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]

SID or Engine failure procedure

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]

BOAC

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

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]

Originally Posted by JT

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.