On 2014-09-15 17:20:37 +0000, noel.wade said:

One interesting thing no one has mentioned on this thread is the
built-in barometer/pressure-sensor in the iPhone6. It raises some
interesting possibilities for IGC logging and possibly some kind of
certification by the IGC for badges/contests/records.

Yes, I've been waiting for that feature for years. Many Android phones
have had it for a while. Unfortunately I just this year upgraded from a
4 to 5s (skipping 4s and 5) so wasn't planning another purchase quite
yet...

Apple will no doubt have done their usual sterling job of simplifying
the programming interface so that you just ask for the height, and
they've already done the heavy lifting to calibrate the pressure
against a long term GPS height average (actually, you'd calibrate the
difference of them to be zero), and use the pressure for fast/fine
changes. And probably gone on from that to derive sea-level pressure
for the weather apps...

Hopefully the raw barometric pressure is available too.