B737NG-SE climb gradient

[sean1982]

Hi Everyone,

I've been looking everywhere but can't find it. This was asked by a TRI. What is the single engine climb gradient of the B738 after an engine failure after V1?

Thanks!!
Sean

[FCS Explorer]

maybe just take the
Go-Around Climb Gradient - 1 ENG APP / 1 ENG GA -table
ain't exactly the "on take-off"-thing, but flaps is 1 and engine is also 1 :}
...and then it depends on engine-rating, GW, OAT, bleed config etc etc...

[gas-chamber]

How long is a piece of string? Could be 10% if no pax and minimum fuel. Could be 1% if overloaded. He should have asked what is the MINIMUM gradient. Answer: the same as all other twin engine aircraft above 5700 kg. Freely available from a read of the regulations, so I won't tell you for your own good.

[sean1982]

Well, the situation is the following. An SID on a runway where you need a minimum climb gradient of 5.5% for obstacle clearance. The airport is largely surrounded by mountaineous terrain. The TRI's question was: If you have an engine failure, not at V1, but during the initial climb (eg 700ft AGL) would the B738 still meet that required climb gradient to clear all terrain and obstacles.

I can't use the go around tables as this for F15, which gives me a climb gradient of 6.4% for the given conditions. But this is for a typical Landing weight with flaps 15 and VREF40+15

Thanks

[vino]

yer B738 is certified to accomplish 2.4%, reduced to 1.6%,;) after airframe/pilot technique-this is 2nd segment (most limiting) out to 1500'AGL (No ET)
Your TRI was inviting comment on terrain clearance/airspace gradients.So you then need to address the most important(to you) and make a judgement whether you can meet them.
Your call???
Vino
edit-sorry-wrong figure in there

[KristianNorway]

Hey Sean

Sorry.. I have to be rusty. Why the 5.5% for obstacle clearance?
Isn't the normal PANS-OPS requirement 2.5% OIS + 0.8% margin, giving a standard 3.3% gradient?

I cannot find the performance tables for SE F5 climbout myself.

As long as you're following published engine failure procedure you have an acceptable margin at MTOW, but I understand that's not the question.

I'm looking forward to see an answer.

[KristianNorway]

Ahh.. 5.5% as a local requirement. I guess you're right.

But yes. A emergency procedure with straight T/O - path or emergency turn does according to EU-OPS guarantee clearance at MTOW.

What you're mentioning is the normal departure route, and that's of course subject to performance increments depending on weight.

[skywalk]

Question here is: At deviation point(point where EFP and SID deviate) if you started the turn to follow the SID and then engine fails what you should do. Continue on the SID? If you continue on SID what is your guarantee that you will clear the obstacles on the SID with 5;5 % climb gradient required?

[Ocampo]

Well, I'd say: It depends upon where you are or where that point is located and current aircraft performance. If you are past the second segment, light weight, have visual, well, the decision is not that difficult, I think.

However, if you are heavy, climbing through the second segment, it's a hot day...certainly it would require some mili-seconds of thinking, but still, I'd rather take the safe side, that is, if the engine failed at the "deviation point". Your point of advantage would be if you know this airport and you know you can somehow "switch" from the SID to the company's engine-out procedure.

Besides, from what I've seen of this company engine-out procedures it tends to somehow follow the SID until a point where it's not that critical, altitude-wise.

All that taken into consideration, with a 5.5% PDG and an engine-out, I'd do my best to get into the track the company engine-out chart depicts.

[repulo]

Climb gradient:

If you are asked in the sim or in reality if it happens to you, just look at your FPV.
Take the value you see, multiply it by two and subtract roughly 10%. Et voila.

For examle FPV 2.5° X 2 = 5- 10%= 4.5%

This way you can memorize some values for the all engine case and get a better feeling for the performance of your aircraftor, or be able to judge the performance when having an actual engine failure.

