High & Hot: 787 vs A350? (2024)

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jhsusman

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Tue Jul 09, 2024 1:02 pm

Anyone know how the 787 and A350 compare in high and hot performance?

I know that TK is using an A350-900 for its new DEN-IST flights although the eastbound departure time is around 7:30pm. Not sure why they picked the A350 over the slightly smaller 787-9 to start this new route but maybe high and hot performance contributed to their decision. . .

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gloom
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Tue Jul 09, 2024 1:17 pm

Indeed, this could be an argument for 359. Quick look on public data reveals at ISA+15, 4km runway at 6000ft the data published is 228t on 789 (-26t on MTOW 254t), and 261t on 359 (-19t on MTOW 280t, I assume Turkish gets 280t birds; if they're 283t, it's -22t).
However, I have some doubts. Air distance between the two is around 5500nm (5350nm straight line), so it would have to be both fuel and payload heavy to be the argument. I'm not quite sure 5500nm is the distance where it would make a difference.

Cheers,
Adam

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bosflyer12746
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Tue Jul 09, 2024 1:23 pm

I don’t know how they decide between them, but Boston and DC both get the 359 as well and certainly are NOT hot and high airports…SFO even gets a mix of both the 359 and 789. I can’t imagine the hot and high component is a particularly important factor here

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sxf24
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Tue Jul 09, 2024 1:30 pm

I think a better example is to look at ADD and see how ET uses its fleets.

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A220HubandSpoke
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Tue Jul 09, 2024 1:37 pm

Specifically the A35K doesn't perform that well in harsher desert conditions.

Don't believe me? Sir Tim Clark of Emirates said so.

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Clydenairways
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Tue Jul 09, 2024 1:39 pm

Both seem to be good performers if you look around at the various hot and high airports, both have a good mix of 787 and A359.

scbriml
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Tue Jul 09, 2024 1:42 pm

A220HubandSpoke wrote:

Specifically the A35K doesn't perform that well in harsher desert conditions.

Don't believe me? Sir Tim Clark of Emirates said so.

Yet both EY and QR operate the A35K in identical conditions. High & Hot: 787 vs A350? (8)

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JerseyFlyer
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Tue Jul 09, 2024 1:42 pm

A220HubandSpoke wrote:

Specifically the A35K doesn't perform that well in harsher desert conditions.

Don't believe me? Sir Tim Clark of Emirates said so.

That's about engine degradation until RR implement fixes that are in the pipeline

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phatfarmlines
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Tue Jul 09, 2024 1:46 pm

sxf24 wrote:

I think a better example is to look at ADD and see how ET uses its fleets.

And they still have to make westbound fuel stops.

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DartHerald
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Tue Jul 09, 2024 1:50 pm

A220HubandSpoke wrote:

Specifically the A35K doesn't perform that well in harsher desert conditions.

Don't believe me? Sir Tim Clark of Emirates said so.

Although his airline doesn't have any to be able to make its own direct comparison!

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jfk777
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Tue Jul 09, 2024 2:21 pm

Avianca uses 787-8 from BOG to Europe.

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MIflyer12
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Tue Jul 09, 2024 2:32 pm

Gloom is on the right path.

DEN isn't going to be runway length-limited at 16000 ft, although I suppose it could be tire speed limited.

Pull out the OEM payload range charts and adjust for temp and elevation. The differences are going to be pretty marginal and may be lost in the noise of differences in seating density and 275T/280T/283T A359 configs.

And, you, know, it may not be hot/high performance at all: it could be wish for higher seat count or aircraft utilization that is a deciding factor.

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caverunner17
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Tue Jul 09, 2024 5:23 pm

gloom wrote:

Indeed, this could be an argument for 359. Quick look on public data reveals at ISA+15, 4km runway at 6000ft the data published is 228t on 789 (-26t on MTOW 254t), and 261t on 359 (-19t on MTOW 280t, I assume Turkish gets 280t birds; if they're 283t, it's -22t).
However, I have some doubts. Air distance between the two is around 5500nm (5350nm straight line), so it would have to be both fuel and payload heavy to be the argument. I'm not quite sure 5500nm is the distance where it would make a difference.

Cheers,
Adam

So if I'm reading the charts correct, at +15C, the A359 should be around 266-268 since DEN has a 6.4KM runway.

Even if you go to 265T, how far (distance) on a realistic configuration of an A359 does that get you with a usable payload? 7000 miles? 7500 miles?

