Does electronic equipment actually interfere with aircraft systems?

[scanman24]

Hi all,

I was recently reminded by a safety video that "electronic devices fitted with a transmitting function may not be used unless in flight mode, and must be switched of for take-off and landing" (or something to that effect). This got me thinking - why? It seems plenty of people use their electronic devices at all stages of flight, and with some airlines introducing wi-fi onboard I'm wondering to what extent - if any - safety is compromised through their use.

I'm not trying to endorse their use in complete disregard of air law, but I'm intrigued nonetheless.

Cheers.

[WhyByFlier]

In 'flight mode' I'd be extremely surprised if it has any effect. In my airline we're even flying with iPads cradled into the flightdeck with plates and manuals on the ipad.

Devices would need to be handed in if there was a real threat.

All this talk of electromagnetic interference! The plane can take a lightning strike for crying out loud.

[ShyTorque]

Some do, some don't. Rather than hold up the flight try to identify which are which on a passenger flight (and sort out the ensuing arguments from disgruntled pax), a blanket ban does the job.

For one example of interference caused by an electronic device, I used to fly a helicopter type where a live mobile phone being "polled" in flight would bring on the aft baggage bay smoke warning. Because there was no fire extinguisher in that bay, the warning coming on in flight meant an immediate landing. Not easy or safe over hostile terrain, in bad weather, or at night.

The anomaly was that the manufacturers said it shouldn't / didn't happen. That was probably because they hadn't carried out trials using the European phone frequencies, only those used in USA. Descending towards the sea at night, thinking the aircraft tail is going on fire, is no time to find these things out.

[Brian Abraham]

ShyTorque, one of our guys had exactly the same thing happen in Australia (S-76).

[FlyingStone]

One of the reasons for the restrictions on use of electronic devices during take-off and landing is that they could start flying all around the cabin during abnormal manuevers (such as rejected takeoff). And I don't think anybody wants to be hit in the head by an iPad, weighing more than 500g doing couple of m/s.

[QJB]

There is a pretty good Boeing article on this in their Aero magazine.

Aero 10 - Interference from Electronic Devices

[Bergerie1]

There have also been cases where electronic devices (mobile phones, etc.) have caused under-floor freight bay fire warnings on B747s - not proven but highly probable. As with the helicopter example in a previous post, a fire warning at a critical phase of flight or when way out over the ocean is not pleasant and is a significant cause for concern.

[roulishollandais]

And what with Lithium batteries overheating of these devices...?

[ShyTorque]

ShyTorque, one of our guys had exactly the same thing happen in Australia (S-76).

Yes, same type.

[compressor stall]

I've had the phone ring on a turnaround (A320 family) and simultaneously watched "GPS primary lost" appear, and the airport and SID slew over to the side of the ND. (20 mile arc IIRC).

All came good once I answered!

[bubbers44]

I have been guilty of as a captain leaving my cellphone on and it going off at 3,000 ft on approach telling me I had a missed call. I don't know if cell phones cause any interference but have had a couple of flights when all long range navigation failed in a Boeing 727 but worked when all passengers and baggage was removed at destination. Something in checked bags or carry on must have caused it.

[pukua]

If it can't be certain NOT to interfere with the flight it will be banned as no organisation will stick their neck out to say it is safe in ALL circumstances! Certain electronic devices that are tested for flight deck use only or other restricted use will be approved as testing and liability is established.

[scanman24]

Thanks everyone for the input - question more than answered!

[John Farley]

Does electronic equipment actually interfere with aircraft systems?

I think that might rather depend on the (portable?) electronic equipement concerned and the aircraft it was being used in as well as its position in the aircraft. I really can't imagine an question that is likely to have more variables.

As has been suggested testing a specific bit of kit under specific circumstances in the aircraft might allow clearance of that kit - but a blanket 'go ahead' seems unlikely.

[fizz57]

I remember reading an article in some journal or other a few years ago about a researcher who carried a spectrum analyser in his tote bag on a number of flights to record cellphone activity (probably with authorization - he was quite an anti-electronic-devices activist).

His results showed a surprising amount of activity on each and every flight. Of course, he interpreted this as being indicative of the magnitude of the problem. But if that is the case, why aren't planes falling out of the sky like flies?

[darkroomsource]

Not like flies, but there have been a few cases where planes ended up hundreds of feet away from the end of runway, and if the weather had been worse they might have been hitting buildings.
We've been lucky so far.

[WhyByFlier]

From Airbus A320 FCOM FCB-FCB8 P 1/2

‐ Airlines often wonder whether they should allow passengers to operate electronic devices in the cabin without any limit. Federal Aviation Regulation (FAR) section 91.19 allows passengers to operate: • Portable voice recorders • Hearing aids • Heart pacemakers • Electric shavers • Any other portable electronic device that the operator of the aircraft has determined will not cause interference with the navigation or communication system of the aircraft on which it is to be used. It is obvious that the myriad portable devices that now exists or that may be available in the future cannot be tested. ‐ As far as aircraft specific electrical flight controls and engine control computers on Airbus aircraft are concerned, there is no chance of their operation being affected by passenger-operated electronic devices, due to the high level of protection applied to these systems. ‐ Nevertheless, this question arises for navigation and communication receivers and is applicable to any aircraft. A study has been conducted by an RTCA (Radio Technical Commission for Aeronautics) special commitee. ‐ The conclusion is that the probability of a passenger-operated device interfering with the ILS localizer during a typical flight is about one in a million. Airbus Industrie recommendations is that no portable device should be used during take-off and landing. ‐ Concerning radio phones Airbus Industrie recommends to prohibit the use of those devices.

[NSEU]

and with some airlines introducing wi-fi onboard I'm wondering to what extent - if any - safety is compromised through their use.

Standard tests are carried out to try to ensure that they don't affect aircraft systems, but like any electronic devices, they can develop faults which are unexpected. Even thoroughly tested Inflight Entertainment Systems (on and off-wing) have interfered with airplane systems. Even though, in many cases, the system problems are only minor, they may cause distractions at critical times.

[grounded27]

99.99%, hell no. .01% mabe. Liability 100% for .01%.

[Uplinker]

Airbus, and probably all modern aircraft, use heavily screened cables to reduce interference from external sources, but that is not a 100% guarantee. As others have said, you don't want to find out at the DH that your CatIIIB autoland is 50m off laterally. At best; a go-around and a delay, at worst...........

I remember a study in the ?80's that showed radar tracks of aircraft - and one was flying an airway in a series of 'sawtooth' steps instead of a straight line. Radio interference from a laptop, I think, was the culprit.