dcaord
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WN Climb Rate

Wed Jun 26, 2013 12:30 am

I've noticed, consistently over many years, WN flights seems to take of and climb at a significantly steeper rate than other airlines. I would have never thought that this is something that could vary airline to airline, but rather might be based off airport or aircraft. That being said, I have noticed now on dozens of WN flights out of a wide range of airports, it seems to be consistent that W9 737s climb faster and steeper than others. Is this accurate? If so, whats the reasoning?

[Edited 2013-06-25 18:09:16]

[Edited 2013-06-25 18:09:34]
 
b747400erf
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RE: W9 Climb Rate

Wed Jun 26, 2013 12:38 am

I do not know who W9 is either, but my guess is they might not use a derated climb while other airlines you fly, do?
 
dcaord
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RE: W9 Climb Rate

Wed Jun 26, 2013 12:39 am

Apologies....WN

Filler

Filler

Filler
 
flymia
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RE: W9 Climb Rate

Wed Jun 26, 2013 12:39 am

W9 as in Air Bagan??

I am guessing maybe WN is what you meant to type?

Maybe what ever airline you are referring to uses a higher than usual cost index when programing the FMC.
If it is WN it could also be that they do more shorter haul flights than most airlines which means a lot less fuel for flights. Less fuel, less weight, higher rate of climb.
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b747400erf
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RE: W9 Climb Rate

Wed Jun 26, 2013 1:05 am

Well for WN, I don't believe they carry the amount of cargo that other airlines carry. So their gross weight is going to be lower than a similar 737 from United or American. They probably use a higher cost index and no derated climb mode also.
 
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Starlionblue
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RE: WN Climb Rate

Wed Jun 26, 2013 1:14 am

Quoting B747400ERF (Reply 5):

Well for WN, I don't believe they carry the amount of cargo that other airlines carry. So their gross weight is going to be lower than a similar 737 from United or American. They probably use a higher cost index and no derated climb mode also.

Cargo being less I can understand. Lower weight means higher climb rate. The faster you can get to altitude in a jet, the lower your total fuel burn.

However not using derate when possible is not very rational. The maintenance savings are rather large despite the higher fuel costs.
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Goldenshield
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RE: WN Climb Rate

Wed Jun 26, 2013 1:46 am

Quoting B747400ERF (Reply 5):

Well for WN, I don't believe they carry the amount of cargo that other airlines carry.

Actually, you'd be surprised at just how much cargo they DO carry.
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BoeingGuy
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RE: WN Climb Rate

Wed Jun 26, 2013 2:43 am

Quoting B747400ERF (Reply 2):
but my guess is they might not use a derated climb while other airlines you fly, do?

Actually from what I understand WN has "power by the hour" maintenance agreements in which they always use derated climb and takeoff thrust. Not sure about the 737, but the climb derate washes out between 10,000 and 12,000 feet on many Boeing airplanes (10-30K as an option).

Quoting Starlionblue (Reply 6):
However not using derate when possible is not very rational. The maintenance savings are rather large despite the higher fuel costs.

Yep, I know that's counter-intuitive, but a derated climb actually uses a bit more fuel than un-derated climb.
 
LH707330
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RE: WN Climb Rate

Wed Jun 26, 2013 6:52 am

Quoting BoeingGuy (Reply 8):
Yep, I know that's counter-intuitive, but a derated climb actually uses a bit more fuel than un-derated climb.

How is it counter-intuitive? Most engines get better SFC under load and burn less high up, it's the same concept as accelerating to get through a yellow light instead of waiting for the next phase at idle.

Edit: Are you suggesting that it's counter-intuitive because the instantaneous burn is higher?

[Edited 2013-06-25 23:53:50]
 
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Starlionblue
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RE: WN Climb Rate

Wed Jun 26, 2013 4:24 pm

Quoting LH707330 (Reply 9):
Quoting BoeingGuy (Reply 8):
Yep, I know that's counter-intuitive, but a derated climb actually uses a bit more fuel than un-derated climb.

How is it counter-intuitive? Most engines get better SFC under load and burn less high up, it's the same concept as accelerating to get through a yellow light instead of waiting for the next phase at idle.

Edit: Are you suggesting that it's counter-intuitive because the instantaneous burn is higher?

It's perfectly clear if you've studied jet engines, but if you are a layman it can "make more sense" that climbing slower uses less fuel.
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BoeingGuy
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RE: WN Climb Rate

Wed Jun 26, 2013 6:14 pm

Quoting LH707330 (Reply 9):
Edit: Are you suggesting that it's counter-intuitive because the instantaneous burn is higher?
Quoting Starlionblue (Reply 10):
It's perfectly clear if you've studied jet engines, but if you are a layman it can "make more sense" that climbing slower uses less fuel.

Correct. Even a layman can deduce that climbing at a lower thrust setting burns less fuel instantaneously. It takes an expert like one of us to realize that getting to a more efficient cruise altitude faster ultimately burns less fuel and makes an underated climb burn less fuel in total.
 
Sancho99504
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RE: WN Climb Rate

Sun Jun 30, 2013 9:51 pm

WN has places to go and they don't have time to lolly gag around. Time is money. Ever watch them taxi around?
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seabosdca
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RE: WN Climb Rate

Sun Jun 30, 2013 10:05 pm

They (mostly) fly aircraft with better thrust-to-weight ratios than other operators.

Their 73Gs are hot rods, and their 733s also do better than much of the heavier competition, especially at lower altitudes.

Everyone else is using 738s/739s and A320s/A321s that don't have quite the same shove in the back.

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