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A330 Derated Climb

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A330 Derated Climb

Old 18th Apr 2017, 07:52
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A330 Derated Climb

Hi guys,

I was wondering what are your airlines' policies regarding the usage of DCLB on the A333.

Ours don't use it at all, even when the plane is light (and it often is, as we do lots of shorthaul).

Also, any materials on cost/benefit of DCLB?
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Old 18th Apr 2017, 09:45
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We pretty much use it all the time even at MTOW. Remove the derate in the climb if necessary otherwise just leave it managed to sort itself out if no level restrictions. DCLB will use slightly more fuel than just using normal climb power however there are savings to be had in engine wear. I guess our company is happy to burn a bit more to save the engine life. No figures on how much extra it burns but in the grand scheme of things it would be minimal
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Old 18th Apr 2017, 10:11
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We used to use DCLB on company 332 Trents but am aware of another company using P&W engines on 332 and 333s who do not.
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Old 18th Apr 2017, 10:23
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Our birds are CF6-powered and they seem to be sluggish climbers even at Max CLB thrust. At least in comparison to the 320 I flew before...

How much lower ROC can one expect with DCLB 1 and 2 and what's the fuel penalty?
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Old 24th Apr 2017, 13:36
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My company which uses RR Trent's on Power by the Hour uses Derate2 climb for all operations on both A332 and A333.
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Old 25th Apr 2017, 02:07
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Yes unless you have a requiremt to reach TOC by a certain point and 285 kts doesn't cut it.
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Old 28th Apr 2017, 02:05
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It's a tradeoff, fuel vs engine maint cost. To me (an old engine guy) it makes little sense to thrash those donks when it might save you a minute or two reaching TOC.

But a disciplined airline should have powerplant and ops engineers meeting with management, reviewing warranty/guarantee restrictions, sliding-scale maint. costs, current fuel prices, TOGWs, and deciding what's best for each route for the airline.
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Old 28th Apr 2017, 07:59
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In a disciplined airline - yes. However, I have an uneasy feeling deep inside, that in the mob I work for, it was decided far less scientifically...

As is side note, I heard an story, that in one airline, when their first 330's were introduced, they were merrily flying using Max CLB for around a year - until RR sent them 1million $ bill
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Old 28th Apr 2017, 13:27
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There have been 1 or 2 past PPRuNe threads commenting that after a reduced ATM takeoff, selecting CLB may result in a throttle push. Yes, and TOC at rated CLB may well be harder on the engine than the takeoff rating. After a while you get used to it and drive on.

On the plus side: From an engineer's perspective, think of the takeoff as a warm-up setting before going to a higher setting.
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Old 29th Apr 2017, 10:03
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Originally Posted by divinehover View Post
My company which uses RR Trent's on Power by the Hour uses Derate2 climb for all operations on both A332 and A333.
In fact we also do Derate 2 climbs with our A340-600 fleet as well.
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Old 19th May 2017, 07:40
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Effect on ATC

These derated climbs are a headache for ATC. A330's generally want to be up at FL350 to FL390 straight off the deck, but the slow climb rate means that they are in the way of all the other aircraft for a longer period. This may well mean you get interrupted climbs with stop offs at intermediate levels. Planning your climb by the controller is much more difficult as predicting your level at a crossing point with other routes is hard to judge. To be honest it's like watching an L1011 in the old days except they didn't climb so high.
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Old 19th May 2017, 13:03
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QR calculated it is cheaper not to use derate, only used to optimize take off on wet rwy
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Old 20th May 2017, 00:05
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I won't quarrel about takeoff fuel savings, but that's not the only piece of the cost pie. If there's a fuel burn deterioration guarantee from the OEM, derate (or ATM) is taken into account in any settlement of cruise fuel burn payout.
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Old 20th May 2017, 02:00
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Unless you are super heavy , what's the harm starting off with D2? Then D1? If the math is really not working out fit your climb requirement cancel debate select speed early enough and things should be good!
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Old 20th May 2017, 21:43
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From another aspect,
Derated climb eases pilot's hand as preventing higher rate of climb at departure with many level offs, especially with light weight take off from a busy airport.
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