According to CAA PAPER 2003/3 “Effects of Interference from Cellular Telephones on Aircraft Avionic Equipment” the problems caused by a mobile phone 30 cm from an avionics and instrument panel are:
- Compass froze or overshot actual magnetic bearing.
- Instability of indicators.
- Digital VOR navigation bearing display errors up to 5 degrees.
- VOR navigation To/From indicator reversal.
- VOR and ILS course deviation indicator errors with and without a failure flag.
- Reduced sensitivity of the ILS Localiser receiver.
- Background noise on audio outputs.
This was few years ago now so phone technology has moved on, even if most UK GA cockpits still date back 25 years or more.
When asking my question I had in mind some simple practical checks a pilot could make with just a mobile phone and observing its effects on the aircraft.
There are lots of adverts in the aviation magazines for headsets that have a capability for a Bluetooth connection to a mobile phone. I thought that maybe using one of these headsets or something similar, it would be possible to hold the phone in front of the avionics stack, or in various positions around the cockpit, while making and receiving a few test calls.
Observing the avionics behavior during the test calls might then give a rough indication of any potential interference problems?