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convair880mfan
Topic Author
Posts: 324
Joined: Fri Jun 25, 2021 12:33 am

Short haul climb and cruise question...

Sat Dec 25, 2021 6:32 pm

Many years ago I was on a very short flight from Phoenix to Tuscon on an American Boeing 727-200. The plane climbed and descended but there seemed to be no cruise portion of flight [based on my perception of changes in engine pitch]. This also happened while I was on a Delta DC-9-10 flight from Boston to Manchester, New Hampshire. I am wondering why these aircraft seemed [?] to omit the cruise portion. Would there or would there not be some fuel savings if there was some cruise flight?
 
FlyHossD
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Re: Short haul climb and cruise question...

Sat Dec 25, 2021 7:18 pm

The most efficient profile is to climb as weight permits (so a continuous climb), then descend at idle thrust. Of course, traffic and therefore, ATC, limits that possibility.
 
convair880mfan
Topic Author
Posts: 324
Joined: Fri Jun 25, 2021 12:33 am

Re: Short haul climb and cruise question...

Sat Dec 25, 2021 7:21 pm

So cruising flight is just an unavoidable expense that more long haul flights must endure? Ideally they would climb and climb and climb if they could and then descend without any cruise segment? I didn't realize that. Thanks.
 
GalaxyFlyer
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Joined: Fri Jan 01, 2016 4:44 am

Re: Short haul climb and cruise question...

Sat Dec 25, 2021 9:02 pm

FlyHossD wrote:
The most efficient profile is to climb as weight permits (so a continuous climb), then descend at idle thrust. Of course, traffic and therefore, ATC, limits that possibility.


Which is the cruise/climb profile the Concorde flew, temp permitting until reaching descent point. Often, in the Global we’d get a block in the mid-40s and cruise climbing 200-300 fpm at cruise Mach until reaching F470.
 
AndrewJM70
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Re: Short haul climb and cruise question...

Sun Dec 26, 2021 12:37 am

I was on a one hour 757 flight from Aberdeen to London once. We climbed to FL410 and stayed there for two minutes! I was lucky enough to be in the jump seat for that flight and the pilots told me if was the most fuel efficient profile.
 
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Starlionblue
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Re: Short haul climb and cruise question...

Sun Dec 26, 2021 1:30 am

convair880mfan wrote:
So cruising flight is just an unavoidable expense that more long haul flights must endure? Ideally they would climb and climb and climb if they could and then descend without any cruise segment? I didn't realize that. Thanks.


Well, not quite. There's no point climbing above the optimum cruise altitude for the conditions, at least from a fuel burn perspective. Said altitude does tend to increase as you burn of fuel, though.
 
FlyHossD
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Re: Short haul climb and cruise question...

Sun Dec 26, 2021 2:42 am

Starlionblue wrote:
convair880mfan wrote:
So cruising flight is just an unavoidable expense that more long haul flights must endure? Ideally they would climb and climb and climb if they could and then descend without any cruise segment? I didn't realize that. Thanks.


Well, not quite. There's no point climbing above the optimum cruise altitude for the conditions, at least from a fuel burn perspective. Said altitude does tend to increase as you burn of fuel, though.


Correct. As fuel burns off, the optimum altitude increases although slowly. In that situation, a block of cruise altitudes is very useful. We both know that they're not often available, though.
 
GalaxyFlyer
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Re: Short haul climb and cruise question...

Sun Dec 26, 2021 4:20 am

They are in the forties.
 
N1120A
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Re: Short haul climb and cruise question...

Mon Dec 27, 2021 6:56 pm

Southwest used to cruise on LAS-L.A. Basin routes at like FL230-280 in their 737 Classics. When they got the NG, especially with winglets, they started doing those short flights at FL400-FL410 all the time.
 
e38
Posts: 933
Joined: Sun May 04, 2008 10:09 pm

Re: Short haul climb and cruise question...

Mon Dec 27, 2021 7:34 pm

FlyHossD wrote:
The most efficient profile is to climb as weight permits (so a continuous climb), then descend at idle thrust


convair880mfan (topic author), also, reference "parabolic trajectory" in terms of energy efficiency.

e38
 
johns624
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Re: Short haul climb and cruise question...

Mon Dec 27, 2021 8:15 pm

I just flew a DL 321 DTW-LGA. We climbed to FL370, were there only a couple of minutes and then started our descent.
 
phllax
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Joined: Wed Jan 11, 2006 6:53 am

Re: Short haul climb and cruise question...

Tue Dec 28, 2021 1:30 am

N1120A wrote:
Southwest used to cruise on LAS-L.A. Basin routes at like FL230-280 in their 737 Classics. When they got the NG, especially with winglets, they started doing those short flights at FL400-FL410 all the time.


Must depend on weather and/or departure from, especially from LAX. If LAX gives you the LOOP, then it's possible, as you need to be at 10,000 when you hit the beach on the turn back.. Most of the time it's in the 20's and occasionaly up to the mid-30'.
 
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DocLightning
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Re: Short haul climb and cruise question...

Tue Dec 28, 2021 4:03 am

Don't some engine manufacturers recommend a short period of cruise before descending to allow the engines to equilibrate or something?
 
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77west
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Re: Short haul climb and cruise question...

Tue Dec 28, 2021 4:21 am

DocLightning wrote:
Don't some engine manufacturers recommend a short period of cruise before descending to allow the engines to equilibrate or something?


I learned a new word today, thanks. I can't think of any engines that specify a cruise portion, but I know Aloha found the 737NG didn't like the short island hopping they did, although this may have been more to do with cool-down time on the ground.
 
phllax
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Joined: Wed Jan 11, 2006 6:53 am

Re: Short haul climb and cruise question...

Tue Dec 28, 2021 5:33 am

77west wrote:
DocLightning wrote:
Don't some engine manufacturers recommend a short period of cruise before descending to allow the engines to equilibrate or something?


I learned a new word today, thanks. I can't think of any engines that specify a cruise portion, but I know Aloha found the 737NG didn't like the short island hopping they did, although this may have been more to do with cool-down time on the ground.


It was the short ground time and high number of daily legs which cooked the engines on both the 400 and 700.
 
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77west
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Re: Short haul climb and cruise question...

Tue Dec 28, 2021 9:57 am

phllax wrote:
77west wrote:
DocLightning wrote:
Don't some engine manufacturers recommend a short period of cruise before descending to allow the engines to equilibrate or something?


I learned a new word today, thanks. I can't think of any engines that specify a cruise portion, but I know Aloha found the 737NG didn't like the short island hopping they did, although this may have been more to do with cool-down time on the ground.


It was the short ground time and high number of daily legs which cooked the engines on both the 400 and 700.


Interesting, didn't know they operated the -400 thought it was from the -200 to the -700. But goes to show how modern engines seem to be gravitating towards longer legs - how is the A220 holding up in this respect? Given the -100 is positioned as a regional 100 seater.
 
e38
Posts: 933
Joined: Sun May 04, 2008 10:09 pm

Re: Short haul climb and cruise question...

Tue Dec 28, 2021 9:52 pm

phllax wrote:
If LAX gives you the LOOP


phllax, I understand the context of the climb out of KLAX on the Loop departure.

Just fyi, the Loop departure is rescinded; replaced with RNAV - ORCKA5 departure. Still cross the coastline (KLIPR intersection) at or above 10,000 feet.

e38

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