Right.In our airline we are not authorized to use Engine and Wing Anti- Ice at the same time.

Yikes. On the 737? That sounds like a recipe for trouble. What do you do inflight if you're picking up icing and you need to de-ice the wing? Do you really turn off the engine AI?

Yikes. On the 737? That sounds like a recipe for trouble. What do you do inflight if you're picking up icing and you need to de-ice the wing? Do you really turn off the engine AI?

We can turn both on but not on takeoff. We can do that for 757, 767 and 777 only (I hope on arriving 787 too :)). We use Clean wing concept. Before t/off iceman inspect the wings and if no ice we can blast off. After wheels up crew my do whatever they want. I will ask pilots today for clarification.

Spin737, my post was a general aircraft anti ice post. I did point out the performance limited issues. Seems the 737 falls into this case. take a look at these limitations Engine anti-ice must be on when icing conditions exist or are anticipated, except during climb and cruise below -40°C SAT.Use of wing anti-ice above FL350 may cause bleed trip off and possible loss of cabin pressure. (SP.16.8) The limitations further stated that wing anti-ice must be on, on the ground during icing conditions. Seems some operators leave it off in this situation if de-icing is performed. Interesting that wing anti ice is inhibited with the throttles at takeoff position. I did notice that the stick shaker is adjusted to icing condition speeds when the wing anti ice switch is turned on in flight. Sounds like the penalty on the engines is so large that the wing anti ice is indeed used for de-icing after ice accumulation. This also make some pilots more reluctant to use it. I don't mess around with icing. The airfoil takes a big hit in performance during accumulation. Stall speed creeps up on you in those situations.

Icing guidelines are always being re-drawn. It's hard to keep up to date.

The limitations further stated that wing anti-ice must be on, on the ground during icing conditions.

That's interesting. I've never seen that one. Our company is getting ready to officially say that you don't use wing AI on the ground. Their logic being, that if you need wing AI, you need to be de-iced. And if you have de-icing fluid on your wings (all types now), don't use wing AI.

Interesting that wing anti ice is inhibited with the throttles at takeoff position.

There's at least two options for this on the 737:

1. It stays on during take-off;
2. The WAI valve closes with T/O thrust set and the WAI switch clicks off when airborn.

My airline opts for 2. The logic there is that if the plane can't roll down the runway and get up to the thrust reduction height without WAI, then you shouldn't be taking off. Interesting stuff, and it's about time the yearly De-icing tests come out for the airlines.

The WAI valve closes with T/O thrust set and the WAI switch clicks off when airborn. My airline opts for 2. The logic there is that if the plane can't roll down the runway and get up to the thrust reduction height without WAI, then you shouldn't be taking off.

What does that mean? Do you have like a solenoid held WAI switch, similar to the A/T or start sws?

What does that mean? Do you have like a solenoid held WAI switch, similar to the A/T or start sws?

Hmm. That's a good question. I'm not sure, but I'd guess that it's not latched closed like the A/T but it's opened like the Start Switches. (The A/T requires power to be on. During start, the Start Switches will stay in Ground until it gets power to go to off, I believe.)

There's at least two options for this on the 737:

1. It stays on during take-off;
2. The WAI valve closes with T/O thrust set and the WAI switch clicks off when airborn.

My airline opts for 2. The logic there is that if the plane can't roll down the runway and get up to the thrust reduction height without WAI, then you shouldn't be taking off.

First, please forgive my ignorance... and having said that, for me this is one of the best topics in the forum! Thanks so much to everyone who is contributing, it's VERY educational for me. I have a question on Number 2, and again, forgive me (most obvious) ignorance. If I'm understanding correctly, if the wing has ice build up, then you de-ice with de-icing fluid. That assumed, if you're ready for takeoff, the wing should be clear of ice. If its clear of ice, then do you need Wing A/I turned on? Is this due to the increased air speed going over the wing and moisture you might experience while penetrating clouds after takeoff? Also, if I understand correctly, Wing A/I it's inhibited with take off thrust set. So after take off and thrust reduced, would the Wing A/I switch back on, and wouldn't you want that to occur if you're likely to be in icing conditions? Thanks in advance for answering my questions! I really appreciate your time!

