Minimum Acceleration Height

[Prop Job]

Good Day All,

The question I got is the following:

On the go-around from minima, on a Part 121 aircraft, what is the engine-inoperative minimum acceleration height?

Now, we always use 400' on our B190's and the performance manuals state the same, but I can't find it anywhere in the CAR's. I had a look in CAR 121.08.3, but I can't find anything there. Either that, or I need a new pair of specs more than I realise!

Any references to the regulations will be greatly appreciated!

Thanks,

Prop Job

[Intruder]

Depends on local (country and airline) procedures. While I have seen 400' used in several places (including FAR 25.111 and 25.121), we use 800' for our 747s.

[Prop Job]

Thanks Intruder.

We operate under South African CAR's.

If my understanding is correct, FAR 23/25 is only for airworthiness standards and not operating legislation, such as Part 91, 121 and 135. Basically how I understand it is in order to achieve the performance they achieved during certification, I need to follow the procedures laid down in FAR 23 or 25, whichever one applies.

The search continues...

Prop Job

[waren9]

Not sure there is one?

In this country, whatever it takes such that you can make good a net 2.5% climb gradient and make the missed approach altitude by the end of the procedure then that would be it.

[Prop Job]

waren9, I think you're right. It's the same with the South African Regulations.

121.8.8 Landing at destination and alternate aerodromes
-Landing weight must be within limits
-A missed approach from a landing where the decision heights are below 200 feet must allow for a gradient of 2.5%

I think the reason we use 400' is because that's what the manufacturer used during certification to achieve the required 2.5% climb gradient.

Prop Job

[411A]

I think the reason we use 400' is because that's what the manufacturer used during certification to achieve the required 2.5% climb gradient.



Nothing especially new, been that way for many years with most aircraft types under CAR4b, which preceeded 14CFR25.

The manufacturer determinds the accceleration height during flight testing...with a minimum of 400 feet.

[Northbeach]

Prop Job,

If I have misunderstood your question I apologize beforehand.
Given an engine failure, on the runway after V1, one is obligated to fly to the company mandated minimum acceleration height speed up, clean up achieve the “target speed” in the proper configuration and then climb to 1,500’ above the runway.
However, on the go around from a missed approach there is no requirement to level off anywhere other than the assigned missed approach altitude. On the go around from a missed approach there is no engine failure acceleration height.
In comparing the two scenarios; on the runway engine failure after V1 and loosing the engine on the approach or go around, you have more altitude and momentum in flight. I’m not aware of any profile on the missed approach that is going to have you level off at an intermediate altitude then clean up, prior to climbing to the missed approach altitude. This is why approach climb limits are important, if you are heavier than the approach climb limit for the conditions present you will not have the performance to achieve the required climb.
So I think the answer is there isn’t any minimum acceleration height on the go around from minimum for Part 121 Certified aircraft.

Respectfully,

Northbeach

[Intruder]

If my understanding is correct, FAR 23/25 is only for airworthiness standards and not operating legislation, such as Part 91, 121 and 135. Basically how I understand it is in order to achieve the performance they achieved during certification, I need to follow the procedures laid down in FAR 23 or 25, whichever one applies.
FAR 23/25 may be for certification standards, but those standards are designed to mesh with TERPS criteria, and airlines' OpSpecs are designed to provide operating criteria to meet AT LEAST the basic requirements.

If an airline's OpSpecs and training program are approved to meet higher criteria (e.g., the 800' min accel height instead of the 400' basic regulatory min), then you are obligated to operate in accordance with those rules and training. There should NEVER be a case where the OpSpecs or Training Manual has looser criteria than regulatory minimums, except if a specific waiver is in force.