I thought of posting this in The Great Ongoing General Aviation Thread, but thought I’d get a factual answer here. Maybe this thread can be merged after there is an answer? Or else I could post a comment in the other thread.
The FCC prohibits use of mobile phones on commercial airliners. I’ve heard that the reason is that the jets travel so fast and high that it messes with the system. But what about a private (General Aviation) plane? If you’re puttering along at 130 knots in your Bugsmasher 160, I can’t see that it would cause problems with the signal bouncing from tower to tower. I don’t think there would be a problem at 3,000 feet AGL. What about 10,000? Or 12,000? Most ‘little airplanes’ don’t get much higher than that.
What are the rules regarding cellular phones in light aircraft at low altitudes and airspeeds?
There is a Federal Regulation from the FCC that prohibits the use of cellular telephones in flight. It reads as follows:
Note, the CFR does not distinguish between Part 135 operators and the rest of GA. I wasn’t able to find a definition for aircraft in my very brief look through Part 22, but it seems clear from the text that the FCC meant to include anything that could be considered an aircraft. Whether they have the authority to make this particular regulation, or whether the regulation is arbitrary or capricious: all are separate questions. Also, what the penalties are for using your cellphone while tooling around in your C172—besides “could result in suspension of service and/or a fine”, and how much of a priority enforcement is for the FPTB, I don’t know.
I note accessories such as this bluetooth adaptor for cell phones that works with a variety of aviation headsets, so I doubt you’d be the only person who’s ever used their phone in flight.
The concern is more with onboard avionics and communications equipment; it’s plausible that any given cell phone could cause interference problems with onboard equipment leading to an incident or accident. And since it’s not feasible to test each and every cell phone+aircraft combination, there is a ban on cell phones (and wi-fi) on aircraft.
At least, from a safety point of view, that’s the idea. Aviation safety specialists tend to err on the side of caution; the inconvenience is recognized, but it’s not like there’s an easy fix. Telecommunications technology advances much faster than aircraft technology, and it’s just not possible to keep up. Lots of people say “show an incident where a cell phone caused a problem” and while that can’t really be done, who’s to say that any given temporary loss of communications or other avionics failure wasn’t caused by some person in the back sending a text message (yes, I know that’s a commercial example, but it’s what I know…!)?
I have used my cell phone in flight on general aviation aircraft. It, for the most part, worked just fine. We didn’t crash and all the instruments worked as they should. We had (thankfully) a compatible headset otherwise it would have been impossible to hear or talk over the noise.
I’ve been told (no cite) that early cellphone systems had problems when a phone was “in view” of too many cell towers, whereas the current story is that the system is smart enough to detect that you are hitting too many cells, and simply denies service to your phone.
My experience is that availability of service is a function of altitude, terrain and proximity to populated areas - which is consistent with the description above. If you get high enough, you’ll reach a point where service stops - but the altitude at which that happens will vary a lot.
You can make a weak case that “no mobile phone use in flight” makes sense - because it’s at least possible for the phone to interfere with some instrument or radio, and possible that such interference could be dangerous.
But it seems to me about like that old notion that cellphones need to be off when fueling your car, as they might cause an explosion. We seem to have got past that piece of silliness.
I don’t think the problem is with interference; the problem is that cell phones operate line-of-sight with a substantial range. Put yourself 2,000 or 3,000 feet up and in some areas, a huge number of cell towers are line-of-sight. Even on the ground, I’ve had cell phones reach almost 20 miles; presumably in the air, just as far or better. Plus, relative signal strength is what determines if the tower will talk to you or tell another tower to handle it; and you are tying up a channel (mux’ed) on all those towers.
The system was not designed for one cell to be broadcasting to the entire countryside.
The problem with airborne cell phones with respect to ground systems originally was not so much that they contact multiple towers simultaneously, but that they contacted multiple cell phone systems simultaneously. This wreaked havoc with the handover mechanisms in place between systems and caused calls to be dropped and often crashed parts of the cell phone systems causing all calls on those systems to be dropped. Cell phone users are pretty obnoxious, to the point where it often seems like the best way to guarantee that someone will use a cell phone in a particular spot is to put up a sign saying you can’t use a cell phone there. Because people in planes insist on using cell phones while in the air despite FCC and FAA bans, the cell phone companies have just had to cope with it. The systems were made much more robust, and airborne cell phones no longer wreak havoc on the ground. This hasn’t been a problem for many years now.
Airborne cell phones do still tie up communication resources on multiple towers, effectively reducing how many phones can be connected to those towers, so the FCC still doesn’t like airborne phones because they effectively waste bandwidth. For this reason, the FCC still doesn’t allow them even though they no longer cause major problems.
The FAA bans cell phones for two reasons. The first is because the FCC bans them. The second is because of potential interference to aircraft systems. The most common problem, at least according to pilots that I have spoken to, is squawking noises in the pilot’s headsets, which makes communication difficult. I am aware of a few cases where cell phones have interfered with navigation equipment on smaller planes. No one I have ever talked to has confirmed it happening on larger planes but it is theoretically possible. Interference with actual flight control systems is much less likely, though I am aware of one case where signals from a cell phone caused a thrust reverser to deploy.
The antennas on cell towers are directional. They send and receive signals much better in the horizontal direction, and are almost deaf vertically. This isn’t because they intentionally want to block out airborne signals. It’s just a cheap and effective way to boost their range without requiring more transmitting power. A directional antenna boosts the range in one direction at a cost of reducing range in other directions. Because the antennas are directional, airborne cell phones fairly quickly move out of the area of good reception. Cell phones will typically get a decent connection up to somewhere around 3,000 to 5,000 feet. Above that, their ability to connect drops off fairly quickly, and it’s almost impossible to get a cell phone to connect once you get above 10,000 feet.
