how about going to a runway where it is possible to land ahead!
a twin rating is not just valid for the home airfield.

i did say showing the student, not letting them do it

hugh_flung_dung,

The way you & I teach is very similar!

You mention (point 2.) the below Vtoss, below ACH and the above Vtoss, above ACH cases - what about above the one and below the other? It gets complicated, which is not what one looks for in an emergency brief.

For this reason, I teach the same as you do, but without any discussion on heights. One is either at/above a safe speed or one is not. (This assumes a typical take-off profile where reaching a particular speed occurs at a similar height for all take-offs.)


Regarding EFATO, land back on:
Given h_f_d's numbers look broadly correct, I don't instruct near any 2400m runways where GA training is permitted. Could do it in the instrument ground trainer though...

O8

Above and below Vtoss I can understand. But the concept of ACH applying on departure above Vtoss escapes me. The a/c is already effectively in the 'go-around' configuration and is hardly in the process of landing!

KISS would seem to apply here?

Why not just operate the a/c such that, once above Vtoss an engine failure at any stage of flight will not prove critical. Use such speeds and configurations as will enable level flight at least in the event of the failure of the most critical engine. Fly the approach (with both engines operating) in such a configuration that it may safely be continued following failure of the most critical engine (might require some demanding power, drag, trim and fancy footwork following a failure when close to Vmca in the landing configuration?) - and subsequently only configure fully for landing when at ACH on one?

BEAGS: I didn't explain it too well.
In practise, from a failure at Vtoss in a Seneca 1, the average stude cannot get through the drills and start to climb without descending 100-150ft, even at training weights. Because of this I add a height to the go/nogo decision; historically I've used 200ft.
As I wrote my earlier mammoth offering it dawned on me that it would be easier for the stude to have one height gate to deal with - following the KISS principle let's call it Ach. Engine failure below Ach, whether taking off or landing, leads to a landing. What do people think?

The aircraft should always be operated at/above Vyse on the approach until Ach so that a go-around can be flown without needing to accelerate if there's a failure. Following a failure at 500ft (eg) on the approach there are 3 choices:[list=1][*]Asymmetric go-around followed by pre-meditated asymm approach and landing[*]Continue the approach whilst trying to identify/verify/feather[*]Continue the approach without drills[/list=1] My humble opinion is that the safest option is #1. I know from experience that many people coc& up a simulated failure below Ach and reach horrendous attitudes whilst trying to reach the runway from 250ft, I dread to think what they'd do from 500ft.

OKTAS8: Great minds think alike (or fools seldom differ!).
'Agree totally: what DO you do below Vtoss & above Ach or vice versa? I discuss this and usually we end up agreeing that logically you can dive to increase speed, or bleed the excess speed whilst going through the drills.
The bottom line is that below Vtoss the actions are: control, throttles shut, lower nose. Once this is done you can use available power to reach the best landing area - in practise this MAY mean that you find you can reach Vyse and climb. Having just re-read the previous sentence it sounds too positive - has anyone found a better way of expressing it?

(BTW, my only real engine failure was a slow affair at FL100.)
HFD

When comparing operation on one engine during the departure phase to the same during the approach phase one must remember the following very important facts;

1. At departure the weight is higher than during the approach at the end of (or later in) a flight;

2. During an approach, the attitude is low and a simple slight lowering of pitch can regain any lost speed without significant alteration of the profile;

3. During departure, the nose attitude is high, drag is relatively high and potential energy loss when an engine fails is significant

4. Many light multi engine aircraft have negative climb gradients at Max take-off weight

5. During the approach phase, the pilot is minded towards getting the aircraft on the ground and simply closing both throttles and gliding is not totally alien.

6. During the departure phase, the pilot is minded towards gaining height and closing both throttles can be very alien.

When departing, if no positive flight path can be constructed following engine failure then there are ceiling and visibility limitations that provide some posibility of a successful forced landing.

Regards,

DFC

-------
Pilot Bear,

Don't forget that blue line is best rate of climb speed single engine. Just like a single engine aircraft, it can be possible to climb at speeds above and below that speed but the rate is reduced. Of course if the gradient is negative at blue line then just like the best glide speed in a single, either side will vary the rate of descent.

With regard to height and Vtoss h_f_d:

I fly a Seminole, which is a tad lighter than the Seneca, and possibly has a better power-to-weight ratio. However, I deal with the possibility of height loss while doing EFATO drills by specifying Vyse as a decision speed (and gear retraction speed) rather than Vtoss - 88kts versus approximately 68kts.

This has some benefits for low-time pilots unfortunate enough to get a real EFATO.

-They are already at a speed offering best performance.

-The acceleration profile means they are further from the ground before they have to deal with the EF by doing drills.

-If drills are required, the gear is already at least in transit if not up.

-Lastly, the point marking the end of the "close the throttles" region and the beginning of the "deal with it and then assess performance" region is where they retract the undercarriage - an EF after this point does not require thought about airspeed and height, but merely "have I retracted the gear or not?"

I know that to use a height and a speed in the manner you've described h_f_d, is more flexible and possibly more operationally orientated than my method. However, from reading it appears that it takes about five seconds from EF to the pilot reacting logically, and longer if the reaction requires thought / memory. I do worry about pilots I've trained killing themselves while thinking about what has just happened and what they should do.

