Aircraft instrument interference from cellphone
Jul 20, 2012, 3:13 pm
#1
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Aircraft instrument interference from cellphone
I know the topic of prohibition of electronics during take off and landing comes up fairly often, but here's a case where it looks like it actually makes sense.
So admittedly cellphones are designed to transmit and many electronics aren't (although kindles/nooks/etc usually at least have Wifi or the like), but I think we can all get the appropriate message from this ASRS report: never fly on CRJs. 
A CRJ flying at 9,000’ received an EFIS COMP MON caution message:
“Flight Manual directs pilots to slew compass to reliable side. It was apparent neither side was correct with the Captain’s, Mag Compass, and First Officer’s headings all different. We were cleared direct to a fix. Multiple attempts were made to match the headings with only temporary results. The Captain elected to hand fly while the headings mismatched. While the FMS was taking us in a direct line, with the wind shift while hand flying the aircraft ended up 4 miles south of the original ‘direct to’ course. ATC called and asked if we were going direct, I told them we are having heading problems and asked how our heading looked. He told us 10 right and direct when able. On this trip we flew this same aircraft for 9 legs and did not have this problem on any other flight. In the past I have had similar events with speculation that cellphones left on may contribute to the heading problems.
The first Officer made a PA announcement asking everyone to check their cellphones and the flight attendant walked through the cabin. Sure enough, in Row 9 was a phone in standby mode—not airplane mode. The passenger said he didn’t know how to program that so the flight attendant showed him and as soon as the phone was secured, all the avionics worked perfectly.”
“Flight Manual directs pilots to slew compass to reliable side. It was apparent neither side was correct with the Captain’s, Mag Compass, and First Officer’s headings all different. We were cleared direct to a fix. Multiple attempts were made to match the headings with only temporary results. The Captain elected to hand fly while the headings mismatched. While the FMS was taking us in a direct line, with the wind shift while hand flying the aircraft ended up 4 miles south of the original ‘direct to’ course. ATC called and asked if we were going direct, I told them we are having heading problems and asked how our heading looked. He told us 10 right and direct when able. On this trip we flew this same aircraft for 9 legs and did not have this problem on any other flight. In the past I have had similar events with speculation that cellphones left on may contribute to the heading problems.
The first Officer made a PA announcement asking everyone to check their cellphones and the flight attendant walked through the cabin. Sure enough, in Row 9 was a phone in standby mode—not airplane mode. The passenger said he didn’t know how to program that so the flight attendant showed him and as soon as the phone was secured, all the avionics worked perfectly.”
Jul 20, 2012, 9:23 pm
#3
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Dunno. A report by an airline pilot or copilot of interference that ceases when the phone is secured seems like proof of the phone being the source, although you are right that it is anecdotal and the plural of anecdote is not data...
Jul 20, 2012, 10:41 pm
#4
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Just think about it. If cell phones could truly cause interference with the flight systems terrorists would just bring electronic devices on board that transmit waves so that they could interfere with the navigational systems. It would be so easy to do. It simply doesn't make sense that they would actually interfere.
As someone who's analyzed numerous scientific studies, I can say with certainty that you cannot make any conclusion whatsoever based on this situation. Even without knowing the technical aspects of navigational equipment and waves, there are so many other confounding variables that there's no way to tell what the cause of these issues was. One possibility is that they flew through a specific area that for some reason had interference of some kind. I'd like to see what happens when that same person travels on another flight with their phone in standby (or what would have happened if he put his phone back on standby).
As someone who's analyzed numerous scientific studies, I can say with certainty that you cannot make any conclusion whatsoever based on this situation. Even without knowing the technical aspects of navigational equipment and waves, there are so many other confounding variables that there's no way to tell what the cause of these issues was. One possibility is that they flew through a specific area that for some reason had interference of some kind. I'd like to see what happens when that same person travels on another flight with their phone in standby (or what would have happened if he put his phone back on standby).
Jul 20, 2012, 10:52 pm
#5
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Correlation is not the same thing as causation
Jul 20, 2012, 11:30 pm
#6
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I think the real point is this:
Put your cellphone in airplane mode when you get on a plane.
