Practice and Visual Illusions

 Finally got up after a two month gap and just did circuits last weekend.  Straight practice for an hour at Martensville.  A nice clear day with excellent visibility, warm enough to make starting simple, cold enough the ground was still hard.

On the very first touch and go I was presented with a powerful visual illusion.  I was landing on runway 26, and the snow was still covering the south edge of the runway.  But the north edge was clear of snow.  

I lined up dead center on the brown patch and was over the fence before I realized my mistake.  There was no drama and I went around without touching down.

But this is an excellent example of why practice in varying conditions is good for a pilot.  This sort of illusion almost certainly contributed to the Delta airlines accident in Toronto where the aircraft slammed into the runway without much evidence of a flare.