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B732 Climb Out Of CDG.  
User currently offlineSOU146 From United Kingdom, joined Jun 2004, 53 posts, RR: 0
Posted (9 years 9 months 3 weeks 15 hours ago) and read 1669 times:

On Wednesday I flew BOH - CDG - BOH on a specially charted day trip onboard an EAF B732 (I shall shortly be writing a trip report).

On take off from CDG, the take off roll was normal and so was rotation. After no less then a minute from leaving the tarmac the captain throttled back the engines and the angle of climb reduced. We then seemed to quietly climp into the air. At the time I didn't really think much of it as I was fixated by the Eiffel Tower and the lights of Paris illuminated below us. But have today been looking at photos taking at CDG and there are very, very few of B732 in recent times. I know they are fast disappearing from our skys and very few operators use them anymore but this got me thinking that perhaps the reasons the engines we're throttled back to the extent they we're was to do with new regulations on older aircraft with noisy engines. We took off at about 23.15, and when I booked the trip a few months ago, we we're supposed to be flying into Pontoise but due to 'operational reasons' we had to use CDG.

This may be totally normal practise as this was my first time flying out of CDG but I'd thought I'd ask the question anyway.

Does anybody know of any restrictions with regard to older aircarft equiped with noisy engines using Fench airports....?

Thanks in advance.

1 replies: All unread, jump to last
 
User currently offlineSpacecadet From United States of America, joined Sep 2001, 3607 posts, RR: 12
Reply 1, posted (9 years 9 months 3 weeks 14 hours ago) and read 1554 times:

On take off from CDG, the take off roll was normal and so was rotation. After no less then a minute from leaving the tarmac the captain throttled back the engines and the angle of climb reduced. We then seemed to quietly climp into the air.

Normal climb profile for almost any modern airliner (in fact I'm just hedging by saying that; I personally know of no airliner flying today where this is not standard procedure).

Takeoff thrust and climb thrust are two different things. Takeoff thrust is intended to speed up the plane as quickly as possible given the confines of the runway, in order for the plane to get off the ground within a reasonable safety margin. Takeoff thrust, however (even in de-rated takeoffs), is not at all efficient - it eats up fuel and is more power than you need anyway for a comfortable climb. (At a normal rate of climb, you'd overspeed pretty quickly using takeoff thrust.)

A lot of things can affect exactly what the optimal takeoff and climb thrust settings are. On some days and on some runways, the difference may be small enough that you might not notice the reduction to climb thrust. Most of the time, though, you'd notice it. You may not have noticed it on previous flights because of where you were sitting, or if you normally fly on airplanes with quieter engines, or whatever. (You'd still usually feel it, though; it usually feels like you're in a car where the driver suddenly hits the brakes.)

Does anybody know of any restrictions with regard to older aircarft equiped with noisy engines using Fench airports....?

If this was a noise abatement takeoff, exactly the opposite would likely have occured.

In a noise abatement takeoff, a series of procedures are used both to avoid residential areas and to climb as quickly as possible (the higher the airplane is, the less noise you hear on the ground). So an airplane will stay at takeoff thrust longer, and the reduction to climb thrust will be less dramatic. Some airplanes are capable of climbing more quickly than others, though, and some engines are rated for running at high pressure ratios longer than others, so not every noise abatement takeoff is going to feel the same. Yours definitely sounds like the opposite of what you'd want to do in a noise abatement takeoff, though.

Obviously, airlines hate noise abatement takeoffs and avoid them whenever possible. They waste fuel and are also harder on the engines.

Noise abatement takeoffs are common in many areas. But this sure doesn't sound like one. Just sounds like a normal takeoff, where the reduction to climb thrust was more noticeable than usual in an airplane with louder engines than most.

btw, with climb thrust you're not actually climbing any slower than you are at takeoff using takeoff thrust, because your airplane is going a lot faster than it was at takeoff.



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