Do I turn off my mobile when flying?
No. And never had any problems.
Wow, now that's an interesting air safety philosophy.
What an extraordinary thread! Professional pilots (I presume) discussing the merits of breaking safety regulations because they "know better". I'm amazed.
Petrol station "myth". If you've done a CPL you know that all electromagnetic transmissions can, and will, induce current in nearby metallic objects. Whether or not this creates a spark is immaterial, it's clearly negligent to do anything that adds to the risk.
We don't know how signals affect our aircraft, so why risk it.
I thought there was a fairly extensive body of evidence that mobiles do indeed affect airliner systems, and probably caused a crash in the Far East a few years ago. Read it here on PPRuNe a few days ago but can't find it right now. Edit - try this for size!
http://www.cmu.edu/PR/releases06/060228_cellphone.html
It is illegal to use any transmitting device above a certain level (30'?)above ground in the UK (tall buildings count as ground) unless licenced. This is an old Post Office regulation and carries stiff penalties. I had a pax threatened with a visit to court for using his phone in the air - he was got by exactly the method someone rubbished above - blocking out a number of ground relay stations and making the computer cough. So it does happen.
And as for turning antennae to point downwards...perhaps he was joking. If not better read up on electromagnetic propagation & polarization and see where you went wrong.
What's wrong with doing it like we should, Professionally, and leaving the damn things off in flight?