit about turning off electronic devices.

It amazes me how many people on pax flights ignore the cabin crew brief and demo.

It is there for everyone's safety!

It is also very rude to ignore the cabin crew at this time.

Ryanair CC used to stop the demo if everyone wasn't paying attention. I don't know if they still do, but I think all airlines should do this.

Rant over.

Safe flying.

[STBYRUD]

I'm lacking statistics to back this up, but I recon that on an average long haul flight with 300 passengers at the very least five phones will remain on during that flight - without complications. Lets face it, the possibility of UHF interference is a faint one. If anyone was to take this properly serious there should be someone with a cell phone detector on board walking the aisle after boarding. People know about the ban, people have heard the announcements a thousand times, people forget that their telephone isn't turned off... WHBM made an honest mistake, whats with the lecturing? My oh my.

[Gin Jockey]

Wow, I didn't realise the wings will fall off if someone uses their mobile phone.

[usedtofly]

I'm with Gin Jockey, what's the big deal about 'phones? I sit in the front left and leave my phone on all the time! Even used it to call ops before now while sat in the hold. My experience has been that over a certain speed the network just can't catch up!

An aeroplane is full of computers, radios and telemetry, a mobile phone is simply another one!

UTF

[bigwullie]

Sit in seat 1a also and find that you lose reception above around 12000 feet.
Havn't missed the localiser so far because of incoming calls but what do I know?

[CEJM]

Bigwullie, which part of the world are we talking about?

Here in the UK it seems that the signal disappears between 1500 and 2000ft. (that is on the very few occasions I looked at it.)


Dixi188,

Yes, the safety brief is there for everybody's safety and you should abide it. But people do forget sometimes and you are not excluded from that. However when somebody leaves their mobile phone on during the flight it will have no impact what so ever on the aircraft.

Think about it. Several airlines a contemplating the idea of allowing passengers to use thier mobile phones during flight. The only thing required is a bit of extra equipment but no other changes to the already excisting aircraft systems. So in a year time you might be sitting in exactly the same aircraft as yesterday but now all 300 passengers may use thier mobile phone.

[18-Wheeler]

FWIW a few years back when I was flying for AAI in Malaysia, we had a 747 lose an engine in the cruise over Bangladesh, I think. The aeroplane was going from Hong Kong to Dubai I think, not important though.
The captain decided to divert to the company base in KL, and managed to explain well enough to the local ATC what he wanted to do, but couldn't get them to understand the need for them to pass the message of the diversion on to the company.
The F.O. managed to get an SMS away at 35,000' when his mobile phone briefly picked up a signal. It wasn't a reliable signal though.

[raffele]

To add my tuppence worth...

WHBM.

If you had paid attention to the pre flight safety brief you should have noted the bit about turning off electronic devices.

If you read WHBM's post again, he clearly states that the phone was inadvertently left switched on. We all know the rules and regs and no doubt WHBM adheres to them, but you can't tell him off for ignoring instructions when, at the time, he didn't realise he'd not turned his phone off!

[eagleflier]

Here in the UK it seems that the signal disappears between 1500 and 2000ft.

doesn't that depend on ground altitude

Several airlines a contemplating the idea of allowing passengers to use thier mobile phones during flight.

That would make flights a lot noisier especially in my part of Africa where people like to shout on the phone

[call100]

Yep, Ryanair to charge for mobile calls on it's aircraft.....
Ryanair launches in-flight mobile phone calls - Business Traveller

[STBYRUD]

Well, its a different story with a service like this - a picocell is created by an onboard GSM access point (which itself is connected to the rest of the telephone network via satellite) that prevents the phones from searching for a network with increasing Tx power but instead presenting them with a strong signal and drains the unsuspecting customer's wallet with horrendous roaming fees...

[Capetonian]

I imagine that the signal would reach upwards a considerable way as it is unimpeded by obstacles, although some operators apparently shield upwards in order to allow a stronger signal to go out horizontally - I was told this by someone whose company put up some of the mobile networks in Central Africa.