Regards

repulo

[BOAC]

It's an old 'chestnut', the engine fail around the SID. It is something you need to have at the back of your mind for every departure where there is a significant obstacle/terrain, to know when you are 'past it' (so the gradient may not still be required) and to know a 'safe' route if the donk goes !IMC! and it is basically normally just commonsense (may I say 'airmanship'?). You have to rely on a combination of local knowledge and hopefully a decent chart and with any luck a crafty look out of the window. One example of a problem area would be where the SID says, say, ahead to 1.5 miles and turn right xxx (which avoids terrain ahead but actually takes you towards a ridge of hills a bit further away - but not a 2-engine problem) and the emergency turn says 90 secs from start of roll turn left to heading xxx - and your donk quits half-way round the right turn. Your call, Captain?:) Best to have something in mind!

Very few E T procedures are WRITTEN for failure at more than one point, CMF is one case I can think of.

[Tee Emm]

follow an emergency turn manouevre ( the construction of which is the operators responsibility

Be very careful, here. You need to ask the performance engineer company that provides your take-off runway analyses charts to how far from lift off is their surveyed obstacle clearance charts valid. Some operators cut off their charts validity a lot closer than you might hope. That leaves the pilot in a no-man's land of possible critical terrain and wearing responsibility for his own obstacle clearance.

[BOAC]

EUOPS requires a safe engine-out route to either en-route MSA or return MSA as applicable. I know at least one operator who ignores that!

[PantLoad]

Please tell your TRI that the aircraft will make the 5.5% required climb gradient; otherwise, you were not legal to takeoff at that weight to begin with. This assumes that (1). There is no S.E. procedure, or (2), if there is a S.E. procedure, you've past the indifference point upon which the S.E. procedure and All-Engine-Operating SID are predicated.

If the aircraft cannot make the SID's required climb gradient, you must:
(1) Select another departure path, or (2) Reduce takeoff weight to make the SID gradient should an engine fail, or (3) Have a S.E. procedure.

Worrying about 'what if' after takeoff is stupid.....and illegal.

Fly safe,

PantLoad

[BOAC]

Not so, PL. I have personal experience of airlines where the engine out procedure is surveyed up to 1500' clean above the airfield - and then......................?

"Worrying about 'what if' after takeoff is sensible"

[PantLoad]

Yes, you're right...worrying is sensible. I should have written my sentence more clearly. The worrying should be before the takeoff....not after, when it's too late. When you're out of airspeed, altitude, and ideas is not the time to wonder 'what if'.

I flew for a major carrier in the U.S. In the U.S., it's against the law to takeoff when, after a takeoff an engine fails, the resultant climb gradient is insufficient to safely continue the climbout.

In fact, our routing across the Rockies depended on our weight, temperature aloft, and the resultant drift-down performance. In cases of relatively heavy weight, ISA plus XX, etc., our dispatched routing was specifically filed for those conditions....and the unlikely event of an engine failure enroute. If ATC were to offer to us 'Cleared Direct to XXX', we were not necessarily legal to accept it....even though it saved time and fuel.

Can't speak about your airline or your country. Frankly, I'm ignorant.
But, I can say with confidence, in the U.S., in the event of an engine failure, you have to be able to clear the terrain or you change either your routing, your weight, or both. This applies to all phases of flight.

Fly safe,


PantLoad

[john_tullamarine]

if you started the turn to follow the SID and then engine fails what you should do

In the ideal world, your company will have done the sums and your OM published procedures will address any reasonably likely eventuality .. ie follow the procedure should be the mantra.

The reality is that some operators don't do what they should and the crew (and pax) are left between a rock and a hard place in the event of an awkward failure.

Either you do have the sums done and a suitable procedure or you are trying to wing it.

Which alternative would you prefer to argue at the enquiry after the accident ?

[Ocampo]

Well, we got ourselves into a nice little discussion here. I perfectly got BOAC's point, so I suggest ourselves to discuss the "most critical" part in an engine-out takeoff.

