iPhone blamed for flight malfunction

[VH-Cheer Up]

from The Australian, 16 May 2013 (http://www.theaustralian.com.au/australian-it/iphone-blamed-for-flight-malfunction/story-e6frgakx-1226644142011)

A passenger using an iPhone mid-flight allegedly caused a compass malfunction on a US plane that sent it several kilometres off course.

Business site Bloomberg reports that the compass came good at the same time a flight attendant asked the passenger in row 9 to switch off their smartphone.

Bloomberg reports that despite recent calls for rules to be relaxed surrounding switching off phone functionality in-flight, airlines have logged dozens of cases where passenger electronics were believed to have interfered with navigation systems.

The incident is understood to have taken place in 2011.

The website AppleInsider said that modern wireless interference is believed to be associated with cellular radios in phones.

"That's why airlines that use the iPad as an electronic flight bag do not use cellular-capable versions of Apple's touchscreen tablet," AppleInsider said.

Wonder why this has taken two years to be published?

Anyone know any specifics about the case?

[Admiral346]

Looks like they had to sell all of their overpriced gadgets first.

[DaveReidUK]

Anyone know any specifics about the case? Aircraft involved was a CRJ2, unidentified US carrier, May 2011.

"After departing, climbing through 9,000 FT we 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, magnetic 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 cell phones left on may contribute to the heading problems. I made a PA asking our passengers to check their cell phones and make sure that they are off. Short of flying with both headings in DG we attempted to slew the compasses together again, and the EFIS COMP MON was cleared with no further messages. Our Flight Attendant called and asked if that had helped, I said yes, what did you do? He stated he walked through the cabin and spoke to each of the 12 passengers. A passenger in Row 9 had an iPhone in the standby mode, not airplane mode or off. He showed the passenger how to turn the phone off fully. The flight continued to destination with no further problems.

In my opinion and past experience the cell phone being on and trying to reconnect to towers on the ground, along with the location of row 9 to the instrumentation in the wing caused our heading to wander. The timing of the cell phone being turned off coincided with the moment where our heading problem was solved. Eight other flights in the same aircraft in two days span completed without a similar event."

[syseng68k]

This isn't very scientific, is it ?. I find it hard to believe that a
phone in standby mode could affect what is after all a magnetic sensor.
Avionics kit is stringently tested for rf susceptability and sensitive
signal cables are screened. The only way that there could possibly be an
effect is via rf into one of the antennas, but a phone on standby and
not transmitting ?. Convenient to blame the device, when it could be for
any number of other reasons.

A bit more scientific study might not be such a bad idea, with various
phones and devices, under all operating conditions...

[tumtiddle]

Well actually a phone in standby is still on and has it's aerials active. Standby in an iPhone sense is the same as "locked". Airplane mode disables the antenna and turning if off obviously means nothing happens, but a phone in standby is still turned on with an active cellular connection (or at least hunting for one at that height).

[Capn Bloggs]

find it hard to believe that a phone in standby mode
I don't have any rotten apples, but with Android (and I have no reason to think ios is any different), there's no such thing as "standby". All that happens is that the screen goes blank (either after time or by dating the power button). The device is still fully operational in all respects unless it is put into Flight Mode.

"My device comes on really quick from Standby" is a misnomer. All that is happening is that the screen is being turned on.

You've got to "slew the compass" in a CRJ? Ark version 2?

[Desert Dawg]

Agree with Tumtiddle.

From my knowledge of cellular comms, the phone is constantly in rf contact with towers, both sending and receiving data when the phone is locked, because there are two channels that the phone communicates on - one where you speak to your end party, and one where the 'background' comms work to connect calls, ensure tower linking, handshaking etc.....

Only when the phone is in Flight Mode, or Off, is when all communications are disabled i.e. no wifi, data, voice etc....

[Dave Gittins]

Have great difficulty believing the phone was the cause in an RF immune airliner.

The numbers of them that get left on either in pockets, hand luggage or hold luggage, this would be happening all the time.

