Missed approach procedure is baesd on what performance?

[wondering]

At one of airfields our company flies to, published minimum MACG is 5%. No mountains there, I don't know why exactly is it so high.
Let's assume that approach climb gradient, calculated by performance app in the EFB, or extracted from AFM tables is exactly 5%.

ATC or airspace requirements? Some SID charts which have higher than standard climb requirements often have a statement to that effect e.g. Nice. I reckon the same is true for some approaches.

[cosmo kramer]

@Skyjob, nice quotes. But CS-25 deal with certification specifications for lange airplanes.

If your aircraft doesn't meet the requirements in CS-25, it wouldn't fly at all, as it would not have been certified.

Try again....

[cosmo kramer]

Thanks guys.

I know that the standard missed approach gradient is 2.5%.
So, does it means:
1.In case of one engine inop, as long as I can still have a climb gradient > 2.5% during missed approach, I can just follow the published missed approach procedure?
2.In case of one engine inop, and I can not have a climb gradient > 2.5% during missed approach, I need to follow the special engine out procedure instead of the missed approach procedure?
3.In case of one engine inop, and I can not have a climb gradient > 2.5% during missed approach, and there is no special engine out procedure, then I either maintain runway heading and climb to MSA and request radar vector, or I follow a SID which is appropriate?

BlackandWhite2000, in principle, you only ever fly the standard missed approach with all engines operating. Because this is what the procedures are designed for. First freaking paragraph in ICAO Doc 8168!!!

I don't know why people have so much trouble getting their heads around this. It is generally accepted not to fly a SID with an engine out. But most people seem to believe you have to be able to fly a G/A single engine. Some even believe you have to leave passengers or luggage behind, if not able.

Fact is, that you only have to meet the gradient with all engines operating.

So what do you do if an engine fails:
You ask your operator! Just like ICAO wrote:

Note.- Development of contingency procedures is the responsibility of the operator.

If your operator doesn't have an answer for you, the you report them to the authorities, refuse to fly and start looking for work at a serious company.

My operator specified engine out G/A procedures for every runway we fly to. Mostly they are identical to the takeoff engine out contingency procedure. Or they may be identical with the published G/A. In both cases the company from where we get our performance data, has calculated that it is possible to fly the procedure with one engine out.

In no case do you start to make calculations yourself (unless you want to make yourself a criminal). 2.5% may be a no-brainer. But what if the published missed approach has a gradient of e.g. 6% to 7000 feet, and the procedure contains several turns?
You have no chance of make a reasonable calculation yourself. Even from charts in the performance manual. Remember you gradient diminishes in a banked turn. So even if you are able to calculate an average, you still don't know if the mountain peek is just at the place, where your gradient is lower than the required average, because you are in a bank.

[cosmo kramer]

Microburst2002
We must not confuse approach climb gradient requirements with obstacle clearance for the missed approach procedure!

Exactly.

Allow me to elaborate:

Regarding approach and landing climb for certification, these are just ways for the authorities to ensure, that the aircraft being certified, is able to climb somewhat at all. They (FAA originally) deviced these manoeuvres and set the requirements, that needs to be demonstrated, to a level that they decided was to be considered safe.

It has nothing to do with obstacle clearance. They demonstrate that the aircraft has a certain climb performance, nothing more, nothing less!


A complete different authority (ICAO), set a limit for minimum obstacle clearance during (all engines operating/normal/standard/day-to-day) go arounds. Their assessment of what is safe resulted in a minimum required gradient of 2.5%. For our modern high-performance aircrafts with gradients in the 15%+ range, this is not a problem (remember these requirements were set in the 60'ies and applies to propeller/general aviation aircrafts as well).

[arxipov]

Thanks, cosmo kramer. Makes sense now)

[john_tullamarine]

Folks,

The confusion is common and has been so for aeons. If I may be permitted to add to cosmo kramer's observations, above ..

The Certification Standards (eg FAR25) are concerned with providing a vehicle which is reasonable to fly and repeatably so. Indeed, one could say that one FAR25 Type is much the same as another for aircraft in recent decades and that is the intent of the Standards and certification processes.

This is addressed without any particular concern about runways and rocky bits.

What you do with the vehicle once you get your hands on it is a whole different ball game.

Then, for obstacle considerations, it becomes an ops engineering concern.

At the end of the day the Certification Standards (eg approach and landing climb WAT limits) conspire to constrain the MTOW and MLW without any consideration being given to the runway and airport environs.

If the runway or obstacle situation dictates, then the AFM limiting weight must be reduced further to accommodate whatever ends up being the critical case for the particular operation.

[Microburst2002]

Accel alt after eng failed in a missed approach

Regarding the issue of when to accelerate after an actual engine failure in a go around, the notion that I have is that if your company does not have a special EOMAP designed for that runway (because it never does such thing for any runway) then you should fly the published missed approach procedure and accelerate at the missed approach altitude, and not earlier (because the procedure is not designed for level segments, and even if the overall average gradient is better than the gradient required, it might not cover a level off part of it)

In companies which do provide EOMAPs, but in a runway that does not require one, it is supposed that you can accelerate like in the failure case after take-off, with an intermediate level off acceleration segment. The EOMAP is only required if you cannot make it like that. Or maybe it depends on the provider and in other cases, in those runways that don't require an EOMAP you have to accelerate only at MAP altitude, just in case.

[7478ti]

[Real] RNP fixes all this MAP/GA safety

The above thread is why both FAA's AC120-29A issued on Aug 12, 2002, as well as ALL [real] RNP based procedures, ...now specify providing protection for air carriers for safe obstacle clearance for the balked landing from the TDZ, while still accommodating the first engine failure, as well as the first NAV failure. That way, loss of visual reference is protected all the way to the runway, as well as for any go-around, irrespective of above or below DA(H), whether initiated OEI, or having an engine subsequently fail at any time after a balked landing (even near the TDZ) has been initiated. Both TERPS and PANS-Ops, as well as other some other states' operations and SIAPS used by air carriers do not necessarily address this issue, ....for assuring a safe go-around missed approach path, for any G/A initiated either before or after descending below DA(H), ... such as in the event of an unsafe (blocked) runway, low mu report or observation, excessive wind component, windshear, or loss of visual reference. This safe go-around protection has always been intended for US air carriers since the jet age, but was only explicit for Cat II and Cat III ops, until it was formalized on July 13, 1999 in AC120-28D, and in 2002 with the publication of AC120-29A (para 4.3.1.8).