An iPad 2 unfortunately is no longer a good choice for Aerofly 2. With each new iOS version, iOS requires more memory, leaving less memory for Aerofly 2.
So if you fly for a certain distance, some airports are loaded as you approach then, but older ones are still kept in memory, to avoid a loading/unloading scenerio. However this causes the iPad 2 or iPad Mini 1 to run out of memory.
At least its good for us that those devices are no longer sold by Apple.
Thanks for the info. A bit strange that this only happens with SFO, but OK