[flyhardmo]

Well why don't they do a proper test and send up a CRJ with cell phones on only in row 9. They can repeatly switch the phone on and off and see if the problem is consistent. Sounds like a job for 'myth busters'

[EEngr]

Don't forget the potatos for the RFI test:

Boeing Potato Wi-Fi: Engineers Using Spuds To Improve In-Air Internet Signal Strength (http://www.huffingtonpost.com/2012/12/23/boeing-potato-wi-fi-engin_n_2355942.html)

[18-Wheeler]

Well why don't they do a proper test and send up a CRJ with cell phones on only in row 9. They can repeatly switch the phone on and off and see if the problem is consistent. Sounds like a job for 'myth busters'

Mythbusters did do that job and the results were interesting.
They found that on the aeroplanes they tried mobile phones on, they could not find any interference.
However, they also built their own simulated light aircraft cockpit with the usual array of instruments. At first they used regular unshielded wire and when they used a mobile phone near the instruments, they found a heck of a lot of interference going on. They then swapped all the wire over to the shielded type used in aircraft and found that the interference disappeared.

I've mentioned all this before several times here and it's been ignored every time. Hopefully this time someone will take notice and remember - My point being that unless you can guarantee that 100% of the wiring in 100% of the aircraft is 100% shielded, then there is a real chance of mobile phone interference.

[ShyTorque]

Yes, I flew a Sikorsky helicopter where the aft baggage bay smoke detector would be activated by any mobile phone left switched on, as it "polled" between cells during the flight. There was no fire extinguisher fitted in the aft baggage bay so the only safe response was to land asap and investigate. Not easy if you were IMC, or at night, especially over the sea. I used to explain to passengers the importance of switching off their phones, emphasising the exact reason for the requirement. They got the message (but obviously not by phone).

[compressor stall]

I've been in the front of an a320 family aircraft on a turnaround when the phone rang. The side window was open.

As it rang, GPS PRIMARY LOST flashed up on my ND and the ND slewed off to one side (was on 10mm range at the time). I finished the call and all went back to normal.

The other ND didn't change.

[Teldorserious]

It's already been proven that cars with Onstar can be hacked to slam the brakes, accelerate, and that the Airbus family has ground control over rides in case of hijacking or pilot incapacitation.

It's not new news that there is only so many frequency bands that electronics work on, that any phone can be hacked to transmit or a ground signal can transmit to an airliner the code necessary to screw things up on the deck.

It might have been what happened on 447.

The answer is simple, if you hire pilots that are competent, that you can trust, then you don't have to rely on gear that can be compromised so easily.

[gusting_45]

Ground control overrides in case of hijack ..........

Wtf are you talking about?

[bubbers44]

I have lost nav in a B727 twice when both units failed. I was able to continue but on a MIA to CUN flight had no long range Nav. When the passengers deplaned and baggage was unloaded everything worked perfectly again. It could have been an FM radio in baggage that turned on with an alarm or a cell phone.

I worked on business radio systems before flying full time and had some interesting situations, one when a weather receiver was jamming one of our companies radios in their office on a UHF frequency. I tuned to our frequency and drove the jeep around with a scope tuned to that frequency and it peaked out passing a business trailer. I stopped and verified their receiver was sending harmonics out of the antenna of their receive only unit and causing the problem. Also at KSNA we had a constant problem of clearance delivery having a loud squeal when they were reading clearances. I took a portable radio tuned to the frequency and it was our Aircal high speed printer in ops sending out the signal. We dealt with these interference problems a lot and they sometimes are not very straight forward solutions. Now with GPS and being familiar with your wet compass it shouldn't cause much of a problem if you can think outside the box a little.

[compressor stall]

13 years ago I had an old PC. Whenever I did insert column in excel, my clock radio used to buzz for a split second. Down the hall, three rooms away.

No other computer function was noted to cause the same effect.

