The 77W obviously is far more capable and economical for long-haul but I was curious about which would make more sense for medium haul distances like ME-India. I can't see an obvious answer as the 773 is lighter while the 77W has the more efficient GE-90-115B.

*Bump*

I'd be interested to see a real numbers comparison too, if anyone has one.

Its an interesting and time relevant question. There are a plethora of 777 themed questions this (northern hemisphere) winter.

hypothesis: the 773 is an under-appreciated frame. South-east Asian and Russian LLCs or leisure carriers will opportunistically consider these frames. They likely represent a better risk adjusted opportunity than used A380 for short-medium high density routes.

Alternatively the 77W poses a conundrum for lessees. It is currently one of the most capable heavy metal frames. Releasing a mid-life 77W gives your competitors availability for the frame at used economics.

NZ use the 77W on 3-4 hour journeys between Australia and New Zealand (AKL-BNE,SYD,MEL), they use them in what would of been the aircraft downtime between long-haul services each day. So effecitivitly offsetting additional operating costs, by reducing the need for addtional aircarft.

CX 'misuses' 77Ws on its short haul network but more as something to do for the aircraft instead of sitting on the ground between longhauls. We also have a fleet of very hard working 773s. In our configs, the 77W carried either 275 or 340 whereas our 773s carry 398 pax and burn less fuel doing it. I dont have figures at hand but it is obviously a complicated mix of direct operating costs, lease costs, pax yield, aircraft usage etc..

CX Flyboy wrote:

CX 'misuses' 77Ws on its short haul network but more as something to do for the aircraft instead of sitting on the ground between longhauls. We also have a fleet of very hard working 773s. In our configs, the 77W carried either 275 or 340 whereas our 773s carry 398 pax and burn less fuel doing it. I dont have figures at hand but it is obviously a complicated mix of direct operating costs, lease costs, pax yield, aircraft usage etc..

How much less fuel? For your airline? City pairs too if you can.

They would be deployed on mainly regional routes like HKG-TPE/KIX/HND/CTS/BKK/SIN

Not that easy to make an assessment on the fuel use between them as they are configured very differently the 773 can have 150 more seats installed than the 77W.

Cost of ownership will be lower on the 773.

Overall cost per seat would be lower on the 773 if you had just bought/leased the 77W for regionals, however the reason the 77W has fewer seats is it is bought/leases configured for long haul and it’s just the opportunity cost to operate them regionally.

jagraham wrote:

CX Flyboy wrote:

CX 'misuses' 77Ws on its short haul network but more as something to do for the aircraft instead of sitting on the ground between longhauls. We also have a fleet of very hard working 773s. In our configs, the 77W carried either 275 or 340 whereas our 773s carry 398 pax and burn less fuel doing it. I dont have figures at hand but it is obviously a complicated mix of direct operating costs, lease costs, pax yield, aircraft usage etc..

How much less fuel? For your airline? City pairs too if you can.

Sorry I think my management would frown upon sharing of such data in public.

Of note is that CX's regional 773s are low weight variants with derated RR Trents. Their MTOW is around 263T and the engines are derated to 84Klbs IIRC (vs. 300T and 98Klbs respectively for the base -300).

I'm not sure what other operators use these lower weight 'regional' -300. I'm guessing other classic operators around Asia (about the only place where they make sense)?

jagraham wrote:

How much less fuel? For your airline? City pairs too if you can.

What you are asking is a bit unfair in terms of expecting an employee to divulge how much an airline is burning over a city pair. I have put together some generic numbers below, these are from interpolation of data not found in our company manuals but elsewhere. This has been done for close enough to the same payload for both aircraft (around 50 tonnes), the OEW was taken from the ACAPS.

For a 777-300 with PW4090 engines to FAA rules, this is based upon an OEW of 351700 lb from the ACAPS and a payload of 110210 lbs, giving a landing weight of 461910 lb with a 310/0.84 climb, LRC, 0.84/310/250 descent with 4000 ft step climbs above optimum altitude

Trip (nm) Fuel (x1000 lb)
1000 35.3
1500 51.5
2000 68.1
2500 85.1
3000 102.6
3500 120.7
4000 139.2
4500 158.3
5000 178.0


For a 77W with GE90-115BL engines to FAA rules, this is based upon an OEW of 370000 lb from the ACAPS and a payload of 11000 lbs, giving a landing weight of 480000 lb with a 310/0.84 climb, LRC, 0.84/310/250 descent with 4000 ft step climbs above optimum altitude

Trip (nm) Fuel (x1000 lb)
1000 34.6
1500 50.2
2000 66.1
2500 82.7
3000 99.9
3500 117.5
4000 135.4
4500 153.8
5000 172.5

This is only one part of the total operating cost, it shows that the 77W will burn 2-3% less fuel than the 777-300 with the PW4070. However I think the ownership and maintenance costs would be much lower on the 777-300, making it the overall winner.

Disclaimer, I didn't actually check if any limits were exceeded above, some of these scenarios may not be possible.

Great data. Was the 77W payload 110000lbs rather than the 11000lbs as shown?

Yes both about 50 tonnes

zeke wrote:

jagraham wrote:

How much less fuel? For your airline? City pairs too if you can.