If you don't know how to put your phone into airplane mode, shut the thing off.
Put your cellphone in airplane mode when you get on a plane.
If you don't know how to put your phone into airplane mode, shut the thing off.
Jul 21, 2012, 11:01 am
#7
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Actually, the real point is that in over 300 million commercial flights in the last 30 years there is not one single proven case of interference by a consumer electronic device. Turn off your device if you want to save your battery, but that is all you will be doing, nothing more.
Jul 22, 2012, 6:18 pm
#9
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Just think about it. If cell phones could truly cause interference with the flight systems terrorists would just bring electronic devices on board that transmit waves so that they could interfere with the navigational systems. It would be so easy to do. It simply doesn't make sense that they would actually interfere.
Jul 23, 2012, 5:30 am
#10
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Or, more likely, if cell phones did truly cause interference we would have heard a lot more about it than a handful of apocryphal anecdotes, given the millions upon millions of flights and likely thousands or millions of cell phones left on by mistake over the years. And the TSA would ban cell phones along with explosives.
http://www.iata.org/pressroom/pr/pag...-24-10-01.aspx
The US alone has over 9 million flights per year http://www.transtats.bts.gov/
Over 2 billion pax per year. Estimate that 0.1% leave their cell phones on (probably a low estimate based on my observations). That's over 2 million per year. Pure coincidence easily accounts for a few instances in which it appears cell phones caused issues.
Jul 23, 2012, 7:43 am
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Jul 23, 2012, 8:21 am
#12
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Any transmitting device can bleed over if working improperly, much like the CB did in days of old when they go into the neighbors TV.
Secondary harmonic-es can and do put out a signal, most of the time it is not harmful, but their has been time it has need heard on TVs.. Ham Raido Cop Cars etc.
We use to have crystal radios, no tubes just picking up the transmission of radio stations.
Circuits are much better shielded and designed today...
Not too hard to find a transmitter so turn them off...
Secondary harmonic-es can and do put out a signal, most of the time it is not harmful, but their has been time it has need heard on TVs.. Ham Raido Cop Cars etc.
We use to have crystal radios, no tubes just picking up the transmission of radio stations.
Circuits are much better shielded and designed today...
Not too hard to find a transmitter so turn them off...
Jul 23, 2012, 8:59 am
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Jul 23, 2012, 2:19 pm
#14
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Many planes now have wifi which means a good amount of people on the flight are on their laptops or phones in "non-airplane" mode. Is there a reason that the FAA believes that's safe, but on planes that don't have that ability it's not safe? Do the planes that are equipped with that have different navigational equipment or something like that?
Jul 29, 2012, 9:48 am
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Aircraft go through all sorts of RF interference testing before they are airworthy. The reason phones must be turned off is because it's virtually impossible for the FAA (or other governing body) to test every single device to make sure it doesn't cause issues.
Since some carriers now allow mobile phones and wifi in flight, I think it's pretty obvious they aren't a risk.
The main reason to have PED's turned off on takeoff/landing is to keep pax focused and ready in case of emergency.
I'd be willing to bet that in the OP's scenario, whatever the pax was using wasn't a mobile phone. They could have easily brought a VHF transmitter on board.
The majority of those issues are pax behavior issues. Actually, very few, perhaps none have anything to do with phones causing issues.
That being said, I found this one most interesting:
Synopsis
A passenger's Kindle Reader was crushed when a First Class Sleeper seat was
retracted causing a fire and smoke. A Flight Attendant put the fire out while the
flight crew accomplished the Smoke and Fire Checklist, including declaring an
emergency.
Since some carriers now allow mobile phones and wifi in flight, I think it's pretty obvious they aren't a risk.
The main reason to have PED's turned off on takeoff/landing is to keep pax focused and ready in case of emergency.
I'd be willing to bet that in the OP's scenario, whatever the pax was using wasn't a mobile phone. They could have easily brought a VHF transmitter on board.
That being said, I found this one most interesting:
Synopsis
A passenger's Kindle Reader was crushed when a First Class Sleeper seat was
retracted causing a fire and smoke. A Flight Attendant put the fire out while the
flight crew accomplished the Smoke and Fire Checklist, including declaring an
emergency.