Speedbird741
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High Altitude Homebases

Sat Mar 07, 2009 3:26 pm

Hi all:


Pardon me if this has been discussed here before, but i could not find anything on it. Now moving on to the topic.
Do airlines that are based on high altitude airports like South African in JNB or Aeromexico in MEX have specially prepared engines, for high altitude takeoff and landing operations that is, or are the engines regular like on any other aircraft of the same type. If not, what do these airlines do to maximize profit according to constant weight restricted operations.
On a separate note, do other airlines that operate to these airports like BA, LH, IB and so on, have a select number of airframes (once again with special preparation) that are exclusively used for these high altitude destinations ?


I thank you for all your posts, and once again apologize if this has been previously discussed or makes no sense at all



Speedbird741
Boa noite Faro, Air Portugal 257 climbing flight level 340
 
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RE: High Altitude Homebases

Sat Mar 07, 2009 6:22 pm

F9 is based in DEN and they fly some of the same a/c types that my airline (B6) does, but I think on the A320 family they have different engines from us (we have the IAE V2500, I think F9 has the CFMs on their aircraft..please correct me if I am wrong). However, I don't think that they chose the engine specifically because of the higher elevation of DEN. It IS calculated in the takeoff roll distance though.

I can't see having an entire extra engine in the mix as there is soooo much that comes with needing extra engines and spare parts and the (very slim) possibility of hanging the incorrect engine type on an aircraft. Many of the major airports that are at higher elevations have runways that are quite long to support the heavies needing that extra take off roll distance.

I may be wong on this, I mean my airline is based at an airport that is a few feet ASL LOL!

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ZBBYLW
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RE: High Altitude Homebases

Sat Mar 07, 2009 6:29 pm

Well if you look at South African they have primarly 4 engine aircraft which are supiror for take off performance (as far as Vmc Calculations go) so this enables them to fly to Europe very effectivly with those. Also you will notice that BA, LH and so on tend to also use 340s or 747s down there for this same reason. So its not engine selection so much as aircraft selection. I doubt we would see SA get any 777s for this very reason.
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Speedbird741
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RE: High Altitude Homebases

Sat Mar 07, 2009 7:37 pm



Quoting B6JFKH81 (Reply 1):
I think on the A320 family they have different engines from us (we have the IAE V2500, I think SA)">F9 has the CFMs on their aircraft..please correct me if I am wrong).

Correct, but when i say specially prepared engine, i mean the same engine type but specially prepared, let's say for example : both SA and BA use or in case of SA used, RB211 on their 744 fleet, but SA had their engines with specific preparation for high altitude operation.




Thank you for your informative posts




Speedbird741
Boa noite Faro, Air Portugal 257 climbing flight level 340
 
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RE: High Altitude Homebases

Sat Mar 07, 2009 7:59 pm

AM and MX ordered the DC-10-15 instead of the -10. The -15 has more powerful engines, giving them better takeoff performance at MEX. AFAIK, they are the only two airlines that ordered the -15.
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cloudyapple
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RE: High Altitude Homebases

Sat Mar 07, 2009 8:39 pm

Quoting Speedbird741 (Reply 3):
with specific preparation

Depends what you mean by "specific preparation". At hot and high airports you need more thrust - than you'd otherwise need at sea-level airports - for takeoff with a specific payload. You can either choose a higher thrust version of an engine or choose the thrust bump option on the GE90s to give you the boost. I'm not aware you need any other modifications. You either have the thrust or you don't. If you don't your payload take a hit. But higher thrust version of an engine can be selected for all sorts of reasons and not just for hot and high ops.

Also long runways like Dubai's (4300m) help - which goes to mitigate against the need for higher thrust. But then it depends on how much runway you have.

Or else you can go to the extreme - fit some rockets to assist with the takeoff. Google JATO or RATO.

[Edited 2009-03-07 12:51:12]
A310/A319/20/21/A332/3/A343/6/A388/B732/5/7/8/B742/S/4/B752/B763/B772/3/W/E145/J41/MD11/83/90
 
andz
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RE: High Altitude Homebases

Sat Mar 07, 2009 8:49 pm



Quoting Speedbird741 (Thread starter):
high altitude airports

May I be picky? Surely it is high elevation airports? Doesn't altitude only apply when you are actually in the air?
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cloudyapple
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RE: High Altitude Homebases

Sat Mar 07, 2009 8:53 pm

Quoting Andz (Reply 6):
Doesn't altitude only apply when you are actually in the air?

No! In aviation, an airport has an elevation. In general English altitude is a distance measurement with respect to a defined datum (usually MSL or GL). So that's fine.

