Cautionary tale posted for the benefit of anyone else who, like me, knows what you're supposed to do then does something different when distracted... Even if you're visiting relatives who live 100 miles away from your last flight location who are very keen to see your new toy; even if the wind-chill is bitter and you're feeling it because you forgot your gloves and hat; even if the take-off point proposed is over there right in the freezy breeze, but it's sheltered here... DON'T recalibrate your compass somewhere you should know better just to get out of the chill wind and let the rellies see and hear you talk through what you are doing. Take-off was great, hovering steady and auto-correcting for the wind at 100ft up. Eyes to the app to line up a nice shot. All of a sudden full forward, apparently uncommanded. First thought was "uh oh, fly away!" I think I had actually hit the stick forward with my coat while cupping the phone to shield from a bit of glare - in any event when I spun round to look at her she stopped, and I could bring her back overhead. Then I noticed the LEDs were not their usual happy green, and a glance at the app showed zero satellites locked, and the Vision bucking around a bit. During a quick descent the LEDs started to flash alternate colours and the app screen said "Compass Callibration required". I managed to bring her close enough to grab her out of the air and kill the props - but I had to actively fly her in the breeze, and nose in, to get her home - and there were tendencies to veer and buck as she got and then lost GPS lock and tried to fight the screwed compass. I was very glad for the year I've had flying micro quads and the nose-in muscle memory they've given me... I recalibrated again on the nice, clear part of the field I was now in and had an uneventful further flight (until my fingers went numb). Coming back to the car I critically appraised where I had done the initial calibration - 6 feet from the car, 10 feet from a large metal gate, 3 feet from a metal fence post. Stupid. Don't skimp on your pre-flight routine ever, and be especially cautious of double-checking yourself if you have interested people around asking you questions and wanting you to show them what you are doing - or if you've forgotten your hat.