That must have put the wind up both of you, sounds like the snow had compacted down to form that nasty almost black ice type surface in the wheel tracks.
I too would have expected the car to hold itself back via engine braking in those circumstances, especially with an AWD version.
Have had some peculiar experiences with electronics over the years, in my early years on transporters i drove some really worn out tackle with steeper lorry decks than you find now, and being aluminium had become polished to a lethal smoothness by thousands of wheels passing up and down them...had instances on icy decks where ABS equipped vehicles would be out of control and actually gathering speed with the brakes releasing by themselves whilst attempting to come down slowly whilst older cars without ABS had no such problems.
The common theme between my experiences and yours is really slow speed, i don't think the systems on these vehicles can cope with slow speeds and allow the brakes (maybe when in gear in your Audi) to release when they shouldn't if the system gets confused, which is probably what happened, but i too would be concerned that the engine would race away, unless it was the fact the tyres regained grip and your speed had increased to the equivalent of 3000 rpm.
Different system entirely to a proper Hill Descent Control as fitted to some too-complicated-by-half off road type 4x4's.
Hence the advice (if you have three hours to spare to read the handbook cover to cover) to switch off ASR/TC/ESP or whatever fancy name they give this trickery, the thing is when is the normal driver supposed to turn the system off.
Easy enough decision when normal TC cuts the power should it detect wheelspin when you're trying to climb a hill, different kettle of fish when its the opposite scenario and the car is careering off down a slippery slope aided and abetted it would appear by what sounds like a poor stability control system...i would have expected better froma quattro version, but no doubt the car is shod with elastic bands on huge wheels to make things much better..:-).
Well done for not panicking and bringing the drama to a safe ending, could have been somewhat different to that for any of us.
Edited by gordonbennet on 22/01/2015 at 18:47
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