Hmm. Sorry about the wordiness - hope the sense comes through.

regards to all,
O8

PS never had an engine failure. Book smarts only, hope to stay that way! :ok:

For what it's worth:

We distinguish between the decision height (ADH) and the committal height (ACH). ACH being the absolute minimum considered possible to achieve a safe asymmetric go-around and ADH being some factor added to ACH allowing for pilot ability etc etc. Making the decision at ADH allows some descent while aircraft configuration changes are made. In some cases ACH and ADH may be the same. We use 200' AGL for ACH and min 100' AGL added to this for training; (typically 200' with demonstrated student ability).

What instructors impress upon students is not necessarily what they take with them on their own operations, no matter how clear you think you were. There will always be students who consider themselves as good as or better than their instructor. Does this mean that you failed in your teaching? (This is not to say we shouldn't take any responsibility at all during teaching).

Lastly, in all the talk about IMC asymmetric go-arounds no one has yet mentioned the MAP climb gradient - 2.5%. Last time I checked most light piston twins would be struggling to achieve this at anywhere near MCTOW. This surely would necessitate a higher MDA/DA and an allowance on this height to ensure you were climbing by the new ADH/DA?

AML

Yes, it does. Oz rules specify that the MDA/DA must be adjusted if the a/c would be incapable of achieving 2.5%

Adjust MDA for climb gradient
 

All very good. But to do this, you will need to know where the critical obstacles are, so you can work back from them at the actual climb gradient, and determine your new single-engine MDA.

This information is not in the ordinary approach plates. How many flying schools purchase the missed approach terrain survey maps from the certifying authority, just to do this calculation?

Two further complications:

a) The "ordinary" MDA may not be climb gradient restricted, but restricted for some other reason, such as not below 300' agl at the missed approach point. (This would be the case where a missed approach takes you over water or flat ground, with a turn at a non-specified distance to return to the airfield hold).

b) Your clapped out light twin may be incapable of climbing to, or maintaining, altitude in the missed approach hold when asymmetric. In that case, what's the point of doing the missed approach at all? If asymmetric in IMC, you are effectively committed to land from the initial approach point.

Food for thought, I'd welcome corrections.
O8 :)

Tinstaafl - absolutely correct and Australia is not alone. Any country that constructs their procedures using ICAO PANSOPS will have similar statements in their AIP (or equivalent). What I find interesting, (as far as I can see anyway and happy for someone to direct me here) is there is no guidance provided in any official publication as to how to go about adjusting your MDA/DA. I have a couple of ways and I am sure others have their own.

Oktas8 - I have to confess to being a little confused. I presume the 300’ you talk about in your first point (a) is the normal ADH that one would select, regardless of conducting the flight under IFR or not? And I am unsure exactly what you mean with the comment in parenthesise. Could you explain a little more?

On your second point (b) I agree but with one addition (not really a correction); as you say the MAP is the least desirable option and one should consider themselves committed from the IAP. Therefore (and here is my addition) it would be unwise to even start the approach if visual reference is not assured at some margin above the normal MDA/DA. Put another way; you must establish an actual cloud base prior to approach commencement, this could be from ATC or a preceding aircraft having successfully completed the same approach.

You could take it a step further and say that descent below MSA (be it the holding MSA or route MSA) must not be considered unless a successful approach is assured, the exception being airspace with radar terrain services. I am not suggesting that you will be able to maintain every MSA as clearly any mountainous terrain MSA in a normally aspirated light twin with an engine out will be nigh impossible, but where practical.

Interested in more of this topic if anyone has any.

AML

Yes, sorry askmelater, my post was a little too summarised.

In point (a) I am suggesting that some MDA's are not set at a height to guarantee terrain clearance on a 2.5% climb gradient, but instead are set because it is deemed unsafe to go lower on a non-precision approach.

For example, a certifying authority might decide that it does not want an aircraft descending below 300' AGL until the aircraft is visual to the runway - this is not the pilot's ADH, but is the specified MDA for the approach. For example, let's say that the certifying authority wants 296 feet of terrain clearance at circling MDA, so that is the MDA set.

If the missed approach takes the aircraft over water or flat terrain, then terrain clearance on the missed approach is not an issue, and there is no obstacle clearance related reason for the asymmetric aircraft to use a higher MDA to compensate for reduced climb gradient. The pilot of a light twin that has suffered an engine failure could quite happily go down to MDA, and climb back at a 1% climb gradient if necessary - he or she isn't going to hit anything, so why set a higher MDA than necessary? (I'm ignoring airspace and traffic flow problems in this scenario.)

In my post I am attempting to show that adjusting MDA to account for reduced climb performance is difficult, sometimes expensive, and unable to be done accurately by the pilot in the cockpit - there are too many variables.

Perhaps I should sell my CAA's half-baked effort at an AIP & buy a Jeppesen suite of manuals with some decent PANS-OPS reference material in it!

O8

Much of the discussion in this thread has been on the technicalities of asymmetric GA However; I would be interested to hear views on the philosophy of instruction particularly for students who aim to fly larger JAR 25 aircraft that in general do not have need for a committal height.

One concern is of negative training, where the necessary awareness of committal height in a light twin is then transferred into commercial operations and leads to reluctance to GA from low altitude. First learnt, best remembered.

In addition, how do the instructors on the heavier JAR 25 aircraft, un-teach those different aspects between training aircraft and commercial operation. I exclude the problems of modern avionics etc; at least until a Cessna 172 has a HUD.