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AA Super 80 Gate Engine Shutdown Proc.  
User currently offlineIAHFLYR From United States of America, joined Jun 2005, 4790 posts, RR: 22
Posted (7 years 11 months 4 days 6 hours ago) and read 2714 times:

I have a good opportunity to observe the Terminal A ramp at IAH where AA parks on the southside which creates the question of why do the Super 80's keep 1 engine running for 3-5 minutes once parked at the jetway, in the chocks, jetway connected, and baggage door open?

I've witnessed this numerous times and only find this to happen with AA and their 80's....CO didn't operate their MD80 fleet in such a manner when they flew them nor do I find the AA B738's doing it either, but that may only be due to the quieter engines on the B738.

Thanks in advance for all ideas and help.  

[Edited 2007-01-23 22:28:19]


Any views shared are strictly my own and do not a represent those of any former employer.
9 replies: All unread, jump to last
 
User currently offlineMX757 From United States of America, joined Aug 2005, 628 posts, RR: 12
Reply 1, posted (7 years 11 months 4 days 6 hours ago) and read 2704 times:

That's a very interesting observation. The only reason I can think why AA leaves an engine running is that the APU is inoperative and they are waiting for external power to be hooked up before shutting down the engine.

How many a/c did you observe?



Is it broke...? Yeah I'll fix it.
User currently offlineIAHFLYR From United States of America, joined Jun 2005, 4790 posts, RR: 22
Reply 2, posted (7 years 11 months 4 days 6 hours ago) and read 2697 times:

Quoting MX757 (Reply 1):
How many a/c did you observe?


Almost everyone of them......but I didn't think about the APU and it might be to save cycles on the APU and that little bit of fuel it would burn while they are connecting up the ground power! MMMM I don't think that is a likely senario as the extra fuel burned with the engine at idle would seem to be worth more than the APU cycles and fuel burn of the APU!  Confused



Any views shared are strictly my own and do not a represent those of any former employer.
User currently offlineVTBDflyer From Thailand, joined Aug 2006, 379 posts, RR: 0
Reply 3, posted (7 years 11 months 4 days 4 hours ago) and read 2665 times:

Quoting IAHFLYR (Reply 2):
Almost everyone of them......but I didn't think about the APU and it might be to save cycles on the APU and that little bit of fuel it would burn while they are connecting up the ground power! MMMM I don't think that is a likely senario as the extra fuel burned with the engine at idle would seem to be worth more than the APU cycles and fuel burn of the APU!

It does take a little while for the APU to start up, so for a short period of time both the engines and APU are running. But, I'm not sure that it would make a huge difference in dollars lost.

VTBDflyer



Fly Thai
User currently offlineMX757 From United States of America, joined Aug 2005, 628 posts, RR: 12
Reply 4, posted (7 years 11 months 4 days 4 hours ago) and read 2651 times:

Quoting VTBDflyer (Reply 3):
It does take a little while for the APU to start up, so for a short period of time both the engines and APU are running. But, I'm not sure that it would make a huge difference in dollars lost.

This sounds like a very likely scenario. I agree with you, I don't think it would make a huge difference either. I guess AA crunched the numbers and decided it was cheaper to leave number 1 engine running instead of cranking the APU.



Is it broke...? Yeah I'll fix it.
User currently offlineAAR90 From United States of America, joined Jan 2000, 3494 posts, RR: 46
Reply 5, posted (7 years 11 months 4 days 1 hour ago) and read 2583 times:

Way...way...way back when I was flying MD80s, AA published an 8 minute break even cost/benefit point for APU vs. one engine idle at the gate. At that time that analysis included the cost of the added APU cycle as well as fuel use. Not sure what the numbers are now or if the S80 fleet even has a published break even number (738s do not); however, it is supposed to be AA policy to NOT operate the APU upon arrival and I suspect the crew was simply waiting for the ground power to be applied.


*NO CARRIER* -- A Naval Aviator's worst nightmare!
User currently offlineIahflyr From United States of America, joined Jun 2005, 4790 posts, RR: 22
Reply 6, posted (7 years 11 months 4 days ago) and read 2563 times:

Quoting AAR90 (Reply 5):
however, it is supposed to be AA policy to NOT operate the APU upon arrival and I suspect the crew was simply waiting for the ground power to be applied.

Thank you very much for your insight.



Any views shared are strictly my own and do not a represent those of any former employer.
User currently offlineTWAL1011727 From United States of America, joined Mar 2006, 637 posts, RR: 0
Reply 7, posted (7 years 11 months 11 hours ago) and read 2296 times:

Most newer style (less than 20 yrs old) jetbridges have a circuit that will not allow the jetbridge to move towards the A/C if the power cable is lowered. When the power is turned on total movement of the jetbridge is inhibited.
This is so a gate agent cannot pull the jetbridge off the A/C while the power is still connected to the A/C.

Airlines that want to save cycles/fuel on the APU will leave the APU off and accept an engine running the 1-3 minutes it takes to hook up power

KD


User currently offlineSlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 68
Reply 8, posted (7 years 11 months 10 hours ago) and read 2284 times:

Quoting AAR90 (Reply 5):
policy to NOT operate the APU upon arrival and I suspect the crew was simply waiting for the ground power to be applied.

That was my first thought. Coupled with this fact:

Quoting TWAL1011727 (Reply 7):
jetbridges have a circuit that will not allow the jetbridge to move towards the A/C if the power cable is lowered.

A couple other things that might be going on at some airport or other out there in the world are Union slowdowns by certain ground personnel and local airport noise regulations prohibiting the running of APUs unless ground power and air are not available.



Happiness is not seeing another trite Ste. Maarten photo all week long.
User currently offlineFlametech21 From United States of America, joined Sep 2006, 47 posts, RR: 0
Reply 9, posted (7 years 10 months 3 weeks 5 days ago) and read 2086 times:

Wow, I somehow missed this one.

AAR90 is correct, we are under strict orders not to run the APU at the ramp. It is unwritten law to leave the taxi engine running until external power is hooked up. And at some airports such as IAH, that can take a few minutes.

FYI the S80's do not have a specific break even number, although there is simple equation you can use to calculate a ballpark estimate.

Sean, an AA ops eng.



They build them to a higher standard at Long Beach!
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