Going around > 2.5% climb gradient and 2.1% App/Clb perf 2-eng a/c
 

Taking HK 25L overshoot procedures into account. where normal minima is about 222' with a note that this is based on approx 5% climb gradient and the same approach has a note* stating a much higher minma of some 1,150' minima for 2.5% climb gradient, so based on that and using Jepp procedures, if one overshoots at 222' and turns right as per procedure, then suffers an engine failure staright after going around, will it clear the obstacles due to the fact that certification for 2 engine a/c is 2.1% gross in App/Clb phase yet Jepp procedure is based on 2.5%?

The basic answer is "probably not".
The real answer will depend on the location of the critical obstacle in relation to the location of the aircraft at the time of the engine failure. Pans Ops does not consider an engine failure in the missed approach, or anywhere else in a procedure.

So, the best answer is... if you can't make 5% (or whatever) after an inflight emergency, you must have some contingency procedure in mind. This could be as simple as not going below 1150 feet unless the Tower has confirmed that you WILL get visual - and, of course, you're happy to accept that information!

Or limit your landing weight to the missed approach weight based on 2.5%.

Mutt.

Thanks very much, this has been my argument, I'm not too sure as to what CX or Dragonair or other 2 engine jets going into HK do, however, of the 4 major issues regarding this HK approach:

i.e Engine failure @>
-1 prior to the 2.5% limited minima i.e 1,150
or
-2 after it happens passing 1,150 BUT above 222 the minima (for 5% climb gradient)
or
-3 failure at 222' (5%)
or
-4 commencing the normal missed approach right turn towards the high country 2 engines missed approach (5% no problems) HOWEVER its having the engine failure during this missed approach (worse case being at the MAP).

I'm concerned as to app/clb certification requirements 2.1% gross clearing the required performance of 5% for that missed approach.

Sorry if the above issue sounds stupid, as I'm sure the HK 320 drivers must have faced this same issue.

Jepp provide for a single engine take off chart but that's in the other direction as compared to commencing the missed approach and carrying it out with an engine failing at the critical moment

If a legal eagle looks at this, surely he/she will recommend that the minima for these 07/25 high gross path missed approaches MUST be based on 2.1% to clear those bloddy high mountains therefore the minmas will be around the 1,200' mark where no-one will get in.

Glad to hear from 2 engine ops folk doing these approaches and request what do they do with the above

re-capping - everything is fine, going down to 222' minima based on the 5% gross climb gradient, then overshooting as per Jep procedure, then engine fails on intial part of this approach (your around 300' and you've got to get up to 4,500' on one engine amongst some seriously high ground carrying out the Jep missed approach procedure

hold the phone...

If this climb gradient is specified on the approach chart (I haven't seen it, but assume this to be the case), then the 5% climb gradient is NETT, not gross. Same is true of the standard 2.5% gradient in Pans Ops procedures... I assume the HK charts are based on Pans Ops - not sure what TERPS does, but suspect it would be much the same.

Either way, it makes the 2.1% gross climb figure a tad worrying.

Single engine considerations do not apply for missed approaches unless you are on a single engine prior the missed approach point. It is sort of like the double jeapordy thing. i.e What are the chances of having to do a missed approach and losing and engine. That is not to say that it cant happen, just that you legally don't have to take it into account when commencing an approach on two engines. Should you already be on one engine prior to commencing the approach, then clearly you will need to ensure that you have the required performance to meet the missed approach gradient buy either increasing you minima, or reducing weight.

If you think that this doesn't sound right then consider the fact that having landed at the airfield, you will be taking off at a later point most likely at a far heavier weight, with enough performance to suffer an engine failure at V1, which will be at the opposite end of the runway and some 200 feet lower than at the missed approach point, then continue the take off and survive.

Now you may say "but we have a special procedure for that".

That is my point exactly. If you do suffer the unlikely event of an engine failure during the missed approach, if need be, you should be able to safely follow your engine out procedure, for the after take off case, which will afford you all the protection that it does in the EFATO situation plus the buffer of being higher and lighter when the engine failed.

