Turning off Electronic Devices?

[Ziggy]

There is a potential for EMI to effect the aircraft's IFR under 10,000 feet, so fhey err on the side of caution.

Which is a good thing.

 

[gumbyk]

From a CNN report:
The risk is low
We can find no instance in which electromagnetic interference from a portable electronic device brought down a commercial plane or was a contributing factor in an accident. And the National Transportation Safety Board says it has never issued a recommendation about such devices on planes.
But those who flatly say there's no evidence that electronic devices have caused interference on planes are wrong.

However, I've seen first-hand what a cellphone can do when an aircraft is on autopilot.
I was watching an avionics engineer test a new autopilot installation in a light twin-engine aircraft (on the ground), when his phone rang in his pocket. Aircraft went to full nose-down as fast as it could. Certainly an eye-opening experience.

 

[GrauGeist]

However, I've seen first-hand what a cellphone can do when an aircraft is on autopilot.
I was watching an avionics engineer test a new autopilot installation in a light twin-engine aircraft (on the ground), when his phone rang in his pocket. Aircraft went to full nose-down as fast as it could. Certainly an eye-opening experience.

I'm sure that was a stressful moment!

I know that even an improperly crimped coax on a BNC connector on the back of a VHF radio can mess with the aircraft's instruments.

And EMI is not unique not just aircraft, but I had a fire engine that had a bad PL259 connector on the back of a Kenwood lowband that when keyed, would propegate into the electronic engine controls and rev the engine. Not good - especially when the fire truck was sitting at a stoplight and the engineer had to talk to dispatch.

 

[gumbyk]

I'm sure that was a stressful moment!

I know that even an improperly crimped coax on a BNC connector on the back of a VHF radio can mess with the aircraft's instruments.

And EMI is not unique not just aircraft, but I had a fire engine that had a bad PL259 connector on the back of a Kenwood lowband that when keyed, would propegate into the electronic engine controls and rev the engine. Not good - especially when the fire truck was sitting at a stoplight and the engineer had to talk to dispatch.

Yep, just lucky it was found on the ground!
If I remember rightly, the whole installation was removed and then re-installed, with attention to shielding, and the owner was very cautious for a long time afterwards.

 

[MiTasol]

I thought the Mythbusters proved the interference thingy as false..

Actually, about 10-15 years ago, the UKCAA proved it very real on certain aircraft and under certain conditions.

I no longer have the report but at the time it was a serious concern to my employer.

Around the same time there was also an EMB-110 crash in Fiji that was linked to passenger use of cell phones and an Airbus in Thailand that crashed in bad weather during its third landing attempt. On that it was known that many passengers were on their phones talking to friends to tell them they were running late. EMF from the phones was listed as a possible cause of control surface movements that did not reflect cockpit inputs.

 

[MiTasol]

gumbyk said: However, I've seen first-hand what a cellphone can do when an aircraft is on autopilot. I was watching an avionics engineer test a new autopilot installation in a light twin-engine aircraft (on the ground), when his phone rang in his pocket. Aircraft went to full nose-down as fast as it could. Certainly an eye-opening experience.

I have been in a light twin where when we keyed the mic for the HF the aircraft turned hard left and a gentle nose down. Fortunately we were climbing and at a fair altitude and the pilot immediately released the mic button. We leveled out and slowed down and did several more tests with the same result every time so that aborted our trip for week.

We took it to a different company from the one who had just done the HF installation for troubleshooting and they found that the HF harness and antenna lead were zip tied to the autopilot harness and that there was no shielding. A perfect example of human factors causing incidents and potential accidents.

 

[gumbyk]

Actually, about 10-15 years ago, the UKCAA proved it very real on certain aircraft and under certain conditions.

And that's the problem with it - you cannot always replicate a confirmed incident to 'prove' it was a cellphone, as there are so many variables in play that a test as simple as what Mythbusters did.

In the case I saw, as the test was being conducted on the ground, there was a ground station emulator being used, IIRC, the aircraft had just had a GPS installed as well. It may never have happened again as that particular set of parameters (including antenna distances) may never have been replicated.