What you are asking is a bit unfair in terms of expecting an employee to divulge how much an airline is burning over a city pair. I have put together some generic numbers below, these are from interpolation of data not found in our company manuals but elsewhere. This has been done for close enough to the same payload for both aircraft (around 50 tonnes), the OEW was taken from the ACAPS.

For a 777-300 with PW4090 engines to FAA rules, this is based upon an OEW of 351700 lb from the ACAPS and a payload of 110210 lbs, giving a landing weight of 461910 lb with a 310/0.84 climb, LRC, 0.84/310/250 descent with 4000 ft step climbs above optimum altitude

Trip (nm) Fuel (x1000 lb)
1000 35.3
1500 51.5
2000 68.1
2500 85.1
3000 102.6
3500 120.7
4000 139.2
4500 158.3
5000 178.0


For a 77W with GE90-115BL engines to FAA rules, this is based upon an OEW of 370000 lb from the ACAPS and a payload of 11000 lbs, giving a landing weight of 480000 lb with a 310/0.84 climb, LRC, 0.84/310/250 descent with 4000 ft step climbs above optimum altitude

Trip (nm) Fuel (x1000 lb)
1000 34.6
1500 50.2
2000 66.1
2500 82.7
3000 99.9
3500 117.5
4000 135.4
4500 153.8
5000 172.5

This is only one part of the total operating cost, it shows that the 77W will burn 2-3% less fuel than the 777-300 with the PW4070. However I think the ownership and maintenance costs would be much lower on the 777-300, making it the overall winner.

Disclaimer, I didn't actually check if any limits were exceeded above, some of these scenarios may not be possible.

Thanks for the info - this is the type of thing I was looking for.

I see that the 77W is more efficient than the 773 for all stages. I was expecting something more like the A330 / A350 lineup, where the least fuel burn under 2 hours is an A333 (haven't been able to determine engine type), then for 2 to 4 hours, the A339, then the A359 over 4 hours (I have lots of questions about this too, but that's for another topic). Any insight as to why the 77W is better than the 773 on short lengths? And why the difference - for about the same TOW - is so small??

Thanks again!

Stitch wrote:

jagraham wrote:

Any insight as to why the 77W is better than the 773 on short lengths? And why the difference - for about the same TOW - is so small??

The GE90-115B is more fuel-and propulsive-efficient than the PW4090. The 77W also entered service with better aerodynamics than the 773 (some of which are retrofittable to the 773 via a PiP) and the 77W received another engine and aerodynamic PiP in 2016.

I agree with all you said. However, zeke's numbers show a 2% to 3% advantage for the 77W. I would have expected better, especially as the stage length increased.

It would appear that the main advantage of the 77W over the 773 is that the 77W flies farther with no penalty at any stage length. 2% to 3% on fuel burn is good, but not enough to ditch a paid for 773 for a 77W. What am I missing?

jagraham wrote:

.
It would appear that the main advantage of the 77W over the 773 is that the 77W flies farther with no penalty at any stage length. 2% to 3% on fuel burn is good, but not enough to ditch a paid for 773 for a 77W. What am I missing?

The 77W is used as a long haul aircraft, like all aircraft it is subject to payload limitations. So generally the aircraft will be configured with 1-200 seats less than a regional 773. The comparison I made was based upon carrying the same payload, around 50 tonnes. With the reduced seat count on the 77W you would have to carry a lot more cargo than a 773, in reality this is not the case. Regionally a 77W does not carry much more revenue payload than a 330, similar seat capacity as a long haul 77W and carries the same amount of cargo.

The disclaimer I put above I said I did not check to see if limits were exceeded, the MTOW of the 773 with those engines is between 560,000 and 660,000 lb. I will let you work out which ones I could not do.

On a total cost and total revenue basis, I would think regionally the 773 would be the clear winner over the 77W. The minor fuel burn difference is minor in the total cost when maintenance and ownership costs are taken into account. Being lighter the 773 also is charged less for enroute and airport charges. The 773 with more seats installed would generally be able to generate more revenue.

zeke wrote:

jagraham wrote:

.
It would appear that the main advantage of the 77W over the 773 is that the 77W flies farther with no penalty at any stage length. 2% to 3% on fuel burn is good, but not enough to ditch a paid for 773 for a 77W. What am I missing?

The 77W is used as a long haul aircraft, like all aircraft it is subject to payload limitations. So generally the aircraft will be configured with 1-200 seats less than a regional 773. The comparison I made was based upon carrying the same payload, around 50 tonnes. With the reduced seat count on the 77W you would have to carry a lot more cargo than a 773, in reality this is not the case. Regionally a 77W does not carry much more revenue payload than a 330, similar seat capacity as a long haul 77W and carries the same amount of cargo.

The disclaimer I put above I said I did not check to see if limits were exceeded, the MTOW of the 773 with those engines is between 560,000 and 660,000 lb. I will let you work out which ones I could not do.

On a total cost and total revenue basis, I would think regionally the 773 would be the clear winner over the 77W. The minor fuel burn difference is minor in the total cost when maintenance and ownership costs are taken into account. Being lighter the 773 also is charged less for enroute and airport charges. The 773 with more seats installed would generally be able to generate more revenue.

The actual aircraft efficiency - as opposed to the configuration which generates maximum revenue - is best determined by as close to an apples-to-apples comparison as you can get. Which is what you did. Thank you very much.