Lu
It's non-polluting as well. Can only improve the environment.

Whilst not in full agreement with L337's description of events that led to the accident to N90AG at EGBB last January, the AAIB final report will no doubt answer the key question posed at the start of this thread.

Please do read it carefully.

The first knowledge I have of accidents caused through a lack of de-icing goes back to the 1930's when a flight of military aircraft took-off from a field in Scotland. All came back to earth with a bump! It was a relatively new experience in those days to discover the effect of ice and frost on even basic aerofoils, let alone super critical wings.

Why is it we are even still asking the question - do we never learn!

Very third hand description it was. But reliable source! So I hope not too far from the truth.

L337

NASA did quite alot of research after the ATR turned over a few years ago as a result of icing. Some of the tests were done on an ATR and some on a Twin Otter: several papers were produced as a result. I don't know where you would get copies, but I saw them at Flight Safety Canada (Toronto): might be a starting point for you. There is also a pink AIC: check your AIP in your ops room, or where ever your company keeps it. In essence it says if in doubt, deice, and be very careful about hold over times, and if you're still in doubt, deice again. It is illegal to take off with contamination on the lift surfaces.

That said, and this was a special situation, in the Sahara in winter there is often a frost at night. The temperatures rise quite quickly as soon as the sun comes up and melts the frost off the wings almost instantaneously. Ground temperatures could be -2 or -3, but temperatures at 50' would be in the order of +10 or so, and there was no deicing on hand anyway. We were allowed by company rules to depart with frost on the wings, but not ice.

I see Airbus have just published a bulletin relating the dangers of contamination on A321 wing surfaces and referring to two incidents of near loss of control in flight caused by ice.

Procedure recommended...use F3 for landing and VLS + 10 minimum.

L337
Think you will read about the effect of APU exhaust and its role in the particular ambient conditions on that day; not the morning sunlight.

I think one of your other comments may have been speculative.
Enough said.