I would say the 2nd segment (2.4% CLB requirement) would be the most restrictive part of the whole engine-out procedure or SID. Should an engine failure occur after the second segment, I think it would be feasible for an airplane to continue the (regular) SID for a return to the departure airport, and I'd say it would be an option to consider, IF safe means to fly the company procedure are no longer, well...safe :O

I am well aware of the infinite combinations of factors that could make this statement easier or harder to be accomplished in real life; but I stand to be corrected.

Best regards

[john_tullamarine]

I would say the 2nd segment (2.4% CLB requirement) would be the most restrictive part of the whole engine-out procedure or SID.

Maybe .. maybe not.

So far as obstructions are concerned, any segment can be limiting for a particular takeoff (depending on just where the rocky bits are) and the tricks we adopt will follow from which segment is causing the problem.

So far as WAT limits are concerned, the limiting segment may well be reasonably consistent.

Two different considerations, however ...

[BOAC]

In the ideal world, your company will have done the sums and your OM published procedures will address any reasonably likely eventuality .. ie follow the procedure should be the mantra. - exactly, John - 'ideal world' - I don't want to make a big meal of this, but my point is that one should be 'thinking' of all eventualities. As a DanAir Fleet Manager once said "that is why we put 4 stripes on our Captains' shoulders":). There are not many airports where the problem presents itself, so it is not an impossible task. I do not think that it is reasonable for published procedures to cope with failure at many points, and often "if past ET point, follow SID" (NB we have checked!!) would be fantastic, but not in the real world.

As ocampo says, often where there are potential 'traps' further along the SID, it is often possible to turn back towards the field to pick up the ET track - but not always.

[Ocampo]

So far as obstructions are concerned, any segment can be limiting for a particular takeoff

Oh right! :ugh:

Well, that's when experience comes in handy :}

If you know the airport, you might as well know which "rocky bit" is restricting your departure.

[john_tullamarine]

Well, that's when experience comes in handy

The only experience necessary and appropriate is knowing how to use the AFM and where to get the objective obstacle data. Any suggestion that generic flying experience has much relevance for missing rocky bits during an OEI climb out is misguided at best and dangerous in general.

If you know the airport, you might as well know which "rocky bit" is restricting your departure.

He who doesn't know either explicitly or implicity (if you are putting your trust in the ops engineering section) .. shouldn't be flying heavy aircraft.

Point is which segment is relevant depends on where the critical obstacle is located for the particular takeoff ... can be segments 1, 2, 3, 4 and, if you have an old machine, maybe even 5. The oft-heard suggestion that second segment is always critical may be based on observation but is flawed logic.

[cosmo kramer]

sean1982
I've been looking everywhere but can't find it. This was asked by a TRI. What is the single engine climb gradient of the B738 after an engine failure after V1?
Depends on a lot of factors like weight, pressure altitude, temperature, and configuration (bleeds, anti-ice). There is to my knowledge no where to look that up but no necessity to know either, since...

Sean1982
The TRI's question was: If you have an engine failure, not at V1, but during the initial climb (eg 700ft AGL) would the B738 still meet that required climb gradient to clear all terrain and obstacles.
...those that make your takeoff aerodrome analyses charts have already figured that out for you. If you have a special procedure then you do not meet the required gradient. If you don't have a special procedure then you meet the gradient.

Skywalk
Question here is: At deviation point(point where EFP and SID deviate) if you started the turn to follow the SID and then engine fails what you should do. Continue on the SID? If you continue on SID what is your guarantee that you will clear the obstacles on the SID with 5;5 % climb gradient required?
I would say that this is (should be!) accounted for in the special procedure. If you passed the deviation point you continue on the SID till the SID ends, or to the next deviation point. There is an example of multiple deviation points in the bible document Doc 8168 (http://www.scribd.com/doc/17095960/Doc-8168). Page 1.3.1.4, Figure I.1.3.3. The example is GVA, Switzerland RWY 05. 1) Continue straigth ahead to the VOR and hold, or 2) If you started the left turn on the SID, continue the turn 360 degs and fly to the VOR and hold.

To some of the other posters. Making your own special "special procedures" based on where you might think you remember the rocks are, while IMC could be dangerous imho.