The solution to the problem lies not in being able to meet the pubished missed approach gradients on one engine, but being aware that you can't, and planning an alternative escape path.

If this wasn't the case, then two engine aircraft would be seriously restricted due to the fact that none of them are certified with a 2.5% approach climb capability.

Rev Doctor Doug,

Hopeful rather than accurate.

I have been summoned by She who Must Be Obeyed so cannot complete my intended answer - let us just say as an opening gambit that anytime you go to a destination with poor weather, the probability of executing a missed approach begins to approach certainty while the probability of an engine failure remains undiminished. It is not double jeopardy at all. You will also find that most legal systems do in fact burden the PIC with descending to a safe minima - and I would love to face your argument acroos the bench in a court.

Be back soon to deal with the other problems in your offering...

Firstly may I say thanks to the above ppruners who are assisting in this serious dilemma.

In fact rwy 07L HKG is:
222' minima with note "based on 7%"
1332' minima for 2.5% climb gradient

the other way 25R HKG is
223' based on 4%
1,321 2.5%

YES I totally agree with the other ppruners, that with engine failures in the 1st 2nd and 3rd areas of my previous posting, one has the ability to make decisions such as following the normal single out take off procedures, as its not that much of a problem as one is flying several hundreds of feet higher than the take off, as well as burning fuel off to get down to lower weight's to check the RTOW's obstacle limit weights prior to commencing the approach etc...

BUT and the BIG dangerous BUT is ONCE you are in the normal missed approach phase, you then lose an engine (or the IRE fails it on you in the sim) THE a/c MUST NOW achive 7% up to 4,500', then there's no way the aircraft is going to miss that mountain once you do the right turn. But hey your at 222+ commencing the turn back towards high ground as per Missed Approach procedures and a lot of height to climb.

Looking very closely at the overshoot procedure, there's a right turn where, one goes on a heading of 100 this takes you within 1 mile or closer of a very high hill (the one JAL nearly touched during an ILS 6 months ago) and with a stiff Notherly, it will most definetly drift you into this high hill.

I'm sure for the huge 777s/330s its no problem on s/e, BUT for 320s/737s surely this overshoot is madness.

As we all know the 2.5% Jep OCA figures aren't based on s/e BUT then, why isn't the s/e overshoot taken into account. This business nowadays takes engine out issues on take off, drift down so why not overshoot, especially for these 2 ILS'.

Is this not a problem? Because, once you are into the "normal 7% missed approach" then you suffer the engine failure, you simply can't come up with your own way of getting out of that normal overshoot by doing a left or right "Uwee" out of the overshoot procedure, as you have obstacles (HK marble)either side of you

I was wondering what do the Dragonair/Air Macau 320s China Airlines 737s pilots do in HK and/or in their sim sessions as I'm sure some psycho TRE's must have played this one out?

Thanks.

hold the phone

I'm a bit confused, you mention runway 25L at HKG and then talk about a RIGHT turn in the go-around procedure. The Jepp charts in front of me show a LEFT turn off 25L ("straight ahead to 7DME, then left to 165 deg") - the right turn is for the go-around off 25R.

Be that as it may, we have an "engine failure - take off and missed approach" procedure in our Jepps and off both 25L & R it involves flying runway heading to 6DME and then turning LEFT ie away from the high ground. This procedure has been approved by HKG ATC - although we are reminded by our trainers to be very vocal about reminding them that we're not following the standard go-around - and takes care of the high ground problem.