[balsa model]

Well why don't they do a proper test and send up a CRJ with cell phones on only in row 9. They can repeatedly switch the phone on and off and see if the problem is consistent.
It's worth a try.
What's not a good idea is dismissing the possibility, outright.
Interference can be tricky to reproduce, sometimes. For example, the shielded wiring may have its shield grounding point(s) going intermittent. On the ground, all is fine; once in the air, with the wing bending up a bit, the wiring shifts and not so RF-proof anymore.
Once in the signal wires, RF can "mutate" through a variety of mechanisms down to the interference frequency. Even somewhat oxidized connectors are known to make a poor rectifier. Show me a schematic and we can start hunting for potential mixing hazards.
Anyhow, the sporadic nature of the reports of this sort, that I've come through over the years, makes me think that the problem could involve aircraft maintenance state/assembly quality, not just the design.

[akaSylvia]

The United Kingdom CAA in October 2002 conducted a series of laboratory tests which exposed general aviation avionic equipment to simulated cellphone transmissions. A VHF radio, a VOR/ILS receiver with HSI and secondary indicators, and a remote gyro compass system were used. At high signal levels, similar to that attainable from a cellphone 30 cm from the equipment or its wiring, anomalies were produced on all equipment readings except the glide slope indication. These tests confirmed onboard cellphones as an interference source, and endorsed current legislation restricting their use on aircraft.
The bolding is mine: cell phones can cause an issue in the cockpit. I've never seen any confirmation of issues from a distance, let alone the 9th row.

Unfortunately, I don't have the UK CAA report. That reference is from this 2011 NZ accident report:

Piper PA 31-350 Navajo Chieftain ZK-NCA, controlled flight into terrain, near Christchurch Aerodrome, 6 June 2003*
Aviation Reports - Aviation Reports (http://www.taic.org.nz/AviationReports/tabid/78/ctl/Detail/mid/482/InvNumber/2003-004/Page/4/Default.aspx?SkinSrc=%5BG%5Dskins%2FtaicAviation%2Fskin_avia tion)

Although I still think it likely that the crash was nothing to do with anomalies and everything to do with the fact that the pilot was using the phone on approach.

* No points for guessing why I'm looking at this crash ;)

[bubbers44]

The aircraft antenna is of course unshielded as the compass sensors so they would be the most vulnerable entry points of RF interference.

[Agaricus bisporus]

Its hard to believe that anyone who has flown a plane much has not heard the interference of a cellphone handshake (repeated creaking sound) over the RT or intercom.
It is equally hard to believe that anyone with enough technical knowledge to fly an aeroplane cannot understand that if the RF from a phone can induce a signal like that in a comms system it can do the same in any other electronic system - eg a control system.

As said above, there need to be too many 100% protection levels in too many different aspects of systems to assume immunity, and we cannot possibly predict how a signal from a mobile device in an infinite number of positions and orientations might be reflected and concentrated by structures and fittings into a vulnerable spot.

[DX Wombat]

I find it hard to believe that a
phone in standby mode could affect what is after all a magnetic sensor.
Avionics kit is stringently tested for rf susceptibilitySo is medical equipment but it happens, and one potentially extremely serious malfunction was witnessed first hand by one of our very experienced technicians.

[flight_mode]

Hello I’m new here!

I wouldn’t normally venture into Tech Log because I bimble around in a rented 152. My day job in designing and deploying mobile networks, including a couple of onboard cells used in many wide bodies.

Mobile phones adjust their transmission power dynamically depending on how far away they are from the nearest base station(s). At an airport their power will be very low because there’s several BS’s in the terminal. As they get further away the need to up the power.

Smart phones especially are in continuous communication with the network even when they are not being used. Push email, weather apps, facebook, Tw!tter and the like exchange data on an almost continuous basis.

A Smart phone is trying to keep two radio streams open, one for the voice and sms service and another for data. A mobile onboard an aircraft quickly gets confused. It finds itself moving too fast to be a able to locate and handover to another base station successfully and gets into a panic. As the distance between phone and ground increases so will the transmission power. It’s also struggling with the data connection. In normal operation the phone will use the fastest data service available which is normally HSPA or 4G, as the signal degrades it will fall back onto slower technologies with better reach; UMTS, then EDGE, then GPRS. In the air this signal degradation happens a lot faster due to the vs and forward speed. This also stresses the phone as it hurriedly tries to switch to slower technologies. Bursting data, renegotiating, bursting data again etc.

