What is the correct positions for the packs and isolation valve when parked at the gate with external air conditioning unit connected?Then to anti-ice...have read lots of posts about this and also checked the doc but I'm still a bit confused...could someone who really knows for fact or even better a real driver tell me in short words what the correct procedure is for using wing and engine anti-ice during cold weather operation?When should the wing/engine anti-ice switches be turned ON/OFF during the different phases of a normal flight...taxi, t/o, climb, cruise, descent, landing, taxi...?Thanks in advance!

Edited January 31, 201214 yr by WebMaximus

There is a lot to be said about the pace of the AOA training but this subject was (imho, i am not a real world 737 pilot) i think properly explained there.Too much to point out here but in shortBelow 10 OAT and moisture put anti-ice on.Again the training explains it much better

OK, I'll check that AOA course once again.Anyone regarding the packs and isolation valve when you have the external air conditioning unit connected?

Packs auto, isolation valve open if i'm right (but i might be wrong :d)

If I read Chris Brady's tech guide correctly, the conditioned ground air goes straight into the mixing manifold and from there into the cabin. According to AoA, having the packs on whilst ground air on is connected can overboost the packs and damage them.Although the AoA "originator flow" video has the isolation valve set to open, the schematic in the tech guide suggests that the isolation valve is on the other side of the "circuit" to the ground air - itself isolated by the "off" packs - and that its position therefore should not make any difference. Of course, someone who actually knows what they are talking about (ie not me) might be able to give authoritative advice...Cheers,Jeff

If using external air conditioning the position of the isolation valve or other bleed valves does not matter. External A/C is delivered directly to the mix manifold well downstream of any of the pneumatic system packs and valves. Your packs should be off though as there is no air to operate the ACMs...unless you have APU, external pneumatic, or engine bleed air availible...even operating the packs whilst using external conditioned air can not be good for things.

I watched the AoA anti-ice lesson again and it does (as always when it's made my AoA) give you great detail about the systems but very little on the actual operation of the systems on a normal flight, guess we'll see more of that in the FlightWork section once those lessons become available. After doing some more reading in the FCOM1 what I understand is:

• Engine anti-ice should be ON during all phases of flight when temp is between +10C and -40C. If the temp is lower than -40C it should not be used during climb and cruise
• Wing anti-ice should be ON during all phases of flight when the temp is between +10C - -40C except for during t/o when it will be automatically switched OFF if you don't switch it OFF yourself. You will then have to manually switch it back ON after t/o if needed

Regarding the packs and isolation valve when using an external air condition unit thanks Jeff and Patrick! One thing though, will you really risk damaging the packs if you have them in Auto/High even when the APU nor the engines are running? No big deal since I know they should be OFF now, just curious...

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.

I watched the AoA anti-ice lesson again and it does (as always when it's made my AoA) give you great detail about the systems but very little on the actual operation of the systems on a normal flight, guess we'll see more of that in the FlightWork section once those lessons become available. After doing some more reading in the FCOM1 what I understand is:

• Engine anti-ice should be ON during all phases of flight when temp is between +10C and -40C. If the temp is lower than -40C it should not be used during climb and cruise
• Wing anti-ice should be ON during all phases of flight when the temp is between +10C - -40C except for during t/o when it will be automatically switched OFF if you don't switch it OFF yourself. You will then have to manually switch it back ON after t/o if needed

Regarding the packs and isolation valve when using an external air condition unit thanks Jeff and Patrick! One thing though, will you really risk damaging the packs if you have them in Auto/High even when the APU nor the engines are running? No big deal since I know they should be OFF now, just curious...

Not sure if this is correct my friend.A ryanair pilot said the wing is used very rarely, and its completely down to the airline on what positive degrees the anti ice comes on, I know airlines that use +4 +6 etc..Alex