Ref your point about what happens if the engine fails during the go-around - it seems to me that the situation will not be quite as critical as all that if you have the engine out procedure that we have. Looking at the all-engines go-around off 25R, you follow the runway heading until 3DME before turning right. Given that this is the ILS DME, which reads 0 at the approach end of the runway, and also that with a DH of 220' you will commence the go-around about 1 mile short of the approach threshold, this means that you will have 6 miles or so between commencing the go-around and hitting the 3DME point and commencing the right turn. In my company, if the engine fails at any time in these 6 miles then we will not turn right at 3DME but continue to 6DME and turn left. No problem. In the worst case, if an engine fails at 3DME just after we've begun our turn to the right, then will this really be a problem? We've had 6 miles of climb on all engines - we will probably be close to 3000' already. Still a very tense situation that will call for some quick decisions, but not quite the emergency situation that you envisage.

I hope this helps.
t

(Edited for kak spelling, grammar and syntax!)

This is one of two ops eng problems which have been with us for a long time ..

(a) what to do if the failure occurs on takeoff sometime after V1 ?

I am informed from reliable sources that some operators (and I include at least one large operator) schedule the failure procedure for a V1 failure and ignore the post-V1 failure scenario ... problem belongs to the pilot ...

Not a problem if you are intending to follow the OEI procedure .. but might present one if the SID takes you in a different direction over tiger country.

Hopefully the majority of operators address failures at any position up to a sensible obstacle clearance level and provide escape sequences to suit.

There have been a few threads on this topic alone ..

(b) what to do with a failure during the approach/missed approach ?

Same deal. I suspect that many bury their heads in the sand and ignore the problem.

Others address it specifically and schedule escape procedures and/or higher minima to avoid the problem.


Certainly, for each,

(a) the most inappropriate time to think about what you ought to do is after the failure occurs .... bit late then

(b) the pilot generally doesn't have enough data to make a rational engineering assessment of the problem (obviously there is not much of a problem if there is no terrain to consider)

(c) ought not a corporately responsible operator consider these matters ahead of time and provide appropriate and necessary guidance for the benefit of crews ?

Just a couple of observations:

1. Jeppesen do not "design" instrument procedures. They re-publish procedures already in the public domain using their own format. The HKG procedures were designed to PAN OPS criteria by the HK CAD.
2. PANS OPS will give you a 30m (100ft) obstacle clearance in the initial phase of the MA until a 50m (165ft) clearance is achieved. TERPS is slightly different - the obstacle clearance is 250ft, but the obstacle assessment area is smaller, significantly so for Cat C & D aircraft.
3. OEI performance assessment and contingency planning is the responsibility of the operator. However, normally the obstacle assessment area is much smaller.

hold the phone...

How do you suggest that we do that? What baseline aircraft type should we use, in determining an appropriate OEI missed approach climb gradient? It's an impossibility because we, as designers, don't know :-

1. WHERE, in the procedure, the failure will occur; and
2. WHAT nett climb gradient will be appropriate.

The protection area would be so broad that the DA/MDA would be completely useless. The 2.5% basis is just that, a basis. What you are being told on that HK approach chart is that, if YOUR aircraft cannot climb at the higher gradient, for any reason at all, you must either use the higher DA/MDA based on the lower climb gradient, or have already done your own performance appraisal and set a DA/MDA that will be safe for YOUR operation.

Some airlines employ people to do that, others contract the work out to somebody else. Some MIGHT just bury their heads in the sand. I hope, for your sake, that your company isn't in the latter group.

It IS legitimate for a procedure designer to apply a non-standard missed approach gradient, where necessary, to achieve the lowest possible DA/MDA. Pans Ops says we can go up to 5% without industry consultation. The steeper climb gradients recognise that advances in aircraft performance mean that some aircraft types can take good advantage of it, while others cannot.

That is a fact of life.

It also needs to be said that Pans Ops (and probably TERPS as well) regards the missed approach as an emergency situation. That is to say, a situation that should not arise frequently and, therefore, the actual risk associated with the use of it should be minimal. This is why you are given so much less obstacle clearance in the missed approach, compared with the various segments of the approach itself.