If I'm understanding correctly, if the wing has ice build up, then you de-ice with de-icing fluid. That assumed, if you're ready for takeoff, the wing should be clear of ice. If its clear of ice, then do you need Wing A/I turned on?

I think your one answer is already above, if I'm not mistaken:

That's interesting. I've never seen that one. Our company is getting ready to officially say that you don't use wing AI on the ground. Their logic being, that if you need wing AI, you need to be de-iced. And if you have de-icing fluid on your wings (all types now), don't use wing AI.

BTW Why do you think air speed over the wing increases?

I have a question on Number 2, and again, forgive me (most obvious) ignorance. If I'm understanding correctly, if the wing has ice build up, then you de-ice with de-icing fluid. That assumed, if you're ready for takeoff, the wing should be clear of ice. If its clear of ice, then do you need Wing A/I turned on? Is this due to the increased air speed going over the wing and moisture you might experience while penetrating clouds after takeoff?

The WAI can be on for taxi, but it'll turn off with the application of power. The thinking at my airline is that the wing needs to be clean to takeoff through the de-ice/anti-ice process. Then, if you can't get airborn and up to the thrust reduction height without WAI, then you're in severe icing and you should not take off.

Also, if I understand correctly, Wing A/I it's inhibited with take off thrust set. So after take off and thrust reduced, would the Wing A/I switch back on, and wouldn't you want that to occur if you're likely to be in icing conditions? Thanks in advance for answering my questions! I really appreciate your time!

The valve that let's the bleed air in to the wing closes with a certain T/L angle. If you reduced the T/L angle without taking off, the valve would open again. When the jet becomes airborn, the switch moves to the off position and would need to be turned on again by the crew.

Hey spin, what is the thrust rating on your 37s?

Hmm. That's a good question. I'm not sure, but I'd guess that it's not latched closed like the A/T but it's opened like the Start Switches. (The A/T requires power to be on. During start, the Start Switches will stay in Ground until it gets power to go to off, I believe.)

Ehh. Interesting, Matt, I should've read the book first I guess. I thought that was probably an option on your line or so, didn't realize it was part of the normal system, and is indicated as such in the books. Never paid much attention to it... But the switch tripping off seems to be standard then. However the other book says it's a "CB" type switch and seems indeed to be solenoid controlled. Well never mind, case closed I guess. Will try it out in the sim though and see what it does.

Hey spin, what is the thrust rating on your 37s?

Last place I flew had -800 and-900 with the cheapo 22k and 24k derates. Now I'm flying -400 and -7, -8, and -900s. The -4 are 20 and 22k and the NGs vary all the way to the 27k bump.

Last place I flew had -800 and-900 with the cheapo 22k and 24k derates. Now I'm flying -400 and -7, -8, and -900s. The -4 are 20 and 22k and the NGs vary all the way to the 27k bump.

Nice. The dc10-30 and the 5/550 are over powered. I flew C-141s and she was a pig at max weight, lots of step climbing when crossing the pond. The dc10 could fly single engine and perform single engine go-arounds at 460,000. On my last dc10 flight i had it at 35 degrees nose high chasing V2+10, 35 was as far as i would take it. I have seen it at 45 degrees with only 15,000 pounds of gas. In the G-5 i normally get 4,000 to 6,000 feet per minute after lift off.

That's insane... Wish I had the chance to witness that raw performance live.

That's insane... Wish I had the chance to witness that raw performance live.

At light weights we played a game with the new guys called "I bet you cant keep V2+10". I would place a simulated obstacle at the end of the runway which would give you numbers for a flap setting between 5 to 7 degrees. The jet would rocket up after lift off. New guys would get nervous at 25 degrees and give up. I myself would get nervous at 35 degrees and stop the chase. The KDC-10 guys will go up to 45. I've seen this once. The video below shows them going to 45 after a low pass. I truly loved flying the 10.http://youtu.be/VEdH7b3OdC8

Nice. The dc10-30 and the 5/550 are over powered.

If you want to fly an overpowered 737, you have to fly the 757. ;) The -700 has some get up and go, but the -900 can be a pig.