Originally Posted by
Denti
Boeing 737NG. Widely available in the FCOM, however, separate approval by the relevant authority is needed.
Takeoff with light coatings of cold-soaked fuel frost on upper wing surfaces is allowable, provided
the following conditions are met:
• the frost on the upper surface is less than 1/16 inch (1.5 mm) in thickness
• the extent of the frost is similar on both wings
• the frost is on or between the black lines defining the allowable cold-soaked fuel frost area (see figure) with no ice or frost on the leading edges or control surfaces
• the ambient air temperature is above freezing (0°C, 32°F)
• there is no precipitation or visible moisture (rain, snow, drizzle or fog with less than 1 mile visibility, etc.)
I remember having this discussion with a South European airline captain, he insisted de-icing was not necessary. We deiced anyway, pointing out the the UKCAA had not approved the procedure. This was well over 20 years ago so I've no idea if it was subsequently approved by EASA.