ACA & DA/MDA

[lasseb]

I do appreciate the idea of the ACA as stated above and in the previous posts. I just don't get how you would find the actual value for a specific airplane, as no such figures are available in the POH.
Was it always 300 feet for all light twins?
But since its a CAPXXX thing, it's probably only known in UK land ��

[vetflyer]

Homsap

I agree thatfor AF447 automation seem greatly contributed to crash and as you say power attitude etc

Hopefully will never be in situation

Rgds

[Whopity]

I just don't get how you would find the actual value for a specific airplane,

It is a bit like a Personal VMC it is largely pilot dependent and is used specifically during training in light twins to allow for the reaction times of different pilots whilst practicing procedures. 300 ft was a typical value for VFR training however; by the time a pilot completed an IR then this conflicted with the DA, but by now the pilot should be sufficiently experienced not to need an additional height allowance above the DA.

On larger aircraft with closely adjacent engines Victor/ VC10 where a failure of one engine could easily impact on the adjacent engine, it was common to allow for the worst case of a double engine failure and a ACA was published. I recall spending 7 hours in a C130 conducting 2 engine DH trials where the published ACA was 600 ft. At max AUW we needed every inch of it.

[Cows getting bigger]

Someone asked about DA42 OEI baulked landings.



In this scenario, I tend towards Beagle's view on life. Furthermore, I'm not going to put any unnecessary drag into the equation until landing is assured.

[lasseb]

Thanks for posting it.. So the Diamond has such height. A bit high I must admit, but since I have never flown one I cannot decide if it is overkill or not.
Still have not seen in in a piper POH though.

[what next]

Originally Posted by lasseb

Still have not seen in in a piper POH though.

Me neither. And following this thread, I made a balked landing with a student a few days ago in the Seminole. From less than 50ft, with one engine set to the "zero thrust RPM" as per POH (which is supposed to be the same as a feathered propeller). I live to tell the story

[parkfell]

If the aircraft is STABLE at ACA/H for one engine landing (OEI), why now apply additional flap (normal two engine landing flap) requiring additional power, and retrimming. Running the risk of destabilising the approach?
Why not just keep the approach flap for the landing, and avoid increasing the workload at this critical stage?

Aircraft performance being the controlling factor in all discussions.

Just looking at the DA42 extract from COWS GETTIN BIGGER, a figure of 800' for the OEI decide point is remarkably high. Various combinations are then mentioned.....should you be flying a light twin in the first place with significant turbulence and windshear.
Notwithstanding the predicament you find yourself in, clearly a diversion is called for.

Anyone remember the Seneca 1 performance OEI.........now that was scary stuff !

[what next]

Originally Posted by parkfell

If the aircraft is STABLE at ACA/H for one engine landing (OEI), why now apply additional flap (normal two engine landing flap) requiring additional power, and retrimming. Running the risk of destabilising the approach?

That's certainly correct and this is also what is being taught and/or advocated for real engine out landings. At least where I fly and instruct. (Landing performance permitting of course).

But for training purposes the case of an engine failing at low level with the aircraft already fully configured for landing must also be mastered. In real life this is not entirely improbable because for example some types of engines are prone to rich cuts if the power is advanced too rapidly.

[parkfell]

So, you find yourself operating a type described by WHAT NEXT where a rich cut might be an issue.

I think that you need to mitigate the risk by appropriate briefings.
THREAT AND ERROR MANAGEMENT is taught from the outset of professional training.

So discuss the threat of a rich cut, and any other salient issues which might impact, and take the necessary measures to prevent it in the first place.

Historically of course I would refer to this as AIRMANSHIP, and say
DO NOT ADVANCE THE POWER RAPIDLY.
DO IT THE WAY YOU HAVE BEEN TAUGH, AND PRACTISED.

This is not the time to experiment. Leave that to the TPs.

[what next]

Hello!

Originally Posted by parkfell

I think that you need to mitigate the risk by appropriate briefings.
THREAT AND ERROR MANAGEMENT is taught from the outset of professional training.

Yes. But the rich cut is only one example of many why an engine might fail at the worst possible moment. You cannot brief every eventuality and our limited short time memory can not hold all the information anyway. And humans can react very emotive in certain conditions thereby forgetting almost everything they briefed before. When you are over the approach lights and another aircraft enters the runway or the aircraft shouts "windshear! windshear!" At them, 95 percent of pilots (including myself) will just push those levers forward and forget everything they ever knew about rich cuts. After that, the best chances will be with those who trained low-level go-arounds with and without engine failures.

[parkfell]

The 95% quoted seem to have a measure of panic if they really forgot when faced with a non normal event. Does not say a great deal about the quality of the training ??
The more you practice it, preferably in a simulator, the more of a non event it becomes: a matter of routine.
True you cannot brief everything. That is where experience, and good old fashioned AIRMANSHIP aka common sense is necessary.

I think the BA038 at LHR is a prime example. Retracted the flap setting by one position, some reduction in the drag, a very marginal impact on the Vref of the 777 and made it across the airfield boundary following double ENG FAIL on final due icing in the fuel system.

The contrast is the Turkish 737-800 into AMS with the failed no.1 RAD ALT (-4ft) and auto throttle in ARM on the approach. Unfortunately stalled on final and did not recover in time. CRM a critical factor.

One of the worse manoeuvres, in practice, is a normal two engine go-around. Not included in the LPC/OPC cycle, and a fairly rare event on the line. Once a year perhaps?
So to mitigate that, you brief your actions to initiate the G/A before briefing the plate/FMC glass.
Clear thought and preparation are but two ingredients to survival.