I'm not going to enter an argument about the rightness or otherwise of the philosophy of an "emergency situation", I am merely stating the fact. I suspect that what you are really after is the fruits of the performance assessment work that has undoubtedly been done for or by Dragonair, Air Macau, etc. They will have paid a LOT of money for that assessment, so they won't be willing to give it to anyone - that's just a commercial reality.

Tired, Thanks very much for giving me some answers and insight into the 25R overshoot. I apologise for the confusion on which runway I was talking about, yes you’re correct 25R was what I was trying to resolve. Again thanks Tired.

I’m sorry OzExpat if you feel I have an ulterior motive by trying to squeeze out of any pilot, some very expensive research information that their company has done in this area then please believe me, that is certainly not the case. If any other airline were ti use data from another airline without their permission were found out, then there would be serious court action for compensation. No not at all.

What I’m trying to do is both self preservation AND until my airline can be convinced that they must look into this and use one of the many international firms that specialise in airfield performance analysis and to produce their own approved missed approach.

Tired, forgive me if this sounds stupid, however, until I go back to work to look at the 25R chart, if the MAP is say approx 1 mil prior to 25R threshold and the right turn on 2 engines is commenced at 3 miles then isn’t total track miles 4 miles.

I couldn’t agree more with you that @ the 3 miles point on 2 engines AND you’ve commenced the right turn towards that very high ground, you should be “fairly” comfortable with obstacle clearance. At max landing weight or the 2nd segment/obstacle limit weight and doing this missed approach once you are committed to the right turn with some “fairly” decent height, the aircraft must perform all the way up to 5,000 OCA as published, do you feel that still a fair way to go.

And the other major concern I have to the designers of this published approach is the above situation engine fails as the right turn happens @ 3DME (you have some good height so far as you’ve been on 2 engines at your referred max limit weight and when you do the last step of this missed approach that is, you turn right on a heading of 100, you sail very very very close to the “JAL DC10” hill with the radar on top of it, with a stiff Northerly and you’re “making good” your 2.1% gross climb as per the certification of the 737/320s, not 7% ala chart, do you think you will come home for tea?

I’m glad the others agree that this issue whether its HKG or anywhere else in the world, does seem like its head in the sand stuff!

To John-tulla, Reynolds and OZ, once again many thanks for some good stuff discussion, answers on this important issue.

In our operation if we were flying the 25R approach SE then we would demand the company EOSID which would take us staright out to 7 miles on the ILS DME and then turn left. We would not consider doing the standard missed approach. If we were in the G/A before the 3 DME fix then the same would apply. However if we were pointing to the high ground then lost a donk and were concerned about terrain clearance (overweight landing due immediate return for example) then it would be immediate radar vectors away from the high ground! In practice I think you'll find that HKG ATC would assist with a clearance in such a way since there have been some windshear go-arounds off this approach where people have not wanted to turn back into the shear area.

hold the phone - yes, you're right, it's 4 track miles not 6. Maths never was my strong point. :( But 4 miles will still give you a fair amount of height to play with at 3DME.

I think idg has summarised what I was trying to say much more clearly than I did. Your operator should provide you with an Engine Out escape route (for EFATO and go-around situations) at any destination that is dicey and if you are making an engine-out approach then you should plan to fly the EO G/A rather than the normal one. If your operator doesn't provide such things, then it would behoove you to think about it yourself and come up with your plan "just in case". In either event, make sure ATC knows that you'll be flying a non-standard G/A.

As for what to do if the engine fails just as you're turning at 3 miles- again, I think idg has hit the nail on the head - yell for radar vectors (and keep the climb going). ATC at HKG is pretty good at that sort of thing.

Happy New Year to all.
t

In the Airbus FCOM there are provided Charts for several climb gradients(in the other world called WAT limits)and the max'weights for 'Go-around"(Fcom 3.05.35)..Although one uses 2.1%gradient,for the G/around,one is required to miss with a 2.4&gradient after a CAT2...Generally reviewed on Line Indoc'-but missed by most.
cheers;)

Reverend Doctor Doug,

The other comment that I was intending to make is in relation to using the take-off procedure in lieu of the published missed approach procedure.

