Max. acceleration height

[stancioiu]

In our RTOW tables we are given minimum and maximum acceleration height. I can't find what is the reason for a maximum acceleration height. Can you?
Brgds!

[captainpaddy]

The Maximum Acceleration height is the maximum height at which the acceleration phase can be completed using TOGA power while remaining within the 10 minute take-off power limit.

In other words, if you waited until the Max Accel height to accelerate you would, in theory, reduce to MCT power just as the 10 minute limit is reached.

[411A]

Standard acceleration height was 400 feet under CAR4b.
However, under 14CFR25 (originally) the acceleration height could be increased to up to 800 feet, depending on the certification standard chosen by the manufacturer.

Exception.
Some airfields require a higher acceleration height, and this can be provided by supplementary performance data, also provided by the manufacturer.

In all cases however, the engine max power time limitations must be observed.

[captainpaddy]

411A is referring to the regulatory requirements for the minimum acceleration height.

400 feet is a standard minimum regulatory accel height for most commercial transport aircraft, however it is not necessary that this height be adhered to.

For example at my operator we use 1500 feet as the standard minimum for all departures unless circumstances dictate the use of a higher minimum. This is for a medium jet. At my previous company we used 600 feet minimum for a medium turboprop.

The maximum acceleration height you asked about stancioui, has nothing whatsoever to do with the above.

[mutley320]

I think Capt. Paddy has it. It's the height you would reach in theory for that runway and that flap setting at max allowed temperature on one engine after 10 mins. (Airbus/JAA)
I believe it's something used by the performance engineers and has no real practical use in a day to day operation.

[john_tullamarine]

Another upper limit consideration .. if I recall correctly, the RR Dart had a feather pump limit which resulted in a 600 ft maximum third segment height.

[411A]

You do remember correctly JT, the feather pump limitation on the Dart certainly existed, on some aircraft.

Rolls Royce Dart, certainly the first successful civil gas turbine engine, and altho not all that fuel efficient by todays standards, it was truly a remarkably reliable engine.
Typical Rolls Royce, to be sure.

[BAe 146-100]

A certain Irish airline use 3000 plus airport elevation, for noise benefits.

BAe 146

[Rahul]

There are times I increase the acceleration height for departures which have say a straight ahead for 3000' and then a turn in the required direction to start my turn early and accelerate in the right direction. The engine out acceleration remains at default ( normally 1500' for the A320 ).
But, yes as far the reason for mac acceleration height goes, captain paddy has it bang on.

[mutt]

Airbus charts show a minimum acceleration height based on the airlines default value or obstacle clearance. And the maxiumum acceleration height based upon 5/10 takeoff thrust. BOTH OF THESE ARE BASED UPON AN ENGINE FAILURE.

The 1500 or 3000 feet profiles are generally noise abatement and are intended for ALL ENGINE operations


Mutt

[stancioiu]

Thanks for all replies! It seems that the 10 min time limitation is the reason for max acc. height. I checked several RTOW tables for different airports and the max acc height is around 3000 ft +/- max 100 ft.
Brgds

[Old Smokey]

Try doing some number crunching with engines where the manufacturers still haven't obtained an extension from 5 to 10 minutes after engine failure.

Much trickery can be involved when hills and other lumpy bits abound in great multitude! Particularly annoying to me was one "hilly" airport where the aircraft obstacle clearance performance was good, very good in fact, but it was necessary to impose an artificially steeper 2nd segment gradient to the higher than normal MAA to get there faster, reducing the 2nd segment time to leave enough of the 5 minutes for the 3rd segment.

Life wasn't meant to be easy:uhoh: (with apologies to Malcolm Fraser).

Regards,

Old Smokey