A 'friend of a friend' says he was on a flight between CPT and JNB crossing the Karoo in cruise, probably at FL 37 and he swears his neighbour's 'phone rang and the guy answered the call. Apocryphal? I don't know.

I was on a flight into NCL the other day and just after we started our descent over Sheffield, a phone rang, I'd guess we were at FL 20-25 at that point? Someone will have a better idea of that than I do.

[muduckace]

In fact studies are going on in the mass freight system to certify cellular devices that transmit position for tracking purposes. No contamination with aircraft systems has been observed. It is what we do not understand that we fear the most for this reasion I say we completely understand the technology we posess. The FAA just has a ignorant position as they are a bunch of uneducated civil service employees as pertains to the matter who are drowning in burocracy.

The airlines have no motivation as they make money off of the SLF communications systems they installed.

[411A]

A few months ago, approaching DFFO (BoBo-Dioulasso, Burkina Faso) in my trusty L1011, the cabin chief says...
'Captain, everyone wants to say hello to their families at the airport on their mobile.'
I say...'sure' let 'em have at it'
We're on the twelve mile arc to the ILS, and it is time for an automatic approach/land...and we do so.
No problems whatsoever....dual/dual works as advertised.
The folks on their mobiles in back?
According to the cabin chief, they all connected OK.

NB.
When the last pax deplaned, he handed me an envelope.
Inside, US$cash...as this was the end of a long series of charter flights.
ALL completed on time with our Lockheed airplane.

[archae86]

However when somebody leaves their mobile phone on during the flight it will have no impact what so ever on the aircraft.

Think about it. Several airlines a contemplating the idea of allowing passengers to use their mobile phones during flight.

I'm an Electrical Engineer, not a pilot, and spent several years of my career on reliability matters at a major semiconductor manufacturer.

As noted by others, a mobile phone desperately trying for a link can raise transmit power to levels which drain the battery at a rate which quickly heats the phone uncomfortably hot. This will not happen with the contemplated onboard picocell arrangements. That difference reduces a safety concern. While most lithium cells are reliable even under heavy load, a few contain defects which incline them to catch fire or explode in that case. So the cells contain safety interrupts, which stop things before they become beastly--when they work properly.

But if the cheese holes line up too well:
1. turned-on phone
2. very distant cell tower causes the phone to raise transmit power
3. lithium cell has inherent manufacturing defect so tries to blow up.
4. included safety device is also defective, so the attempt succeeds.

You now have a bit of passenger explosion/fire aboard. Still several more cheese holes to go before disaster.

I'm one who guesses the picocells will enhance safety, by greatly reducing the number of mobile phones transmitting at high power on portions of each flight. Which I suspect will outbalance any safety loss from increase interference.

With pretty much every laptop vendor having gone through lithium cell recalls induced by actual in the field fire/explosion events, the probability that both conditions 3 and 4 will obtain is higher than I'd to keep hoping we shall continue lucky to drop both 1 and 2 as barriers.

Oh, and yes, I do turn off my cell phone when instructed.

[Metro man]

TELSTRA Australias NEXTG system will work in flight. On the old CDMA system I had almost continious coverage down the east coast at FL190 with turbo prop speeds and regularly called operations or home.

Easier with a slow aircraft at lower altitude over a built up area than a fast aircraft at high altitude over sparsely populated country. Type of aeriel makes a difference as well, some Australian phones are designed for country use.

Some pilots are using smart phones to log into the MET office radar read out whilst in flight and avoiding the storms.

[18-Wheeler]

Some pilots are using smart phones to log into the MET office radar read out whilst in flight and avoiding the storms.

Well it'd be far more reliable than any radar fitted to any Metro I ever flew!

A mate of mine used to fly MU-2's across Bass Straight, and with his old analogue mobile he could talk all the way across, except for about five minutes or so right in the middle. Can't do that with a modern mobile.

[halas]

Years ago with old analogue system, anywhere in WA at 25,000' got a signal. It worked even better with the windshield heat off.

halas