[BOAC]

Making your own special "special procedures" based on where you might think you remember the rocks are, while IMC could be dangerous imho. - agreed, but better perhaps than impacting an obstacle? You are now making the assumption that all airlines include the whole GVA brief in theirs! What if a particular airline's GVA 05 performance page has no emergency turn because there are no obstacles in the way up to 1500' and clean? What then? Best to have thought about it?

[Ocampo]

To some of the other posters. Making your own special "special procedures" based on where you might think you remember the rocks are, while IMC could be dangerous imho.

No argument there.

So, J_T, may I kindly ask what would you do if you experience an engine failure beyond the deviation point, on an airport with "rocky bits" that you are familiar with, and is your believe that you have passed by the "limiting" part?

Would you continue on the SID? Would you try to return to the company procedure track if safe means to do so exist?

Regards

[john_tullamarine]

So, J_T, may I kindly ask what would you do if you experience an engine failure beyond the deviation point, on an airport with "rocky bits" that you are familiar with, and is your believe that you have passed by the "limiting" part?

This is the crux of the usual arguments which the likes of OS, mutt, me, etc. like to see on this forum. Points of interest are -

(a) presuming that the operations engineering analysis has been performed competently (ie the published procedure is technically correct AND addresses the situation of a failure at ANY point in the SID) I will just follow the procedure as published. In the circumstance you describe, such a well-conditioned procedure will be prescriptive and instruct me as to the tracking decision I should make. Unless I, personally, were involved in the analyses, I may well not "know" precisely which bits are limiting - I don't need to know that information to conduct the operation .. providing that the analysis has addressed the requirements.

(b) if (a) doesn't apply and, regretably, that is the case far too often, then

(i) either the pilot (preflight) has endeavoured to do something in the way of a rigorous ops engineering analysis and will follow whatever strategy his analyses produced, or

(ii) the pilot (inflight) flies on a wing and a prayer. The pilot takes a stab in the dark on the basis of little, or nil, objective information and analysis ... and either gets away with it (this time) or CFITs.

Would you continue on the SID? Would you try to return to the company procedure track if safe means to do so exist?

I guess you are advocating option (b)(ii) above ? Perhaps you even subscribe to such as a desirable philosophy .. ?

if safe means to do so exist?

What does this mean ? .. and how does the pilot measure it ?

My response overall to your question ? There is not enough information given to make a defensible rational comment.

However, I will opine that I'd be flying for a different and more responsible operator ....

[BOAC]

However, I will opine that I'd be flying for a different and more responsible operator - so, that takes care of JT's backside. What about the travelling public and crew and the poor hill walkers on the lump, since we all recognise that (a) (i) is ideal but not universal, (b) (i) is extremely unlikely and (b) (ii) is extremely common? Who's problem is it then? Is that not the issue? Are the regulators being thorough enough in this age of SMS and self-regulation?

[Quality Time]

You answered your own question IMO.

so, that takes care of JT's backside. What about the travelling public and crew and the poor hill walkers on the lump, since we all recognise that (a) (i) is ideal but not universal, (b) (i) is extremely unlikely and (b) (ii) is extremely common? Who's problem is it then? Is that not the issue? Are the regulators being thorough enough in this age of SMS and self-regulation?

All flying and planning is based, whether you like it or not, on statistical values. There is an 'acceptable' fatal accident rate in all forms of transportation - (bad luck if you happen to fall into it)

[BOAC]

The question was for JT!

[Ocampo]

Well, first of all, thanks for the reply J_T

Now, by this

Would you try to return to the company procedure track if safe means to do so exist?

Yes, I meant this

I guess you are advocating option (b)(ii) above ? Perhaps you even subscribe to such as a desirable philosophy .. ?

I'll agree with your opinion, it is not a "desirable philosophy", but then again...

However, I will opine that I'd be flying for a different and more responsible operator ....

...there are "such" carriers that does not have the required procedures, analysis and whatever. What's left to do in that case?

What does this mean ? .. and how does the pilot measure it ?

