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High Altitude Airports: 747-200 Better Than 744?  
User currently offlineMozart From Luxembourg, joined Aug 2003, 2239 posts, RR: 13
Posted (7 years 10 months 1 week 6 days 7 hours ago) and read 6180 times:

I remember LH flying to La Paz in the 1980s and maybe also at the beginning of the 90s with 747-200s, routing FRA-SJU-BOG-LIM-LPB. Thus, I know that 747-200s can make it to La Paz. La Paz is located at an altitude of 13,314 ft.

Somewhere else I read that the 747-400 cannot fly to or from La Paz.

That seems bizarre to me? The more modern, more powerful version cannot handle a high altitude airport?

Can anyone give me more details and explanations what could be behind this?'What is it that the 747-200 can do or has that the 744 doesn't?

Regards

Chris

6 replies: All unread, jump to last
 
User currently offlineRadimz From Czech Republic, joined Dec 2006, 8 posts, RR: 0
Reply 1, posted (7 years 10 months 1 week 6 days 5 hours ago) and read 6155 times:

I have just looked in the Boeing 747-400 Operations Manual and it is stated that the maximum take off and landing pressure altitud is 10000 feet, so it seems that a 744 cannot fly to or from La Paz. As Im not a pilot, Im not sure about reasons of that.

User currently offlineMozart From Luxembourg, joined Aug 2003, 2239 posts, RR: 13
Reply 2, posted (7 years 10 months 1 week 6 days 5 hours ago) and read 6149 times:

Radimz

Indeed, I was aware of that 10,000ft limit as well. However I wonder why the -200 could apparently do it, whereas the -400 is limited to 10,000ft?

Strange...


User currently offlineSCAT15F From United States of America, joined Feb 2007, 402 posts, RR: 0
Reply 3, posted (7 years 10 months 1 week 6 days 1 hour ago) and read 6085 times:

It could be that it is a function of the engines used and respective max TO weights, in that LH 747-400's have the lowest thrust versions of the RB211-524 and a MTOW of 875,000lb while the LH 747-200's with the 833,000lb MTOW might have the most powerful previous generation engine, which would be nearly equal in power to the former.

User currently offlineLTU932 From Germany, joined Jan 2006, 13864 posts, RR: 50
Reply 4, posted (7 years 10 months 1 week 6 days 1 hour ago) and read 6066 times:

Quoting SCAT15F (Reply 3):
It could be that it is a function of the engines used and respective max TO weights, in that LH 747-400's have the lowest thrust versions of the RB211-524 and a MTOW of 875,000lb while the LH 747-200's with the 833,000lb MTOW might have the most powerful previous generation engine, which would be nearly equal in power to the former.

LH uses the CF6-80 engine on all their 744s. On the 742s, they used the CF6-50.


User currently offlinePhilSquares From , joined Dec 1969, posts, RR:
Reply 5, posted (7 years 10 months 1 week 6 days ago) and read 6049 times:

Quoting Radimz (Reply 1):
I have just looked in the Boeing 747-400 Operations Manual and it is stated that the maximum take off and landing pressure altitud is 10000 feet, so it seems that a 744 cannot fly to or from La Paz. As Im not a pilot, Im not sure about reasons of that.

No one wanted the aircraft certified for operation above 10,000' MSL. The 747 Classic required additional certification to operate over 10,000' MSL. It's like buying additional weight in the certification process. It's just a matter of time and $$$!


User currently offlinePrebennorholm From Denmark, joined Mar 2000, 6548 posts, RR: 54
Reply 6, posted (7 years 10 months 1 week 5 days 20 hours ago) and read 5978 times:

We are talking a little "apples and oranges" here. "Can do" and "can do" can be two different things when we mix up physical and legal limitations.

Of course a 744 can physically be operated from La Paz.

Quoting SCAT15F (Reply 3):
It could be that it is a function of the engines used and respective max TO weights...

Neither the 742 nor the 744 can do La Paz at anything near max TO weights. They will both be very severely limited in fuel and payload capability. The limiting factor will most likely be wheel speed rather than RWY length.

For legal operation at La Paz the 744 would need to be certified for operation at such altitudes. That's a costly process involving a lot of test work which Boeing would probably do if that could sell some frames. If it doesn't sell planes, then it is waste of money.

Very likely rather simple calculations indicate that the 744 payload/range capability from La Paz would be so limited that such operation would hardly make sense. In any case it would very soon have to find a place to refuel. Then why not use a better suited plane for that first short leg on a flight. The 744 is simply the wrong plane for that place.

A 752 or 332 plane with the highest thrust engine option available would probably be able to lift a meaningful payload quite a bit further than a 744. Even if the 752 and 332 will also be limited way below Max TO weight.

Then why was the 742 certified for La Paz? Pure Guesswork: When that happened way back in last century, then the alternatives would be 707 or DC-8 instead of for instance 752 or 332. Planes which would have been even more severely limited than the 742.



Always keep your number of landings equal to your number of take-offs, Preben Norholm
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