Cowls=Engine Nacelle. So Engine Anti-Ice.Martin.

So if it is dry, irregardless of temp, anti-ice controls off?Thanks,Eric

Yes.

So if it is dry, irregardless of temp, anti-ice controls off?

To clarify, just in case someone stumbles by this and is confused as to why Peter said yes:Ice = Water + ColdWithout either element, ice cannot exist.If it's not cold, it's just water. If there's no water, there's no ice - it's just cold.The plane doesn't need to be protected from cold so much. Ice can make it fall out of the sky, though, so that's why we have AI.This is why the normal rule of thumb (varies depending on the operator) is:Less than +10C and visible moisture.

Greatly simple and greatly understandable, Kyle. Thumbs up.

This is a great thread, thanks everyone, I'm learing a lot here!

Greatly simple and greatly understandable, Kyle. Thumbs up.

Thanks Peter.

At American we use the enginge anti ice as you described. For wing anti ice we are supposed to use it on the ground any time the engine anti ice is turned on unless the wing has been deiced with type II or IV deice fluid. In flight we use it as a deicer. We let the ice build a bit before we turn it on. I believe this the Boeing procedure but I'm not sure. I don't know why they do it this way because in the 727 and F100 we just turned it on and used as anti ice.

Almost the same at Alaska. No WAI ON on the ground if I, II, or IV is used.

will you really risk damaging the packs if you have them in Auto/High even when the APU nor the engines are running?

All you are really doing is commanding the pack valves open, and if there's no air it just doesn't work. Not really hurting anything.Edit: Just read this in the -300/4/5 MM:

CAUTION: DO NOT OPERATE AN AIR CONDITIONING PACK AND A GROUND CONDITIONED AIRSOURCE AT THE SAME TIME. THE AIR CONDITIONING PACK CANNOT CONTROL THEAIR TEMPERATURE IF YOU ALSO OPERATE A GROUND CONDITIONED AIR SOURCEAT THE SAME TIME. YOU CAN CAUSE DAMAGE TO EQUIPMENT IF YOU OPERATEAN AIR CONDITIONING PACK AND GROUND CONDITIONED AIR SOURCE AT THESAME TIME.

This is if you had pneumatic supply available with the pack running and external A/C...so I think you are stills safe.The only thing is when using external conditioned air you be wary of pressurizing the aircraft with all the doors and windows closed....resulting in a rude surprise for the next rampy to come up and open the door after cooling the aircraft off (if he can get it open...which he won't if it's actually pressurized).You can supply power to the aircraft then open the outflow valve in the manual pressurization mode...or do what normal people do and just crack open a door or flight deck window ;).

Edited February 1, 201214 yr by Houghton11

:( OK, got it!

A quick follow-up question on anti-ice, when you're flying in icing conditions and thus have the wing- and engine anti-ice switched ON when do you switch them OFF in real world OPS - right after you landed together with the pitot tube heaters or do you keep them ON until you shut down the engines at the gate?

A quick follow-up question on anti-ice, when you're flying in icing conditions and thus have the wing- and engine anti-ice switched ON when do you switch them OFF in real world OPS - right after you landed together with the pitot tube heaters or do you keep them ON until you shut down the engines at the gate?

If icing conditions are present or are anticipated on the ground, you will turn anti-ice OFF after you pull up to the gate.

Ok, thanks for confirming!

At our airline, the anti ice is turned off when we exit icing conditions. We don't wait until we're on the ground to turn them off. If we takeoff out of detroit where it's snowing, the a/i is on, but that doesn't mean it stays on all the way to Miami where it's sunny and 70 deg F.If the a/i is on because we're landing in icing conditions then the wings are turned off during the After Landing checklist. If icing conditions (according to that ground-cowl definition I gave earlier) are present, then the cowls stay on until 1) the icing conditions are no longer present, or 2) the engine is shut down. We single-engine taxi a lot both before takeoff and after landing, so if we shut one engine down while taxiing, then the associated cowl a/i is turned off as well. Once we are at the gate, all a/i is turned off during the Shutdown checklist. That includes wing, cowl, and probes. If we are doing a turn in the plane, the probes are usually either just left on, or turned back on within a few minutes of being turned off. They should be on for the Before Start checklist, and we get the flow done for that pretty early.

Thanks for taking your time and share with all of us!One question regarding the probes, I learned somewhere you should wait to turn them ON until after pushback to lessen the risk of ground crew burning themselves and likewise and for the same reason switch them OFF after vacating the runway after landing but you say you sometimes keep them ON. I suppose this is like you say when you're doing a short turn around stop only and maybe the ground crew's duties around the a/c is not the same as when you're doing a full stop?

Ground crews are taught they're hot and to not touch them, for what it's worth, and they're not really in their way. You'd have to go out of your way to grab one.