Without commenting on the legal situation in any jurisdiction, I will just note that I always leave my mobile phone switched on while flying. My reasoning is that in the event of an emergency landing I may need to use the phone on the ground to call the emergency services. If I am injured, the extra time and difficulty of switching on the phone may make the difference between successfully making the call and not.
While there is potential for minor interference with radio communications (beep b’beep beep b’beep beep every 15 minutes or so), I can conceive of no possible way that the phone in my pocket could cause an accident when flying VFR.
In the event of an emergency landing, the pilots have probably already called a Mayday and switched the transponder to an emergency broadcast. With ground impact, the ELT would be triggered, it can also be triggered manually by the flight crew as well. Underwater locator beacons also trigger on the black boxes when they are immersed - there has only been one case of those not working/not leading to the wreakage being found (AF 447) and you wouldn’t have been able to make a phone call in that case.
Compared to the plausible risk of the emergency landing being due to malfunctioning onboard avionics (there is one version of Honeywell PFDs that are currently known to blank out when wi-fi systems are used… the pilots lose most of the information they use to fly), do you really think the time needed to boot up your cell phone is something you can’t afford to take were you to survive a crash?
It’s a nice rationalization, but IMHO it doesn’t pass a risk analysis.
hibernicus used the phrase “when flying VFR” which suggests he’s talking about a plane that he’s flying - not a case where he’s an airline passenger.
But it raises an obvious point: If you tell passengers to turn off their phones, many will do so, some will forget, and some will deliberately ignore the instruction. So if there’s known to be any real chance of a problem, it’s extremely irresponsible to rely on voluntary compliance.
Sorry I didn’t make myself clear. I want to emphasise that when travelling as a passenger in a commercial airliner, I am happy to follow the rules and switch off my phone before stowing it for the duration of the journey. I don’t for a minute condone anybody ignoring safety instructions.
My post, as Xema explained better than I did, referred to a situation where I bear sole responsibility for my own safety, and if I need assistance I am the one who will have to call for it.
Ah, that makes more sense. If you are the pilot, there is logic in having all available resources in an emergency, and I think that an experienced pilot can test his/her plane with his/her cell phone and see if any glitches occur in normal flight, but in theory, it’s not so easy as most pilots won’t do every test airworthiness validation would require and an unusual situation could still arise in which a problem due to interference occurs.
As I said, cell phone technology changes so fast, and aircraft technology changes so slowly that it just isn’t feasible for the latter to stay up-to-date on the risks posed by the former. Your current cell phone might be fine…the next model may cause your radio to static, the one after that might accidentally screw around with your transponder. There’s no one answer, because we aren’t talking about a single type of phone.
From a practical aspect, for private light aircraft, I have never had a pilot have an issue with it nor have there been any resulting difficulties other than the higher up we get the more it drains my battery–I think due to searching for a signal. Experiences in Cessnas (various), a few Bonanzas and a Cirrus (once and we didn’t need the damn shoot )
Same for the bigger planes too like King Airs, Citations, etc. Wish I knew about the G5’s and 6’s.
One side issue that would always come up on the pilot forums when this is discussed that is that there was a faction who thought the FCC regulation was narrowly written in such a way that technically it only applied to older cell phone technologies, not the current transmission protocols, and had never been updated to cover the current protocols. I’m not enough of an EE or an RF expert to know if they were completely right or if this was the engineering equivalent of claiming the income tax is illegal.
That being said I can sometimes tell when someone has a phone on in my small plane. When I’m at an airport with an actual primary target radar spinning around I hear a chirp in my headset when it points at me. When someone has a phone on in the plane that radar chirp is much louder. I don’t have the slightest clue what would cause this, but that’s the only affect I’ve ever been able to discern from having a phone on in the plane.
A CFI with the FBO at the Class C airport I fly out of occasionally told me the following story.
He was returning from a cross-country with a student in one of their Light Sport Aircraft (LSAs). The radio failed. He flew around the pattern waiting for light gun signals, but none ever came. Eventually he took out his cell phone and called the tower. The tower controller told him their light gun was from the 1940’s and not very bright, then gave him a clearance to land. On roll-out the tower said that, in the event of radio failure, calling them on a cell phone is the best choice.
As a small plane pilot, no one has ever been foolish enough to disobey any suggestion I have made. Well, and stay on the airplane.
Never had a boss that stupid either, all backed the pilot 100%
Way back, when patrolling pipe, one company had big heavy Motorola phones that we threw behind the seats but within reach that we could dial an actual rotary dial and get the dispatcher. ( Not a regular phone number though. ) Used a separate mic and speaker. 1969 -1971 time frame…
All the more reason why cells get confused; instead of a group of towers around the actual location getting the signal (with the assumption - the strongest signal is in the center) the system will detect a hollow ring of connections, the ones on the horizon will get your signal and the ones directly below you will not.
Signals are handed off based on when the signal gets louder at an adjacent tower than at you current one as you move from zone to zone. If instead the “loudest” hops all over the map with no logic, the system will get confused. The lesson of 9-11 of course, is “not so confused that you can’t make calls”.
Oh, and a signal every fifteen minutes?? No, your phone pings the cell every second or so with a “hello I’m still here” packet, just so the system knows which tower to route your calls to within a secnd or two… Or that you switched off your phone. It doesn’t just go on a hunt from any possible tower when the call comes in.
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