I wrote this moments ago in another topic (http://forum.avsim.net/topic/346428-anti-ice/page__view__findpost__p__2244017):I can't speak for any other airline, but for us:Cowls:1) On the ground - The cowl anti-ice system must be ON when the OAT is 10°C or below and visible moisture in any form is present (such as fog with visibility of one mile or less, rain, snow, sleet and ice crystals). • The cowl anti-ice system must also be ON when the OAT is 10°Cor below when operating on runways, ramps or taxiways where the surface snow, ice, standing water, or slush is present.2) In the air - Icing conditions exist in-flight at a TAT of 10°C or below, and visible moisture in any form is encountered (such as clouds, rain, snow, sleet or ice crystals), except when the SAT is -40°C or below. • The engine cowl anti-ice system must be ON: – When in icing conditions, or – When ICE is annunciated by the ice detection system.Wing A/I:1) On the ground - The wing anti-ice system must be ON for takeoff when the OAT is 5°C or below and visible moisture in any form is present (such as fog with visibility of one mile or less, rain, snow, sleet and ice crystals). • The wing anti-ice system must also be ON for takeoff when the OAT is 5°C or below and the runway is contaminated with surface snow, slush or standing water. • When Type II, Type III, or Type IV anti-icing fluids have been applied, the wing anti-ice system must only be selected ON, if required, just prior to thrust increase for takeoff.2) In the air - Icing conditions exist in-flight at a TAT of 10°C or below, and visible moisture in any form is encountered (such as clouds, rain, snow, sleet or ice crystals), except when the SAT is -40°C or below. • The wing anti-ice system must be ON: – When ICE is annunciated by the ice detection system, or – When in icing conditions and the airspeed is less than 230 KIAS. • Do not hold in icing conditions with the flaps/slats extended.Just for clarification - When it refers to OAT, that is the temperature you get from ATIS/METAR observations. What you get from the PROG page in the FMS is SAT, and it can only be used for the "in the air" portions where is refers to SAT is -40C or below. This is because the SAT readouts can be wrong when the plane is on the ground. This is more of a RW problem, and it has to do with the probes getting heated by the sun, etc. For instance, 2 days ago I was in KDTW, OAT was 1C according to D-ATIS, and our SAT readout was 9C. This info was written by a lawyer. I know it's not the easiest thing to read, but now you know what it looks like in the manuals. :-)

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.

Thanks Tom!

I wrote this moments ago in another topic (http://forum.avsim.n...ost__p__2244017):I can't speak for any other airline, but for us:Cowls:1) On the ground - The cowl anti-ice system must be ON when the OAT is 10°C or below and visible moisture in any form is present (such as fog with visibility of one mile or less, rain, snow, sleet and ice crystals). • The cowl anti-ice system must also be ON when the OAT is 10°Cor below when operating on runways, ramps or taxiways where the surface snow, ice, standing water, or slush is present.2) In the air - Icing conditions exist in-flight at a TAT of 10°C or below, and visible moisture in any form is encountered (such as clouds, rain, snow, sleet or ice crystals), except when the SAT is -40°C or below. • The engine cowl anti-ice system must be ON: – When in icing conditions, or – When ICE is annunciated by the ice detection system.Wing A/I:1) On the ground - The wing anti-ice system must be ON for takeoff when the OAT is 5°C or below and visible moisture in any form is present (such as fog with visibility of one mile or less, rain, snow, sleet and ice crystals). • The wing anti-ice system must also be ON for takeoff when the OAT is 5°C or below and the runway is contaminated with surface snow, slush or standing water. • When Type II, Type III, or Type IV anti-icing fluids have been applied, the wing anti-ice system must only be selected ON, if required, just prior to thrust increase for takeoff.2) In the air - Icing conditions exist in-flight at a TAT of 10°C or below, and visible moisture in any form is encountered (such as clouds, rain, snow, sleet or ice crystals), except when the SAT is -40°C or below. • The wing anti-ice system must be ON: – When ICE is annunciated by the ice detection system, or – When in icing conditions and the airspeed is less than 230 KIAS. • Do not hold in icing conditions with the flaps/slats extended.Just for clarification - When it refers to OAT, that is the temperature you get from ATIS/METAR observations. What you get from the PROG page in the FMS is SAT, and it can only be used for the "in the air" portions where is refers to SAT is -40C or below. This is because the SAT readouts can be wrong when the plane is on the ground. This is more of a RW problem, and it has to do with the probes getting heated by the sun, etc. For instance, 2 days ago I was in KDTW, OAT was 1C according to D-ATIS, and our SAT readout was 9C. This info was written by a lawyer. I know it's not the easiest thing to read, but now you know what it looks like in the manuals. :-)

Saw your answer in another thread but thanks again Charles :(

Capt Carter,what a superb,and more to the point, definitive answer straight from the horse's mouth, so to speak,rather than all the conjecture floating about. Again, we learn.

What is cowls and where in the A/C do you set Antiice ON for this? or is it part of the same system and buttons as wing and engine antiice?ThanksMichael

What is cowls and where in the A/C do you set Antiice ON for this? or is it part of the same system and buttons as wing and engine antiice?ThanksMichael

Yes Cowls = Engines.

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