Originally Posted by The Swinging Monkey
We are always told (as SLF) that we must switch off all electronic items in the cabin prior to take off and landing ie Phones, Laptops etc. And we all know that just prior to landing, all the numpties get their phones out and switch them back on!!
1. Is it possible that some kind of interference from a phone(s) could be the 'cause' ?
2. What aircraft systems DO mobile phones interfere with?
Interesting question, this one provided some entertainment as I browsed a non-professional aviation forum, which contained an amusing hypothesis: The UK PM was in the terminal at the time, therefore some mobile phone band jamming equipment favoured by his protective detail was in operation!
My understanding of the 777 FADEC for both engine types is a dual-channel Engine Electronic Control unit for each motor. To have the EECs shut down both motors simultaneously would (I imagine) require a malfunction of all four EEC control channels. I am only relying on my knowledge of FADEC function in BR715, a different engine from a different manufacturer, but with a similar EEC.
Control of the EEC requires, among other things, digital signalling from the throttles (linear variable differential transformers) that provide a throttle/thrust lever resolver angle to the EEC. Other inputs to the EEC for aircraft and engine configuration, pressure and temp sensing at various engine stages, etc, are also inputs to the EEC.
I'm not an aircraft engineer nor an electronics/RF specialist, but I would be surprised if RF interference from the sources you mentioned would be of any nuisance to autothrottle and FADEC operation.
RF interference is more likely to be a problem for those systems that use/sense RF transmissions. Comms, nav equipment, etc. Example: I regularly hear the 'beep-beep, beep-beep' of GSM phones logging into the nearest mobile phone tower on taxi in, despite instructions to remain switched off until inside the terminal! Also, GPS satellite signals are several factors
weaker than normal background radiation, certainly less than the gain of mobile phone Tx.
I'd be surprised if this were due to mobile phone Tx, or the PM's jammers!