Reply to post #491;
Jaxon;
JO is spot on and I support the views expressed without hesitation. I've never seen fuel out of the ground (and into either the wings or the bowser then the wings) below about 5C or so and that's in Toronto in mid-winter.
Yes, the skin of an aircraft which has just arrived will be very cold indeed and the fuel will be cold-soaked to well below zero. JO points out correctly, that, depending upon the load, adding fuel will of course warm the fuel somewhat. As FullWings states correctly, one cannot be certain what is going on underneath any layer of snow on the wings when at the gate or taxiing out, the crew cannot be certain what any warming of the wings due to uploaded fuel may do, if indeed anything. There are few experts in the cockpit and I venture to say none in training departments who would today pronounce a wing clean "underneath" a light dusting of snow. I recognize that you acknowledge this.
One item which perhaps has not been touched upon is the recirculation of fuel through the IDG Cooling System (heat exchanger) on (at least) the CFM56 installations on the A320, (not sure of others, including Boeing). After engine start, fuel is circulated from the engine high pressure line through the IDG heat exchanger to keep the IDG cool especially at low engine rpm, and is then returned to the outer tanks, (inner tanks on the A330/340), of course warmer than before. The notion has been expressed elsewhere, that even with dry snow and a piercing cold wing, fuel so warmed will in time and where direct contact is had, (which is almost always the case as the outer tanks are always filled and used last), warm the metal and melt the snow until subsequent cold temperatures just above the surface of the wing re-freeze the liquid leaving ice on the wing underneath the "light" snow. I have had discussions on this matter with other Airbus pilots and the concern is especially the outer portion of the wing being susceptible to stall before the inner portion. I add that I know of no cases where this has occurred but we are not experts and must work in a rule-based system.
I understand what you are driving at in various posts and have both heard it said by Captains I used to fly with and have made such a decision myself dozens of years ago on cold wings, very cold day, light, dry snow conditions, (-30 to -40C). It is a decision which at the time, seemed reasonable. Today it is not. I know of no research, no incidents and no concerns backed up with data (and not just opinions, professional or otherwise), that an aircraft wing can be considered contaminated when sprayed with any type of fluid or gel.
After aircraft were caught and the crews (Captain) charged by the Transport Canada "Ice Police" in Toronto for departing with contaminated wings, that was the end of any such "specialist" cockpit decision that the snow will blow off, and today departing with anything on the wings at all is inviting swift and opprobrious remark at best and an accident with enormous liabilities at worst. It simply is not done anymore and anyone who does not speak up is contributing to the outcome. If IB (or any other airline or crew) is embarrassed or unfairly charged in absentia by an anonymous forum it is still far better than killing an airplane load of people over respect for professional courtesy. Virgil Moshansky among many, would concur.
Now I hear your protests regarding adherence to SOPs and respect the fact that you agree with them. So be it. Why continue to defend the indefensible?
Last edited by PJ2; 3rd Jan 2008 at 08:43.