I had in mind something like being in VMC, no significant obstacle towards the EO procedure (Did I make my point across? :confused:)

since we all recognise that (a) (i) is ideal but not universal

Absolutely.

Best regards

[Quality Time]

The question was for JT!


Then send him a PM!

[BOAC]

Oh dear - what we have to deal with! I obviously should have made it clearer for you - the question was in answer to JT's post (the clue is - that's why I quoted his text) which he did not send to me via PM - ok? I would actually prefer to hear from him when he is ready.

Let me try again - Quality Time need not reply - JT - what about the travelling public and crew and the poor hill walkers on the lump, since we all recognise that (a) (i) is ideal but not universal, (b) (i) is extremely unlikely and (b) (ii) is extremely common? Who's problem is it then? Is that not the issue? Are the regulators being thorough enough in this age of SMS and self-regulation?

[Quality Time]

Oh dear - what we have to deal with!

Don't patronise me BOAC.

The question was not directed specifically at JT.

Please post a list of those you consider worthy of taking part here - might save us mortals some time and effort in future!

[john_tullamarine]

What about the travelling public and crew and the poor hill walkers on the lump,

This is why these sorts of things ought to be discussed periodically on PPRuNe .. the reality is that there are elements within the Industry which simply do not do a reasonable job at meeting their sensible obligations .. forget about what the black and white of the rules might be. Is it not sensible to do whatever is reasonable to keep the CFITs at bay ? Many of us can cite numerous instances of pilots AND operators knowingly (but often in ignorance) sidestepping their responsibilities.

since we all recognise that (a) (i) is ideal but not universal,

regretably true.

I have had a number of ops eng mates in various airlines tell me unsettling stories of quite unacceptable philosophical policies.

Maybe I'm just a nervous nellie and the other fellow is being reasonable, if accepting a much higher inherent risk ? Ask me, or OS, whether we ignore or attend to the failure case all the way up to a safe height when doing ops engs things ? Maybe both of us are just far too conservative for our own good ?

(b) (ii) is extremely common?

.. and is that not a major concern to all of us ? Keep in mind that the guys and gals in the pointy end are the first to arrive at the scene of the accident ...

Who's problem is it then? Is that not the issue?

[Putting the passenger to one side - his/her only means of exercising control (for the small proportion of passengers who might have any idea of the underlying matters in question) is to vote with the feet.]

First and foremost, it's the commander's problem. However, that is a facile observation as it is simply not practicable for the typical pilot to do the sums. Therefore it must be the operator's problem. The thrust of the argument must revolve around corporate responsibility, liability and obligation.

Are the regulators being thorough enough in this age of SMS and self-regulation?

The Regulator comes a distant third and, really, can only do the audit thing in arrears. Sadly, some regulators appear not to have enough technical competence in house to be able to audit competently in the first place ...

There is an 'acceptable' fatal accident rate in all forms of transportation - (bad luck if you happen to fall into it)

Indeed .. and aviation certification philosophy talks in terms of orders of risk within the design, certification, and manufacturing processes. The problems escalate (in respect of the present thread's subject matter) when the pilot is unable, and the operator unwilling to address and meet the risk requirements inherent in the regulatory process.

Would you try to return to the company procedure track if safe means to do so exist? Yes, I meant this

Fine sentiments .. but, as before, what does it mean and how do you measure it ?

...there are "such" carriers that does not have the required procedures, analysis and whatever. What's left to do in that case?

Unfortunately there is no simple answer...

(a) operational personnel ought to exercise pressure.

Individually, this is a nonsensical wishlist due to the authority gradient but, in such cases as we see where unions have some strength such group pressure can be effective.

For instance, the Australian domestic arena, up until the mid-80s, was one such example where the relevant union was able to work fairly co-operatively with the operators .. but had the Industrial 4-by-4 lump of timber in reserve should that be necessary. I can't speak to the International group but, given that QF's ops engineering folk were both highly professional and well-integrated within management decision systems, the result was much the same.

