De-ice

[Smokeyboy]

Opinions, clarification?
I'm not a pilot. Working in Airport maintenance and observed while removing snow, aircraft taxiing for T/O with snow on the fuselage. Never in my 39 years at the airport seen this. Every other aircraft de-iced completely this day. Spoke to the de-ice crew a couple of days after and asked them. Happened to be the same crew that de-iced this very aircraft. They asked the cockpit crew twice if they were sure that they didn't want the snow removed from the fuselage. Negative, wings and stabilizer only. They were suprised as well but, pilots decision. If it isn't necessary, airlines could save a lot of money and would benefit the environment.

[sonicbum]

Originally Posted by Smokeyboy

Opinions, clarification?
I'm not a pilot. Working in Airport maintenance and observed while removing snow, aircraft taxiing for T/O with snow on the fuselage. Never in my 39 years at the airport seen this. Every other aircraft de-iced completely this day. Spoke to the de-ice crew a couple of days after and asked them. Happened to be the same crew that de-iced this very aircraft. They asked the cockpit crew twice if they were sure that they didn't want the snow removed from the fuselage. Negative, wings and stabilizer only. They were suprised as well but, pilots decision. If it isn't necessary, airlines could save a lot of money and would benefit the environment.

"The Flight Crew Operating Manual allows takeoff with a certain amount of frost on certain parts of the aircraft (a frost layer less than 3mm (1/8 inch) on the underside of the wings, in the area of fuel tanks and a thin layer of rime or a light coating of powdery (loose) snow on the upper surface of the fuselage." (Airbus GTG with cold weather operations).

To me, the above does not look like a light coating of powdery snow or thin hoarfrost. I would have definitely asked for fuselage de-icing.
edit - disclaimer: It is obviously difficult to judge from a picture taken from distance probably with a mobile phone.

[awair]

Our definition of ‘thin layer’ was qualified to say that this meant the markings on the fuselage were still visible.

Although the OP has provided a low quality image, it would appear that text on the rear fuselage is still visible.

[+TSRA]

Our definition of ‘thin layer’ was qualified to say that this meant the markings on the fuselage were still visible.

This is the same at my current operator and every operator I've worked for; if you can still read the text, you're good. A low res image under overcast skies on top of a three-tone livery makes it look much worse than it likely is. I could get onboard with the idea that it might be a light coating of powdery snow, but I'll not judge the crew unfairly.

[sonicbum]

I have checked on the latest revision of the FCOM NOR-SUP-ADVWXR-GROUND OPERATIONS IN COLD WEATHER CONDITIONS and it does only mention the possibility of having a thin layer of hoarfrost. The GTG mentions some powdery snow as well though. In our Company's Cold Wx Ops manual (EASA Operator, not Wizz) we do mention thin hoarfrost as being acceptable on the upper side of the fuselage, no mentioning of powdery snow. I probably think that the above scenario (again we did not observe what the crew did) is a bit on the edge. To be honest, from a human factor point of view, if the ground staff asks me twice if I am sure I am not going to de-ice the fuselage and I also see everyone around me going for a complete de-icing, then I might start asking myself whether I am the smartest guy in the room (or on the apron in this case) or there is maybe something else I am missing.

[PENKO]

Although I agree that it is hard to tell wether this meets the definition of thin hoar frost, the OP specifically mentions snow. The fact that the cargo door is to be covered with frozen deposit seems to confirm this. I can only say that the operators I know would not condone departing with snow on the fuselage, regardless of cost saving.

[albatross]

Hoar frost and rime ice is much more of an impediment to lift ( think sandpaper ) and flight than clear ice ( think clear tape ) or snow that is not adhering to the airframe.

Canadian CARS

• 602.11 (1) In this section, critical surfaces means the wings, control surfaces, rotors, propellers, horizontal stabilizers, vertical stabilizers or any other stabilizing surfaces of an aircraft, as well as any other surfaces identified as critical surfaces in the aircraft flight manual.
  
• (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.
  
• (3) Despite subsection (2), a person may conduct a take-off in an aircraft that has frost caused by cold-soaked fuel adhering to the underside or upper side, or both, of its wings if the take-off is conducted in accordance with the aircraft manufacturer’s instructions for take-off under those conditions.
  
  JOKE
  MUCH more confusing Bafflegab Follows.
  Joke Over
  

[PENKO]

Sure, but we are not talking of the lift creation of the wing but wether snow (or ice, or other frozen deposits other than thin hoar frost) is allowed on top of the fuselage. It’s not on this type. That’s a different proposition.

[FlightDetent]

Well spotted. Critical surfaces.

Has anyone heard of 'representative' surfaces recently? Came across my CBT screen the other day, not sure what they meant (poorly translated).

[InSoMnIaC]

Originally Posted by FlightDetent

Well spotted. Critical surfaces.

Has anyone heard of 'representative' surfaces recently? Came across my CBT screen the other day, not sure what they meant (poorly translated).

our ops manual says the following:

Aircraft representative surfaces are those pre-approved surfaces which can be readily and clearly observed by flight crew during day and night operations, and which are suitable for making a reasonable judgment regarding whether or not frozen contaminants are adhering to other aircraft critical surfaces. Examination of one or more representative aircraft surfaces may be used for the Pre-Takeoff Contamination Check; if a tactile examination is not required. When identifying a representative surface the following guidelines are considered:

• The surface can be seen clearly to determine whether or not frozen contaminants are forming or accumulating on the surface.
• The surface should be unheated.
• During the deicing/anti-icing procedure, the representative surface should be one of the first surfaces treated with deicing/anti-icing fluid

[A320 Glider]

Critical surfaces are clear of any contamination.

[TheEdge]

Wizzair....

[shared reality]

Originally Posted by FlightDetent

Well spotted. Critical surfaces.

Has anyone heard of 'representative' surfaces recently? Came across my CBT screen the other day, not sure what they meant (poorly translated).

In my outfit (Northern Europe), we normally deice numerous times a day during the dark season. We have a "pretakeoff check" to be performed within 2 min of starting takeoff roll. Said check may be performed in 3 ways: 1. Mental review 2. Check of representative surface, and 3. Check of wings.
Our representative surface is determined in our FCOM (A320) as the left wing root area (so 2 and 3 are basically the same)

Now, for all practical purposes, I will only make a mental review (HOT still valid / no adverse change in met conditions since deice / not behind another aircraft too close as to get jet blast blow my fluids off etc etc). Should I for some reason be so unsure wrt my protection as to consider moving out in the cabin and politely ask a passenger to move over so I could check the wing (bad psychology...), then I would simply taxi in for another spraying session.

Rgds,