Comments on: Bluetooth mouse may have caused plane to fall out of the sky

Qantas is investigating the possibility that a Bluetooth mouse, laptop, or video game use caused one of its planes to plunge, injuring at least 20 people.

[CmdrRickHunter]

The idea is truly preposterous. A plane would not be allowed to fly if it depended on martial law within the cabin full of civilians regarding all electronic devices. And certainly, if that was the case, there would not be a list of forbidden items. You simply woudlnt' be allowed to have any electronics on your person, and the cargo bin would be in a fariday cage.

There is, however, one posibility. I do know that, recently, studies have been done to see whether or not you could replace wires in a plane with wireless technologies. The specific technology they found worked best was bluetooth. They found they needed several relays placed along the fusliage because bluetooth's range was too short to reach end to end. Was this quanta equipped with this technology?

Bluetooth uses frequency hopping to avoid interference. If there is interference between two bluetooth devices, it is very unlikely that that interference will occur for long as the devices hop to different frequencies shortly afterward. I can, however, see plane designers disabling this technology in the name of determinacy (frequency hopping does yield some randomness that is hard to model). If they foolishly did so, a malfunctioning mouse could, in theory, get unlucky and lock onto the same frequency. it could begin generating enough interference to get in the way of a broken bluetooth implementation.

If so, the bluetooth industry should not be put at fault. They EXPLICITLY put frequency hopping into the spec to decrease the effect of interference. That frequency hopping is sufficient to keep people in a crowded new york city block full of bluetooth headsets from intefering with eachother. There is no explaination for bluetooth causing such interference unless the airline was using the technology and specifically broke it.

[ChrisMatyszczyk]

Cmdr,

Thank you. That is an excellent and informative explanation. You are very kind to offer it.

Chris

[ArtInvent]

It is pretty hard to believe that a radio signal, ANY radio signal, could interfere with the actual control mechanism of a plane. I would think that controls are all closed, hardwired networks, whether mechanical, electrical, optical fiber, whatever. And that any wiring would be shielded in a multiply redundant way from any possible EM interference.

Certainly other plane systems, such as the radio and other communications systems, use wireless and have since planes started flying. But using any kind of wireless system for actual control would be ludicrous, I don't care how 'secure' the system is made out to be.

[nintendoeats]

When you fly in an airplane, an untold number of signals on the radio-spectrum (both manmade and natural) will hit the plane. If these could throw off airplane systems, we would know.

[Get_Bent]

New airline regulation: No playing Flight Simulator while on board the plane.

[ChrisMatyszczyk]

Hah. Yes, that would be more dangerous that watching porn, no?

Chris

[pinm]

Can you imagine ... terrorist on a plane, "all of you will give me your money or I will turn on my cell phone"

It cant be that simple, that would make it too easy for someone to crash the plane.

[chris-johnson]

Kent Wein wrote an brief article about cell phone use on airplanes on Gadling.com in July, 2008. See http://www.gadling.com/2008/07/18/plane-answers-a-rant-in-favor-of-cell-phones-on-airplanes/ .

Wein cites a 2003 Carnegie Mellon University study that found problems with the use of cell phones in flight. Wein's article provides a link to the full report of the study and a link to an interview with Bill Strauss, the person responsible for the report.

The article does not address possible interference from other consumer electronic devices that can generate radio signals, such as laptops, wireless mice or bluetooth devices, nor does it address new technologies such as in flight WI-FI.

Although Wein's article is specific to cell phones, based on the conclusions of the Carnegie Mellon study, it is reasonable to be concerned that other radio frequency generating consumer electronics devices could interfere with airplane avionics as well.

[zerohourrct]

A few facts followed by a conslusion;
All electronic devices, wireless or not, emit some magnitude of interference. That's what that FCC label you read on nearly every electronics device in the US is trying to tell you.
All electrical conductors (read wires/antennas) pick up this interference in varying degrees, depending on how well shielded they are, and the magnitude of the interference.
Wireless devices create A LOT of interference for other devices (they often must be powerful enough to send signals for miles, and then some)
Most of the field of electrical engineering is devoted to ways to minimize and prevent this interference from effecting other circuits, or shielding said circuits from outside interference.
What likely happend is that by some stroke of dumb luck, either the plane's electronics malfunctioned independantly of outside interference, or some outside interference managed to screw up the plane's electronics for a brief period of time. This was most likely allowed to happen by recent repairs/modification and incosistancy in the shielding of the wires on the plane.
The strength of interference required to do this would still probably be far beyond the power of conventional hand-held electronics, although it is possibly. The possibility skyrockets if one of these wireless devices was very close (right on the other side of a thin plastic interior wall) to an unshielded wire, which was likely the case here.
Personally, I will follow the attendants instructions and turn off my wireless devices during flight. Even if the chances are one in a billion, I haven't been very lucky recently. I wouldn't want THAT to be my 'lucky' day.