The short answer is, don’t do it! That’s not always possible though, as it can creep up on you.
Coming to the airfield the other day, one couldn’t see as far as the pylons. Everyone was huddled in the clubhouse waiting for the fog to lift, listening to the CFI telling us about how fantastic his flight was just an hour ago. The winter gloom was descending on all the pilots, itching to get up in the air.
‘That’s it, I can see the pylons, let’s go!’ The clubhouse emptied and I was left chatting to David, who got his licence some years ago.
‘I once found myself in fog,’ he told me. ‘I was 800 feet from the ground, just coming in to land. I hadn’t really noticed how bad the weather was, and suddenly I could see nothing. I tried to do a 180 degree turn, so I could head away from the airfield. Obviously, I didn’t manage it, because just as suddenly the fog lifted and I found myself heading straight at the pylons and at the ground! It taught me something, that’s for sure!’
‘First of all, to take more notice of what the weather is doing in these gloomy days, as that’s when the fog can come in fast. Also, to be aware of my compass heading, because if I had been, I could have done the turn properly. And also the altimeter, so I could have kept it a level turn.’
The most critical factor for fog is whether the dewpoint and the temperature are the same. If they are, beware! Cloud you can fly around, but fog can surround you suddenly, and totally disorientate you.
Time of day – if there is only one degree between dewpoint and temperature, don’t go flying late on a winter’s afternoon when the temperature will be dropping, as opposed to going out in the morning when it’s rising.
What can make the temperature drop – a large volume of water, like the tide coming in or out, sea mist, so if you are near a river or the sea, be extra careful.