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UA 777-200ER Mtow - Why?  
User currently offlineFlyDreamliner From United States of America, joined Jan 2006, 2759 posts, RR: 15
Posted (7 years 6 months 1 week 2 days 15 hours ago) and read 3818 times:

United Airlines' fleet of 777-200ER's (which is I believe, 38 strong) is currently rated to a MTOW of 648,000 lbs, as opposed to a max for the 772ER of 656,000lbs. This limits their range (so as to be shorter than that of their 744s). I'm wondering why UA ordered their 772ER's with this lower MTOW, and why they don't have it paper increased to 656,000? They are powered by Pratt and Whitney PW4090s, which aren't the most powerful variant on the 772ER, but could I believe support the 656,000 MTOW. Moreover, with its full range, the 772ER would be able to fly routes for UA more effectively than the 744 does.

The 772ER could bolster australia routes in summer, fly routes like IAD-KWI (as it has better cargo, fewer seats), as well as a number of other flights.

Anyone have any idea why my favorite airline doesn't have its 772ER's rated for full MTOW and full range? I enjoy their 772ER's much more than their 744s (if you've ridden their 744s, you understand).. and I'd love to see the 772ER fleet better used.


"Let the world change you, and you can change the world"
9 replies: All unread, jump to last
 
User currently offlineLTU932 From Germany, joined Jan 2006, 13864 posts, RR: 50
Reply 1, posted (7 years 6 months 1 week 2 days 15 hours ago) and read 3798 times:

I believe the reason why PW4090 powered 777s cannot be certificated for full MTOW is because of emmision problems of the engines, which is why they are derated to something like 84,000 lbs. Correct me if I'm wrong though.

User currently offlineLaxintl From United States of America, joined May 2000, 25387 posts, RR: 49
Reply 2, posted (7 years 6 months 1 week 2 days 14 hours ago) and read 3744 times:

Actually the United 777 XI & XP version MTOW is 640,000lbs, while their domestic 2 class XA and early version XC are all 545,000lbs.

While I suppose UA could indeed purchase weights up to 648,000lbs on the XI and XP's as previously mentioned the PW4090 is performance limited so, it would be impossible currently to jump all the way to 656,000lbs.

Btw - I show the total current 777 fleet at 52 examples.
6 - XA
13-XC
18-XI
15-XP



From the desert to the sea, to all of Southern California
User currently offlineFlyDreamliner From United States of America, joined Jan 2006, 2759 posts, RR: 15
Reply 3, posted (7 years 6 months 1 week 2 days 14 hours ago) and read 3701 times:

The performance issue with their engines is extremely disappointing... I knew PW4098 had issues but I had no idea PW4090 had as bad of issues... too bad UA is so faithful to PW.. both the RR Trent and GE90 options on 772ER appear much better.

Any idea why they don't buy the MTOW upgrage from 640,000 to 648,000?



"Let the world change you, and you can change the world"
User currently offlineLTU932 From Germany, joined Jan 2006, 13864 posts, RR: 50
Reply 4, posted (7 years 6 months 1 week 2 days 14 hours ago) and read 3656 times:

Quoting FlyDreamliner (Thread starter):
The 772ER could bolster australia routes in summer, fly routes like IAD-KWI (as it has better cargo, fewer seats), as well as a number of other flights.

Wasn't UA already operating IAD-KWI with T7s?

Quoting FlyDreamliner (Reply 3):
Any idea why they don't buy the MTOW upgrage from 640,000 to 648,000?

Perhaps they just don't need to at the moment.


User currently offlineFlyDreamliner From United States of America, joined Jan 2006, 2759 posts, RR: 15
Reply 5, posted (7 years 6 months 1 week 2 days 14 hours ago) and read 3645 times:

Quoting LTU932 (Reply 4):
Quoting FlyDreamliner (Thread starter):
The 772ER could bolster australia routes in summer, fly routes like IAD-KWI (as it has better cargo, fewer seats), as well as a number of other flights.

Wasn't UA already operating IAD-KWI with T7s?

Unless I am mistaken, the 744 operates that route.



"Let the world change you, and you can change the world"
User currently offlinePlanecrazy2 From United States of America, joined Apr 2004, 615 posts, RR: 4
Reply 6, posted (7 years 6 months 1 week 2 days 13 hours ago) and read 3636 times:

Quoting FlyDreamliner (Reply 5):
Unless I am mistaken, the 744 operates that route.

You are, it operates with a 777.



United Airlines - Worldwide Service
User currently offlineFlyDreamliner From United States of America, joined Jan 2006, 2759 posts, RR: 15
Reply 7, posted (7 years 6 months 1 week 2 days 13 hours ago) and read 3619 times:

sorry, my mistake. I wonder why I thought it was on a 747-400.. how strange of me.

thanks for the correction.



"Let the world change you, and you can change the world"
User currently offlineLaxintl From United States of America, joined May 2000, 25387 posts, RR: 49
Reply 8, posted (7 years 6 months 1 week 2 days 13 hours ago) and read 3615 times:

Purchasing higher weights for the sake of simply having it is likely not the best of a business decision.

The question is more would the higher weight pay for themselves? Remember besides upgrade cost, there are other continuous operating cost factors aswell. For instance in many countries over flight fees and landing charges are based on an aircraft MTOW. So in other words flying around with a higher gross aircraft will cost you more money whether the added weight ever generates additional revenues. Somewhat like folks purchasing a 4 x 4 vehicle and never in their lives make use of it. Its actually quite common (esp in Europe) to purchase the lowest weight aircraft that can do the required mission - look at the 744 "lite" aircraft which both BA and Virgin operate. No point in paying for something that is unlikely to be used, while costing you extra daily.

It could very well be that UA manages OK with its current 777s, and the few routes that could likely use the slight boost to produce extra revenues simply dont adequately offset the additional cost involved.

And yes, IAD-KWI is operated with a 777.



From the desert to the sea, to all of Southern California
User currently offlineBrendows From Norway, joined Apr 2006, 1020 posts, RR: 4
Reply 9, posted (7 years 6 months 1 week 2 days 12 hours ago) and read 3552 times:

Quoting LTU932 (Reply 1):
I believe the reason why PW4090 powered 777s cannot be certificated for full MTOW is because of emmision problems of the engines, which is why they are derated to something like 84,000 lbs. Correct me if I'm wrong though.

You are (except from the thrust rating) completely correct LTU932 checkmark  This is what Lightsaber had to say about this almost two years ago:

Quoting Lightsaber (Reply 13):
The reason for the pw4090 thrust limit is simple: Emissions. The pw4090 at 90,000lbf of thrust puts out 99.2% of the allowed ICAO NOx emissions. This is the highest certified thrust that Pratt is allowed to sell on the market. You are not allowed to fly into/out of a FAA or JAA airport without meeting ICAO emissions. In other words, the pw4090 is certified for 91,700lbf of thrust in every criteria *except* emissions. But you're not allowed to miss even one certification criteria...

(can be found in this thread: More PW4090 Questions (by ConcordeBoy May 24 2005 in Tech Ops))


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