The key issue is in positioning the aircraft during the missed approach to ensure that it is contained within the very, very narrow corridor used to maximise take-off weight. If your missed approach point is about 2 miles from the far end of the clearway and you are in cloud with strong crosswind and suffer a yaw-exacerbating engine failure during the go-round, what are your chances of establishing the aircraft within 1-200m of the centreline at the end of the clearway? From my observations, quite remote!!!

Given that the very, very narrow corridor used to maximise take-off weight may indeed pass between a pair of very steep obstacles, positioning to avoid those obstacles is obviously fairly critical.

OzExPat,

I don't know that ICAO consider missed approaches to be "emergency situations" so much as "unusual". I suspect that there are (and should be) far more more missed approaches conducted for a range of operational reasons than there are engine failures - we would look a bit silly encouraging pilots to make a missed approach rather than an unstable landing if we were then encouraging them to get involved in an emergency situation with a low probability of success.

Nonetheless, you do raise the key issue of missed approach analysis - where to start and what sort of splay to analyse.

There are many questions and many imponderables:

Does the PANS-OPS missed approach design offer sensible lateral containment?

How far down range is the aircraft before it is re-established in a missed approach configuration for which climb data is available or can be determined?

What options exist for safe flight paths below the landing minima and for missed approaches from circling?

Will reduced lateral tolerances for VMC operation provide better options?

What is an acceptable level of risk for operations in difficult terrain, recognising that complete and guaranteed safety for all contingencies will not permit flight operations at all?

I could go on, but suffice it to say that ICAO has not addressed the issue directly as is the case for most regulators. Additional certification data for all engine climbs and OEI missed approaches that go far beyond the present requirements would have to be mandated as a first step - very expensive and likely to be strongly resisted by manufacturers and operators alike. Foe operators, the costs involved in providing "what ifs" are huge and do not stand up to cost benefit analysis in our low margin but extremely price sensitive aviation game. One can provide reasonable rather than perfect advice - in the end, the commander is the risk manager on the spot.

But don't misunderstand my personal view - more advice is always better and should be demanded by flight crews - but the expectations must be tempered with realism.

4dogs... yikes! You've asked some pretty awkward questions that Pans Ops isn't exactly geared up to answer. Indeed, as I'm 500 NM away from my books right now - and for the next week as well - I'll have to go from memory on the finer points. However I'll preface this by saying that the sort of questions you've asked are the very reason why airlines need to do their own sums for their particular aircraft, philosophy and SOPs.

The point here is that you can only expect 100 feet of obstacle clearance, in the intermediate segment of a straight missed approach and 164 feet in a turning missed approach. That's a bit of a simplification, but it is still the basic fact. The ICAO Obstacle Clearance Panel came up with those values based on experience and a statistical probability of the number of times a particular missed approach would need to be flown, versus the number of times it would not need to be flown.

It is, therefore, a risk management exercise, based on the expectation that the missed approach would be used infrequently and, therefore, a lower level of risk is achieved. This allowed the OCP to determine that a very small amount of obstacle clearance is necessary in a missed approach. Yes, I'm doing a bit of second-guessing here, but no other explanation seems to make sense when considering this quite small amount of obstacle clearance.

This might depend on the philosophy in the particular country. Pans Ops says that a straight-ahead missed approach splay can be the same as the final approach splay. I know of a number of countries that apply that statement verbatim. This requires track guidance from the azimuth aid used for the approach, so it begs the question about how much lateral protection do you have if the navaid failed?

In my dark corner of the world, that is a very real consideration, so I do not routinely apply it. Thus, I am forced to use the alternative Pans Ops missed approach splay, for DR Nav., which has a splay that expands at 15 degrees, rather than the 10.3 degrees for NDB guidance or 7.8 degrees for a VOR. Clearly, the extra degrees that I must allow for will bring more terrain into the missed approach area and this can, often, control the MDA for the whole procedure.