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N1120A
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Tue Jul 09, 2024 5:29 pm

Both the 787 and A350, especially the 359 and the first two 787 models, are pretty incredible performers. BA's MSY-LHR on the 788 regularly uses the shorter runway at MSY. Also, AM has an entirely 787 based long haul fleet now - and they face some of the toughest conditions for takeoff performance on earth.

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crimsonchin
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Tue Jul 09, 2024 5:54 pm

A220HubandSpoke wrote:

Specifically the A35K doesn't perform that well in harsher desert conditions.

Don't believe me? Sir Tim Clark of Emirates said so.

If you could provide evidence for this? Because I'm almost certain you are misinterpreting what he was talking about.

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T54A
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Tue Jul 09, 2024 5:57 pm

This is an irrelevant question without specific conditions and payload data. Both were certified under the same rules.

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gloom
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Tue Jul 09, 2024 7:48 pm

caverunner17 wrote:

So if I'm reading the charts correct, at +15C, the A359 should be around 266-268 since DEN has a 6.4KM runway.

Notice it's ISA +15, not +15degs C. ISA is a standard atmosphere. So ISA+15 at 6000ft is 15 deg more than usually at 6000ft. I could've tried my memory, but used google instead, we're talking 18degs at 6000ft.
See:

https://www.digitaldutch.com/atmoscalc/

I assume you checked the charts properly, don't really have a time to check now.

caverunner17 wrote:

Even if you go to 265T, how far (distance) on a realistic configuration of an A359 does that get you with a usable payload? 7000 miles? 7500 miles?

What is usable payload? I believe A359 at first weight (268T) was advertised as 7400? 7600? All of this at full board (pax+bags, around 300 pax). So your guess is pretty much right. Above 7000 nautic miles, certainly. Newer batches would go further, since the frames are now lighter and are more effective (engine improvements, frame improvements). This is worth a few more tons of load for same range.

Cheers,
Adam

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caverunner17
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Tue Jul 09, 2024 9:02 pm

gloom wrote:
caverunner17 wrote:

So if I'm reading the charts correct, at +15C, the A359 should be around 266-268 since DEN has a 6.4KM runway.

Notice it's ISA +15, not +15degs C. ISA is a standard atmosphere. So ISA+15 at 6000ft is 15 deg more than usually at 6000ft. I could've tried my memory, but used google instead, we're talking 18degs at 6000ft.
See:

https://www.digitaldutch.com/atmoscalc/

I assume you checked the charts properly, don't really have a time to check now.

caverunner17 wrote:

Even if you go to 265T, how far (distance) on a realistic configuration of an A359 does that get you with a usable payload? 7000 miles? 7500 miles?

What is usable payload? I believe A359 at first weight (268T) was advertised as 7400? 7600? All of this at full board (pax+bags, around 300 pax). So your guess is pretty much right. Above 7000 nautic miles, certainly. Newer batches would go further, since the frames are now lighter and are more effective (engine improvements, frame improvements). This is worth a few more tons of load for same range.

Cheers,
Adam

Makes sense. I did the initial math wrong on the runway - it's just under 4.9km, but it seems like the Airbus chart maxes out at 5km anyways.

Good call on the initial 268T variant. Seems like that was advertised at just under 8000nm, so 7000nm is a conservative possibility.

http://www.gcmap.com/mapui?R=7000nm%40den

That certainly would open up options with the ME3, along with all of China, Hong Kong, Tiawan, Auckland, etc.

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zeke
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Wed Jul 10, 2024 7:33 am

caverunner17 wrote:

So if I'm reading the charts correct, at +15C, the A359 should be around 266-268 since DEN has a 6.4KM runway.

Even if you go to 265T, how far (distance) on a realistic configuration of an A359 does that get you with a usable payload? 7000 miles? 7500 miles?

I ran this through the performance program, it will do 273 tonnes out of 16R, 20 deg C (just above ISA+15), QNH 1013, nil wind dry.

The limit is brake energy, the V1 ground speed is still fairly low at this weight (165 kts), 40 kts below the tyre speed limit.

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zeke
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Wed Jul 10, 2024 7:36 am

jhsusman wrote:

maybe high and hot performance contributed to their decision. . .

They will put the respective frames where they make the most money from them. Each of them will have a profile of what mix of passengers and cargo they expect.

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High & Hot: 787 vs A350? (2024)
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