Once out of range of the base stations it will periodically search for a connection, sometimes at maximum power. Also, don’t forget the communications that might be going on with the PAX’s other technology. Bluetooth headsets, tethering and portable WiFi hotspots could all be exchanging information with each other.

The point on the previous page about airlines being RF immune is not correct. For starters they use RF to communicate! Although everything should be shielded perfectly that changes with age and maintenance interventions. Degraded insulation, temperature changes, stretch and flex will all open an aircraft up to potential interference. I know of a case, unfortunately not documented or scientifically proven in which a mobile was firmly blamed for slowing down the clock speed of a FADEC on a Williams FJ44 by a few MHz. Having a base station onboard will actually significantly reduce the chances of interference as the transmission power needed to communicate a few metres is very small. There’s also no cellular handover on onboard systems meaning phones don’t search around for other base stations.

[barit1]

flight_mode:I know of a case, unfortunately not documented or scientifically proven in which a mobile was firmly blamed for slowing down the clock speed of a FADEC on a Williams FJ44 by a few MHz.

Assuming this is true (as you say, not documented...), there seems to be a very low level of EMI protection on said FADEC. How could it survive a lightning strike - or (in a military world) a nuclear EMP?

[Flash2001]

Just as a oh-by-the-way. Screening a cable does not protect much against some types of interference. Electrical energy is carried by fields with a voltage component and a magnetic field component. Screening doesn't protect much against the magnetic component and, depending on the local impedance of space, the magnetic component can carry a lot of the energy.

With most information these days being moved in the digital domain, it is easy to produce a signal that has never been produced before. This makes testing very difficult.

After an excellent landing...

[bubbers44]

Probably the next step since some passengers don't shut off their cell phones is a flight attendant to walk down the aisle with a signal detector to catch the ones that don't comply with regulations.

[bubbers44]

As a pilot of a B757 I was amused by my cell phone going off at 3,000 ft on approach because I forgot to turn my captain cellphone off. It never caused a problem. It just said I missed a message. I didn't mean to do it, just forgot. I always stayed in tune with my wet compass so never let my heading change due to RF interference. With satellite nav with a minimal skill on using the wet compass no airliner should ever have a navigation problem. I practiced it all the time in my 757 heading south out of MIA.

We still have the magenta line followers that might have a problem. Not much we can do with them, I guess. I did the whiskey compass because I started in an Aeronca Champ and that is all I had. The B757 compass works the same way. The basics will always get you through, the Magenta line may if it is programed properly.

[MD83FO]

I once read that the true reason mobiles are banned, is due to the mobile carriers overload when the phones are in flight and and have tooo many antennas in line of sight.

[bubbers44]

My career missed that part. What airline cares if Verizon has overloaded cell stations on the ground? I know AA didn't.

[18-Wheeler]

It's also fiction. A mobile phone only access one tower at a time no matter how high they are.

[MD83FO]

Not the airlines but the FCC slash government slash FAA

[soylentgreen]

Note that some systems can make use of more than one base station simultaneously:

"Since adjacent cells use the same frequencies, CDMA systems have the ability to perform soft hand offs. Soft hand offs allow the mobile telephone to communicate simultaneously with two or more cells. The best signal quality is selected until the hand off is complete."

Source: https://en.wikipedia.org/wiki/Code_division_multiple_access

[18-Wheeler]

Ah yes sorry, soylentgreen, that's pretty much for the hand-over between the cells. So yes a mobile phone will talk to two towers at once, but it's really only working with one at a time.

[dkz]

I cannot comment on the CRJ issue since i'm not familiar with the type but i had my phone accidentally on throughout the flight at least 5 times in the last 10 years (A320/A330/A340) without any nav problem and also in my current outfit we have gsm/3g data/wifi enabled above 20.000ft and no fault was ever spotted. (Long haul, widebody operation, A330/A340)

[kilomikedelta]

One should be aware that poor electrical interconnections have non-linear properties that can result in the production of anomalous sum and difference frequencies that are usually quite unpredictable.