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HAWK21M
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Window Heat - Switched Of - When

Mon Dec 17, 2012 7:28 pm

Another SOP is B737...Window heat switched off as part of post shutdown checks during transit halts....On the B757 it stays on throughout until the last flight of the day.
How is it on the other types & at other places.
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Dogbreath
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RE: Window Heat - Switched Of - When

Tue Dec 18, 2012 7:59 am

I currently fly the B737-800 and we keep our Window Heat ON during turnarounds. We only select it OFF after the last sector and final shutdown checks.
This was the same on the B747, which I flew before the B738.
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b78710
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RE: Window Heat - Switched Of - When

Tue Dec 18, 2012 5:53 pm

We have no procedure to deselect it on the 744, though I usually do on layovers or if its raining and steaming away.

deselection is accompanied by a status message so no chance of it being left off.

our 340's i never touch as its automatically selected off on the ground
 
N243NW
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RE: Window Heat - Switched Of - When

Tue Dec 18, 2012 6:44 pm

Our 757/767 SOP is to turn window heat off after each flight. It's in the parking checklist.
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Acey559
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RE: Window Heat - Switched Of - When

Wed Dec 19, 2012 2:36 am

On the Embraer 145 we select it on as part of the before takeoff check and off after we clear the runway. Another airline flying the same aircraft turns it on right after engine start. A lot just depends on the airline procedure.
 
ROSWELL41
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RE: Window Heat - Switched Of - When

Wed Dec 19, 2012 3:53 am

On the A320, window and pitot/probe heat is automatically controlled. You can turn it on if you need to melt snow on the windscreen while parked at the gate.
 
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HAWK21M
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RE: Window Heat - Switched Of - When

Wed Dec 19, 2012 6:44 am

Quoting Acey559 (Reply 4):
A lot just depends on the airline procedure.

Exactly why the OP was made....to get to know the SOPs worldwide and its thought behind it being followed.
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SUPRAZACHAIR
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RE: Window Heat - Switched Of - When

Tue Dec 25, 2012 8:41 pm

On the dash, our procedure is windshield heat to "warm up" during the before taxi flow, and back off as part of the parking flow. After 30 seconds in warm-up it is switched to "norm" if taxiing/taking off into icing conditions.
 
highflyer9790
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RE: Window Heat - Switched Of - When

Wed Dec 26, 2012 12:52 am

on the CRJ our window heat stays on from first flight of the day until the terminator.

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JBirdAV8r
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RE: Window Heat - Switched Of - When

Wed Dec 26, 2012 1:52 am

Quoting highflyer9790 (Reply 8):
on the CRJ our window heat stays on from first flight of the day until the terminator.

Highlfyer

In the summer months at my airline, we turn it off in the shutdown flow if the OAT was over 26C...lest we get the windshield heat caution messages on the taxi-out. It goes back on in the before takeoff checklist.

If it's particularly hot, we can take off with the windshield heat OFF as long as we put it on in the after takeoff checks.
I got my head checked--by a jumbo jet
 
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HAWK21M
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RE: Window Heat - Switched Of - When

Thu Dec 27, 2012 11:13 am

Quoting JBirdAV8r (Reply 9):
In the summer months at my airline, we turn it off in the shutdown flow if the OAT was over 26C...lest we get the windshield heat caution messages on the taxi-out. It goes back on in the before takeoff checklist.

Wouldn't the WHCU ensure the heat to the windshield is modulated to prevent an overheat.
I may not win often, but I damn well never lose!!! ;)
 
JBirdAV8r
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RE: Window Heat - Switched Of - When

Thu Dec 27, 2012 7:13 pm

Quoting HAWK21M (Reply 10):
Wouldn't the WHCU ensure the heat to the windshield is modulated to prevent an overheat.

In theory, yes--it's designed to do just that. But in practice when the OAT is very high (generally >30C) and we're on the ground, the windshield temperature controllers have difficulty controlling the temperature and we'll get a caution message (L or R WSHLD HEAT). Sometimes simply recycling the windshield heat to OFF and then back to LOW will clear the error, but often times it'll come right back up again. So we try to limit the time that windshield heat is on when we're on the ground.

During the extremely hot days this past summer it wasn't uncommon to see ice bags on the windows of some CRJs.
I got my head checked--by a jumbo jet
 
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HAWK21M
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RE: Window Heat - Switched Of - When

Thu Dec 27, 2012 7:28 pm

Quoting JBirdAV8r (Reply 11):
So we try to limit the time that windshield heat is on when we're on the ground.

What would be the cutoff temp of the window heat approx......
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JBirdAV8r
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RE: Window Heat - Switched Of - When

Thu Dec 27, 2012 10:27 pm

Quoting HAWK21M (Reply 12):
What would be the cutoff temp of the window heat approx......

I'm not sure what the overheat detection tolerance is....I'll see if I can find something that would tell me. The LOW setting regulates windshield/window temperature to 24C, and the HIGH setting (we only use for as long as we need it) maintains the windshields at 41C and windows at 24C.

When we put the windshield heat in OFF/RESET, it resets the overheat detection logic.
I got my head checked--by a jumbo jet

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