Podge wrote:
I was on an Air New Zealand flight a while ago, and I started to take a
few pics (from my digital still camera) as the aircraft took off. An air
hostess politely told me that the use of electronic devices was not
permitted during take-offs or landings. I told her that I was using a
dedicated still digital camera and not a camcorder, but she still asked
me to turn it off. About 10 minutes later, when land was well out of
sight, we were able to turn on our "electronic devices". But about 10
minutes before landing, while still over the sea, all electronic devices
had to be turned off again. The only worthwhile photography from this
flight was during the first and last 5 minutes of the flight, and this
would apply to many other flights that I have been on.

Now I know that the use of camcorders has been banned during take-offs
and landings, but I didn't know that digital still cameras now suffered
this fate. My digital camera can't take movies, but I know that a lot of
digital still cameras can also take movies. From a practical point of
view, does anyone know whether digital cameras really CAN interfere with
an aircraft's navigation systems? Are airlines being a little too
cautious with regard to the use of digital cameras and camcorders?

About 5 years ago, nobody cared when I used my camcorder or digital
still camera during take-offs or landings, and there were no reports
then of interference with the aircrafts' navigation systems! So what has
changed during the last 5 years?

Any digital device can easily interfere with avionic systems.

They all contain square wave clock oscillators and logic circuits which produce
broadband radio noise which can easily land on critical frequencies for things
like precision approach, radar or communications systems.

Analogue radio equipment can also interfere unintentionally but this is much
less likely as the oscillators generate sine waves and thus only produce
signals on one frequency at a time. Purely analogue electronic devices are
getting pretty rare these days.