Originally Posted by ICE_BORE
It would be appreciated if you could let us know where, in your regulations, it allows you to take-off with snow/slush present on top of an applied film of anti-icing fluid...
In a non-regulatory document called
TP 10643 - When in Doubt... - Transport Canada
in paragraph 77
Frost, ice or snow on top of deicing or anti-icing fluids must be considered as adhering to the aircraft and take-off must not be attempted.
My company MANOPS also says:
Aircraft surfaces treated with de/anti-icing fluid should appear glossy, smooth and wet, if not, the fluid is no longer effective.
Some indications of loss of fluid effectiveness are:
- Progressive surface freezing (loss of wetness);
- Random accumulation, i.e. snow flakes remain on the fluid surface without melting;
- Snow accumulation;
- Dulling of surface reflectiveness (loss of gloss);
- Foggy fluid appearance (gradual deterioration of the fluid to slush); or
- Ice pellets precipitation is susceptible to degrade the de/anti-icing fluid very rapidly. It is believed that ice pellets are capable of penetrating the fluid and have enough momentum to contact the aircraft’s surface beneath the fluid. A local dilution of the fluid by the ice pellet would result in the vey rapid failure of the fluid.
If the de/anti-icing fluid exhibits one of more of the preceding indications, the aircraft must be considered contaminated.
But the law in Canada is the Canadian Aviation Regulations, part 602.11
Part VI - General Operating and Flight Rules - Transport Canada
(2) No person shall conduct or attempt to conduct a take-off in an aircraft that has frost, ice or snow adhering to any of its critical surfaces.
(4) Where conditions are such that frost, ice or snow may reasonably be expected to adhere to the aircraft, no person shall conduct or attempt to conduct a take-off in an aircraft unless
(a) for aircraft that are not operated under Subpart 5 of Part VII (meaning commercial non-airline),
(i) the aircraft has been inspected immediately prior to take-off to determine whether any frost, ice or snow is adhering to any of its critical surfaces, or
(ii) the operator has established an aircraft inspection program in accordance with the Operating and Flight Rules Standards, and the dispatch and take-off of the aircraft are in accordance with that program; and
(b) for aircraft that are operated under Subpart 5 of Part VII (airliners), the operator has established an aircraft inspection program in accordance with the Operating and Flight Rules Standards, and the dispatch and take-off of the aircraft are in accordance with that program.
(5) The inspection referred to in subparagraph (4)(a)(i) shall be performed by
(a) the pilot-in-command;
(b) a flight crew member of the aircraft who is designated by the pilot-in-command; or
(c) a person, other than a person referred to in paragraph (a) or (b), who
(i) is designated by the operator of the aircraft, and
(ii) has successfully completed an aircraft surface contamination training program pursuant to Subpart 4 or Part VII.
(6) Where, before commencing take-off, a crew member of an aircraft observes that there is frost, ice or snow adhering to the wings of the aircraft, the crew member shall immediately report that observation to the pilot-in-command, and the pilot-in-command or a flight crew member designated by the pilot-in-command shall inspect the wings of the aircraft before take-off.
Notice that the word "adhere" is always there, when the law could have been written with the exact same wording but with the word "present" instead of "adhere". Why ?