(b) the operator's Board-equivalents ought to be questioning and testing the executive areas .. at the end of the day, both are exposed to eventual legal redress. That this doesn't work in all cases does not reduce its philosophical and corporate importance.

(c) the Government ought to be addressing its Signatory obligations through its delegated Regulator. We could talk all day about the strengths and weaknesses of any given Regulator.

What does this mean ? .. and how does the pilot measure it ? I had in mind something like being in VMC, no significant obstacle towards the EO procedure

Sounds good. However ...

(a) VMC generally is not a useful option for two reasons -

(i) commercial (and heavy military, for that matter) operations are conducted by day/night, and often in adverse met conditions so the eyeball strategy lacks routine credibility

(ii) for most heavy aircraft (and the typical light twin, for that matter) the OEI body angle after takeoff precludes the pilot's being able to see where he/she is going.

and, for the OEI case, eyeballing shallow gradients and estimating clearances is pretty well an impossible task.

no significant obstacle

Ah .. this is an oft-raised possibility. Problem is how do you decide whether a given obstacle is significant or, indeed, the critical obstacle for the section of the departure ? Without doing the ops eng sums, it is just not a feasible routine strategy. Even in the case of a single, isolated obstacle, that obstacle may either be critical or, indeed, of no real significance to the published procedure.

Caveat - sometimes we (as ops engineers) impose a requirement for the PNF to sight a particular obstacle as a marker during an escape procedure but that is a whole different ballgame to routinely asking the crew to wing it after the noise reduces ...

Don't patronise me BOAC.

We all understand that sometimes discussions can get a bit focussed. However, reasonable comments or friendly banter ought to be taken in our stride. As always, a good tactic is ten deep breaths and a cup of char before reacting .... we (ie all of you good folk, including me), as the PPRuNe thread discussion stakeholders, need and should seek input from the widest possible group of technically competent folk .. so we must, necessarily, be able to tolerate a range of styles and presentation in order to achieve that wider goal.

[stator vane]

was deep within the flight manual of the 738 that i was able to look through whilst at the former excellairways in gatwick.

the title of the page, was performance enroute climb one engine inoperative 2 a/c packs on flaps up.

the lowest pressure altitude was 4000 feet. one can look down at the bottom at the outside temp-go up to the 4000 feet line and cross over to a gross weight set of lines-example-23 degrees C 4000 feet p.a. crossed the 68000kg line giving 1100 feet per minute rate of climb

i have not been able to access that chart anywhere else.

[john_tullamarine]

All flight manuals for heavies will have similar data, usually associated with drift down procedures.

[Ocampo]

Well, again, thank you very much (for being so patient with me while explaining your points of view about my questions :))

So, if I understand you correctly, the best option (considering "normal" operators, set of conditions, "decent" design of the procedures) would be to follow the procedure...

However, based on what I've read, I will simply agree with you on

Unfortunately there is no simple answer...

Thank you and best regards

[BOAC]

Thanks for a full reply, John - I guess we can summarise it with 'Caveat Emptor'? Certainly my policy.

[john_tullamarine]

So, if I understand you correctly, the best option (considering "normal" operators, set of conditions, "decent" design of the procedures) would be to follow the procedure...

Providing that the procedure is competent. Unfortunately, there are operators who don't do the "right" thing and there are many operators where the engineering folk do the thing with an engineering hat on but without any useful operational input.

The ideal arrangement is to have a competent engineering group with some operational folk involved or, where it sometimes happens, to have folk who wear both hats .. which includes such folk as OS, mutt, and me ...

Those who spend time in the sharp end tend have a healthier respect for the realities of operations.

This is not to say that the work is difficult .. on the contrary it is straightforward .. requiring, in the main, only a modest technical competence and a good attention to housekeeping and detail.

If the procedure is not competent then you start to head toward no-mans-land. It helps if the pilot has a basic competence in the discipline (ie something along the lines of the old Performance A training).

Main thing is to get the message across that running on a wing and a prayer is not a good life strategy when it comes to engine failures during takeoff.


I guess we can summarise it with 'Caveat Emptor'?

you betcha, good sir.