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Assuming a typical transport-class aircraft, what would the pilot do if the aircraft does not have a positive rate of climb immediately after takeoff?

Would the pilot just lower the nose to pick up airspeed, then raise it back up once they’re satisfied? Or maybe retract the flaps a bit? Assuming the throttle is at 94% N1, would applying full throttle at that point even stop the decline in speed?

Jon Story
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George Clooney In a Mooney
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    They would go to crash site first. – vasin1987 Oct 25 '19 at 06:55
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    Why is your question directed to the B737? The answer applies to ALL aircraft. It seems you are digging for dirt where there is none to be found. – Mike Sowsun Oct 25 '19 at 13:40
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    @MikeSowsun not digging for anything. Just learning dude. Sorry you take it the wrong way. – George Clooney In a Mooney Oct 25 '19 at 16:48
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    This is an absurd question... the jet will have a positive rate of climb even with one engine out. The 737 has more than ample thrust to have a highly positive rate of climb immediately after takeoff. If you've lost an engine, you deal with that (while climbing). If you're in windshear, you'd use those procedures. But if you rotate & don't get a positive rate, it's because your pitch attitude is too low, so *raise the nose* to a normal attitude, and you'll climb away just fine. – Ralph J Oct 25 '19 at 23:00
  • I only added 737 because I’m not sure if other aircraft have different procedures for this. And I’m specifically interested in the 737 – George Clooney In a Mooney Oct 27 '19 at 05:07
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    @RalphJ There have been quite a few accidents with planes not gaining altitude after lift-off: USAir 405, Air Florida 90, almost all of which had to do with incorrect de-icing prior to takeoff. – JZYL Oct 27 '19 at 19:57
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    Hail Mary, full of grace . . . – Mike Brass Oct 29 '19 at 00:54
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    @RalphJ If you’re too slow or heavy, say because of pitot issues or incorrect performance or weight and balance, then lowering the nose would be correct rather than pulling. – Cpt Reynolds Dec 16 '19 at 22:19

3 Answers3

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The first thing I would do is advance thrust to maximum available thrust, make sure both engines are indeed operating. Next I'd check is if the speedbrake is stowed.

I would not consider retracting flaps because when you are too slow to climb you are definitely too slow to retract flaps... could be deadly.

Normally this kind of situation can't happen unless you have at least one engine failure and the remaining engine not working at full thrust or the wings are contaminated with ice or snow. The aircraft is perfectly capable of climbing on one engine, so if you have two engines on max takeoff power and are still not climbing then something is seriously wrong. In case of ice/snow on the wings, well there is not much you can do about that in the air, put on wing anti ice and hope that it is quick enough to clear the wings of any contamination, this comes at a penalty of losing precious thrust because of the bleed air extraction. This situation is usually avoided by removing snow and ice from the wings whilst still on the ground - before taking off.

Jan
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This sort of scenario happens from time to time. Before a flight the crew will calculate the flap setting and speed at which the aircraft rotates based on aircraft weight, the weather conditions, and runway length. If any of these are entered incorrectly, the aircraft could rotate too soon and not lift off when expected.

To decrease wear on the engines, modern jet airliners will often use less than full takeoff thrust. If the crew finds the aircraft is not accelerating or lifting off as expected, they can increase the thrust to the full takeoff setting. This is probably the first thing to check as it's a quick and easy step that would help get the aircraft up to the necessary speed and in the air faster.

It's very unlikely that a crew would decrease flaps in this situation, as this would decrease the lift, and thus take even longer for the aircraft to lift off. There have been several crashes where insufficient flaps were suspected as a contributing factor, causing the airplane to not lift off as expected and making it more difficult to control at low speeds. The crew might actually increase flaps to lower the speed needed to lift off.

The crew may also decide to to reject the takeoff. By the time an aircraft is rotating, there may not be enough runway left to stop safely, so the crew must make a quick decision as to what the safest option is.

fooot
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First I would check on PM for pilot incapacitation as it might be the first cause. Then, if the plane is indeed not climbing if because something was totally wrong. Even with one engine failure you are supposed to have a positive rate of climb on the 1st segment and 2.4% on the 2nd segment. Make sure the trust setting is correct. Retracting the flaps would cause you to sink at this moment.

FONSPA
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  • This does not provide an answer to the question. Once you have sufficient reputation you will be able to comment on any post; instead, provide answers that don't require clarification from the asker. - From Review – Jpe61 Dec 17 '19 at 16:42
  • Why not? I answered my first go-to would be to check the PM! You shouldn't care too much about virtual reputation. My reputation is the +6000h as a jetliner Captain. – FONSPA Dec 17 '19 at 17:43
  • Oh, @FONSPA this is interesting. I'm damn sure I have not reviewed your answer, that's some weird bug in the system. Regarding your answer: why would you check on PM for incapacitation? You'd be the PF, so PM would be handling comms, right? You are, ofcourse, spot on with the rest of the answer. – Jpe61 Dec 17 '19 at 18:10
  • My answer is not applicable to all types of Aircraft/Operations. On a multi-crew airplane, the PM will be the one calling for a positive rate/climb. If he doesn't, maybe he is incapacitated or distracted. If it is the actual airplane that is not climbing then the second part of my answer applies. I also remembered that in some places there is a lot of cheating and people are paid to put extra cargo in the cargo hold without the extra weight being accounted for. It happened to me in Asia when we used to have 2 loadsheets. The official one and the real one... – FONSPA Dec 17 '19 at 19:02
  • As PF you have your own gauges to verify positive climb. If your gauges do not show positive climb, most likely PM's gauges will not either. So if you've rotated -> no positive climb on your gauges, apply full throttle and check speedbrake (as stated in previous answers) + possibly something else from your memory items. The condition of PM and pos. climb callout are totally secondary and have no immediate effect on the matter whatsoever. – Jpe61 Dec 17 '19 at 19:32
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    I thought you meant the PM might have collapsed over the control column after the incapacitation. –  Dec 18 '19 at 13:10
  • @ymb1 isn't that why pilots wear a shoulder harness, to prevent collapsing onto the controls? (Or, at least some of the reason) – FreeMan Dec 19 '19 at 18:44
  • Jpe61 as a PF during takeoff roll I'm looking outside 90% of time and PM the opposite. Of course, if the problem is not about positive rate call but instead of the plane not actually climbing that's a different story. – FONSPA Dec 20 '19 at 17:49
  • Jpe61, be careful when you say "Apply full throttle"! If you do that on a derated takeoff you might kill yourself! Instead, you should say "Apply maximum available thrust". When you derate your maximum available thrust is less than full throttle and by doing so might lose control of the airplane because the VMCG for derating is different than full throttle. Check speedbrake? Ok...but speedbrake is checked on TOGA with takeoff warning. Memory items? There are no memory items for this! So in effect your answer doesn't add anything and doesn't solve the problem – FONSPA Dec 20 '19 at 17:53
  • FreeMan, on the original Boeing 737 checklist do you know how many times are shoulder harness (or even harness) mentioned? Zero! You would be surprised with how many people forget them. – FONSPA Dec 20 '19 at 17:56