Originally Posted by CAA Paper 2003/03
Observations and Conclusions
6.1 The tests revealed various adverse effects on the equipment performance from simulated cellphone interference. Although the equipment demonstrated a satisfactory margin above the original certification criteria for interference susceptibility, that margin was not sufficient to protect against potential cellphone interference under worst case conditions.
6.2 As recorded on the worksheets reproduced in Annex 1, the following anomalies were seen at interference levels above 30 volts/metre, a level that can be produced by a cellphone operating at maximum power and located 30cms from the victim equipment or its wiring harness.
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.
6.3 Most anomalies were observed at 1719MHz.
6.4 For the general case, and depending on the other aids available to the flight crew, the consequences of the observed anomalies could include crew distraction, confusion, and loss of confidence in the equipment. The degraded navigation precision could result in an inability to meet required navigation performance with potential adverse effects on aircraft separation and terrain clearance.
That was a study conducted perhaps 4 years ago which is a very long time in the development of wireless connectivity.
Mobiles and other wireless devices left switched on inadvertently has hopefully been a managed risk in aviation for some years now.
Ryanair's aircraft are all pretty much the same now and I guess that without exception, their fleet's manufacture might postdate the CAA report, and that a fleet such as theirs might be as close to an ideal "control" group in an experiment as any other fleet flying.
Many kinds of wireless devices get carried about the person in a typical aircraft thesedays - a couple of weeks ago I carried four such devices: 2 wireless capable Wiis, a bluetooth mobile and a WiFi / bluetooth mobile into the cabin. Only the latter was part active because it always is I think unless I remove the battery (which I didn't - should I have done? - it's a Nokia 9500.)
Other people will have carried laptops onboard with various types of Wireless connectivity - some will no doubt be part active throughout the flight whether used or not ... and hopefully not a problem.
If it IS a problem then it needs managing because as the OP has indicated, it isn't managed at the moment.
Edit: Actually a search of the CAA document repository for the word "cellular" shows that at least two fairly half-hearted attempts at describing the continuing problems dated November 2005 (CAP 756) and December 2006 (CAP 768) have been published and both put the responsibility on the shoulders of the airlines themselves.
We know what that means then. Plus ca change, plus cest la meme chose.
I think I'll just creep back under a light covering of straw and hope for the best again...Squeak Squeak
