LFS
Yes, somebody wrote that guidance paper up for airlines. It isn't based on anything scientific that I can see. The usual CAA stuff.
JB
I can't believe you joined in Feb 2006 yet that name has been unreserved all that time!!!
Anyway, when did this happen and is this first-hand i.e. did you see that letter? The reality is that there are hills around Welshpool that are as high as a lot of people fly at, and I have not heard of a ban on hill walking while carrying a mobile phone.