[Edited 2009-03-07 12:57:15]
A310/A319/20/21/A332/3/A343/6/A388/B732/5/7/8/B742/S/4/B752/B763/B772/3/W/E145/J41/MD11/83/90
 
Speedbird741
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RE: High Altitude Homebases

Sat Mar 07, 2009 9:47 pm



Quoting Cloudyapple (Reply 5):
Depends what you mean by "specific preparation".

Well that really is my doubt, this came up the other day as I went to a presentation in a university, and the professor was an ex TP maintenance engineer, and he mentioned that SA's aircraft have engines prepared and fit for high altitude ops, which left me intrigued as I thought airlines like SA and MX didn't have many options aside from longer runways and higher thrust settings.





Speedbird741
Boa noite Faro, Air Portugal 257 climbing flight level 340
 
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RE: High Altitude Homebases

Sat Mar 07, 2009 10:08 pm

Quoting ZBBYLW (Reply 2):
I doubt we would see SA get any 777s for this very reason.

AeroMexico flies 777s out of MEX, though.

As long as there isn't a big terrain clearance issue any advantages over quads should be limited.

[Edited 2009-03-07 14:09:17]
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Viscount724
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RE: High Altitude Homebases

Sat Mar 07, 2009 10:25 pm



Quoting SLCLAXKIXKHH (Reply 4):
AM and MX ordered the DC-10-15 instead of the -10. The -15 has more powerful engines, giving them better takeoff performance at MEX. AFAIK, they are the only two airlines that ordered the -15.

Only 7 DC-10-15s were built, 2 for AM and 5 for MX. They were basically the DC-10-10 with the more powerful GE CF6-50 engines of the long-range and much higher gross weight DC-10-30, rather than the standard CF6-6 engines of the DC-10-10..
 
citationjet
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RE: High Altitude Homebases

Sat Mar 07, 2009 10:36 pm

I am not sure why your question is limited to airlines "based" at high altitude airports. Even if an airline isn't based at a high altitude airport, there is a good chance that it operates daily to another airport that is high altitude. An airline "based" at a sea level airport with a few flights a day to DEN or MEX for instance, wouldn't have a plane/engine combination dedicated to that single route. One example would be Alaska Airlines, based in Seattle but flies to DEN and MEX, for instance. Another example would be AA, based in DFW which is not high altitude, but flies MIA (at sea level) to La Paz, Bolivia (LPB).

[Edited 2009-03-07 14:47:56]
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DingDong
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RE: High Altitude Homebases

Sat Mar 07, 2009 10:39 pm

How do part 121 operators do it for routine flying in and out of airports above, say, 8,000 feet MSL?

IIRC, as of a few years ago, United didn't want to dispatch to places such as La Paz, Bolivia (LPB, 13,325 feet MSL) unless it was an emergency diversion. Something about a policy of not landing at airports above 8,000 feet otherwise.

Special handling was required for these really high elevation airports. Specific procedures for dealing with the pressure outflow valves were required, I seem to vaguely recall?
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Viscount724
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RE: High Altitude Homebases

Sun Mar 08, 2009 2:58 am



Quoting CitationJet (Reply 11):
Another example would be AA, based in DFW which is not high altitude, but flies MIA (at sea level) to La Paz, Bolivia (LPB).

AA's U.S. predecessors on the South America routes, Braniff and Easter, also served LPB.

Quoting DingDong (Reply 12):
Special handling was required for these really high elevation airports. Specific procedures for dealing with the pressure outflow valves were required, I seem to vaguely recall?

I recall a story, whether true or not I'm not sure, that when the door of Eastern's first flight to LPB was opened on arrival (they initially used the 727 to LPB), the passenger oxygen masks dropped, as the system was set to require oxygen at a lower altitude than LPB's 13,000+ ft. elevation. The story said they had to adjust the system on aircraft used to LPB to avoid that problem.
 
Speedbird741
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RE: High Altitude Homebases

Sun Mar 08, 2009 10:25 am



Quoting CitationJet (Reply 11):
I am not sure why your question is limited to airlines "based" at high altitude airports.

I understand, and that's why I also asked this :

Quoting Speedbird741 (Thread starter):
On a separate note, do other airlines that operate to these airports like BA, LH, IB and so on, have a select number of airframes (once again with special preparation) that are exclusively used for these high altitude destinations ?

Speedbird741
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Rj111
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RE: High Altitude Homebases

Mon Mar 09, 2009 11:45 pm

IB have cited the field performance of the A346 to be a reason behind their order. Obviously a lot of their destinations are at hot or high airports in the Andeas.

As others have mentioned AM and MX have used the DC-10-15 in the past.

I think you will generally find i higher MTOW accross the aircraft of these airlines, remember that every model is available in normally a variety of MOTWs.

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