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Topic: The 772LR 3% More Efficient Than The 772ER For LH
Username: YUL332LX
Posted 2004-08-06 21:37:44 and read 5807 times.

I just ran a simple regression with Boeing’s latest spec. and the 772LR comes out to be more than 3% more efficient than the ER for a route of 7730nm (772ER max. range). That means that at MTOW and typical conditions, the 772LR will use almost 1400Gal. less than the ER on a 7730nm flight.

Could airlines eventually consider this to be enough to offset the LR higher price compared to the ER?

Of course, we can’t expect Boeing to promote actively the 772LR over the 772ER but that might be another tool for Boeing against their key competitor. The LR version is clearly not going to sell in large quantities for ULH operations but this aircraft could fly «shorter» mission more efficiently than any other plane.

Any thoughts?


Topic: RE: The 772LR 3% More Efficient Than The 772ER For LH
Username: 5NEOO
Posted 2004-08-06 22:28:51 and read 5680 times.

I just ran a simple regression

I think you just answered your question with that statement.

Topic: RE: The 772LR 3% More Efficient Than The 772ER For LH
Username: SunriseValley
Posted 2004-08-06 22:46:48 and read 5622 times.


Do you have the data to run such an analysis on Airbus aircraft and other Boeing types ?

Topic: RE: The 772LR 3% More Efficient Than The 772ER For LH
Username: YUL332LX
Posted 2004-08-07 04:51:58 and read 5351 times.


A regression in itself is not an analysis. Numbers like range and fuel capacity are easily available and in our case, that’s all you need to make an adequate extrapolation by running a standard mathematical regression with fuel as the input and range as the output. And the result is: the LR will be more fuel-efficient than the ER for long haul.

It’s as simple as that! Now, is that enough to compensate the fact that the acquisition cost of the LR is higher than for the ER?

Topic: RE: The 772LR 3% More Efficient Than The 772ER For LH
Username: B2707SST
Posted 2004-08-07 05:41:10 and read 5276 times.

Are you using the stated fuel capacity of the plane (53,440 gallons) as your independent variable? That might lead to inaccurate results, because the fuel tanks may not be full at the quoted range. In fact, on the 772LR, they will not be full for a 7730nm flight with maximum payload. Even with full tanks, the aircraft must maintain certain reserves (in other words, in normal circumstances, it will not arrive with the tanks empty).

In order to control for all variables, we would need to compare fuel burn per hour at cruise altitude for two the aircraft at the same weight. To my knowledge, this information isn't publicly available.

However, according to a Boeing reference document provided by BCAInfoSys, one of our Boeing insiders, the direct operating costs per seat-mile for a 5,000 nmi trip are about 3% higher on a 772LR than on the 772ER. This may take landing fees into consideration, which are based on takeoff weight, but my guess is that the -200LR would burn more fuel because it is somewhat heavier. In the interests of full disclosure, the document is a few years old and does not take the recent 773ER/772LR performance improvements into account.

Of course, the 772LR has the advantage of a significantly larger payload than the -200ER on all routes. This may make it more profitable on shorter routes already flown by the -200ER.

Link to the Boeing reference guide:


Topic: RE: The 772LR 3% More Efficient Than The 772ER For LH
Username: YUL332LX
Posted 2004-08-07 18:17:10 and read 4927 times.


Thanks for your comments. I did use the latest 772LR spec. provided by Boeing but did not take into account the legal fuel reserve. My bad. However, we could make the working hypothesis that fuel reserves for the 772ER and 772LR would not be significantly different (unless fuel burn for 45 minutes at cruising altitude is significantly different between the ER and LR, which is what we are trying to figure out). Don't know how it would affect the results though. Of course, possible differences in landing fees are not included in this. Anyway, part of this could be solved by de-rating the engines when operating on shorter routes (i.e 7000nm flight)

However, the link you provided shows a range of 8800nm for the LR version while it is now over 9400nm for the same fuel capacity according to Boeing. Obviously, any operating costs based on shorter max. range would provide biased results.

The LR possible better fuel efficiency of the 772LR over the 772ER could essentially be explained by better engine efficiency and wingtips.


Topic: RE: The 772LR 3% More Efficient Than The 772ER For LH
Username: 7e7
Posted 2004-08-07 20:55:27 and read 4426 times.

A question that always wandered across my mind.

Another way of looking at it is:
'Could fuel burn alone justify the preference of one type over another?'
'Is potential offset from increased payload, over revenue cycles, (mainly in cargo) is it enough to justify the additional cost of LR?'

The answers are multi-faced; As there are many ways to look at it:
Notably, the acquiring cost (including engine selection), maintenance implications, and operations routes.

Although fuel burn is an important factor of the equations, investing in a lighter variety is the way most operators see it. From Boeing perspective, it is 'tailor' making the product to suit customers' (airlines) needs.

Let's take MH as an example, on their weight restricted DXB-EWR flight.
Going for LR seems logical, as of abolishing the need for DXB as a stop, and saving in landing costs, time, and fuel burn.
But what about the added purchase and maintenance cost?
This can be seen in flights to 'neighboring' HKG or BKK or even SIN that will cost more than just using ER's (although ER vs LR wasn't an immediate option when they first got their ER's)

Not in any way implying on A vs B or 2 vs 4, the Airbus' 4 holers burn more fuel than their counterparts (correct me if I'm wrong), yet you don't see every airilne avoiding A345's.

Topic: RE: The 772LR 3% More Efficient Than The 772ER For
Username: ACAfan
Posted 2004-08-07 21:13:27 and read 4356 times.


Could you put up the curves for us to see please!

At what distance does the LR efficiency cross over the ER efficiency?

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