A friend of mine was travelling from YYC to the UK a couple of months ago on a 767.
When I saw him again he had a question with regards frost on wings. He said that during pushback he noticed some frost on the upper surface of the wing which he brought to the attention of the CC. He was relieved to see that this was brought to the attention of the flight crew, as the FO came down to look at the wings. After a few minutes the CC member came to inform him that it was only frost, and that they could depart (which of course was uneventful).
This got me wondering, and next time I went to work I dug out my supplementary procedures for the 757. This is what it says.....
Surfaces ............................................................ ..............................Check
Takeoff with light coatings of frost, up to 1/8 inch (3mm) in
thickness on lower wing surfaces due to cold fuel is permissible;
however, all leading edge devices, all control surfaces, and upper
wing surfaces must be free of snow or ice.
Thin hoarfrost is acceptable on the upper surface of the fuselage
provided all vents and ports are clear. Thin hoarfrost is a uniform
white deposit of fine crystalline texture, which usually occurs on
exposed surfaces on a cold and cloudless night, and which is thin
enough to distinguish surface features underneath, such as paint
lines, markings or lettering.
There is one line in this statement that suggests all leading edge devices, all control surfaces, and upper wing surfaces must be free of snow or ice, with no mention of frost, but the bit before it suggests; takeoff with light coatings of frost, up to 1/8 inch (3mm) in thickness on lower wing surfaces due to cold fuel is permissible. From this statement alone I would infer that de-icing was required.
I personally believe in the clean wing concept and would de-ice every time.
Would anyone else have departed without de-icing?