As to the matter of what is "sensible". I suspect the answer here is that beauty is in the eye of the be(er)holder!

This depends on the maximum speed allowed in the missed approach and that speed will be different for every category of aircraft that is authorised to use the particular procedure. I can't give a direct answer here but the following is a guide that uses a fairly typical situation in my part of the world...

All values for 2000 FT AMSL, ISA+15 and, before the purists jump down my throat, these values are approximate because I don't have my books or calculation routines with me. However, these values will be about right and will give an idea of the sort of allowance that must be made.

Cat A (110 KIAS) 0.8 NM
Cat B (150 KIAS) 1.1 NM
Cat C (240 KIAS) 1.6 NM
Cat D (265 KIAS) 1.8 NM

The above distance is required for transition to climbing flight, after pilot recognition of the missed approach point. There might need to be an additional 0.1 to 0.3 NM to add on, to allow for pilot reaction time after recognising the MAPt.

This is a HUGE question that falls in the category of the "preface" comment, above. The simple answer, as far as Pans Ops is concerned, is ... none. Indeed, for circling, all bets are off because the missed approach is designed to start at the missed approach point, not at some unknown point within the circling area. Thus, the pilot is on his/her own if there is a need to initiate the missed approach from anywhere beyond the MAPt.

Undubtedly! Your only problem here is trying to convince the ICAO OCP of it. Of course, if the weather is VMC, the likelihood of hitting a hill you can't see is usually much reduced.

Strewth!!! How long is a piece of string? This is the VERY reason why airlines MUST crunch their own numbers - or get someone to do it for them.

Most of the above is pretty academic anyway. The reality is not so much the State compliance with Pans Ops - insurance premiums are based, in part, on the assumption that all instrument procedures comply with either TERPS or Pans Ops criteria. If any State regulator moves away from that criteria, there could be significant insurance premium penalties on airlines that operate to, from and within that State.

And, in the event of a prang, there's a pretty good chance that the procedure designer and the State will share liability. I don't know of any State regulator that will let that happen so, unless ICAO modifies the criteria in any of the ways you're suggesting, I don't see any contracting State regulator sticking its' head on a chopping block.

I hope this clarifies the situation for you.

Happy New Year!

4dogs
 

I hear what you are saying. I recently talked to our performance guy and he basically agrees with what i have said. But having said that, it is only applicable to my airline because that is our policy. i.e We do not have to consider single engine missed approach gradients if we are planning a 2 engine approach. According to our performance guy, Boeing was asked the same questions and their reply was something along the lines of "it may not be safe, but it is legal".
I also share your reservations about the safety of this theory, however, in lieu of any published escape routes, all we can do is fly the engine out procedure. It is our safest bet. It becomes an even darker shade of grey when you consider the engine failing at a point beyond the initial turn in the engine out procedure. As some one else mentioned, one can only hope that the altitued achieved on 2 engines to that point will have put you in a reasonable good position. So in fact my response was not at all hopefull and was in fact accurate, according to our SOP's

Cheers

Oz & Rev,

The reason I threw in the extra bits was as a consequence of trying to design some guidelines for Missed Approach Analysis.

One of the major impediments is in terms of certification data for missed approaches - the mandatory requirements are few and the data required can be extremely expensive to acquire, if indeed it exists at all. The ability to somehow finesse the Take-off data is generally hindered by the lack of high quality AEO flight path information - climb data is not required for AFMs other than broad altitude/distance/fuel burn type data which is useless when considering 100 foot clearances from obstacles.

Boeing are right: the question gets down to legality and, more importantly, liability. I suspect that an OEM will only get involved in Missed Approach Analysis to the extent to which they are legally compelled. As I try to imply previously, it is a question easily asked but almost impossible to properly answer.

Oz, wander down the road and ask the boys to explain the AEO and OEI missed approach analysis for Goroka for the F28 - I am quite positive it will be interesting.