Accelerating to Vfto on single engine climb

[globaltrainer]

Hi,

When accelerating to Vfto (Vfs) after a V1 cut, do you guys teach to lower the nose or to level off?

Boeing 737 FCTM, as far as I recall, recommend lowering the nose significantly while preventing the a/c from descending. Hence, a very light rate of climb (100-200 fpm) is permitted as opposed to pressing ALT and allowing the a/c to balloon in order to capture the altitude selected when pressing ALT.

What is your opinion? References would be greatly appreciated.

Cheers

[RAT 5]

If I remember correctly, the performance calculations assume level flight. I did fly for one operator who did not trust this new failed TOGA mumbo jumbo and used V/S to clean up on a normal day. Engine failure, of course they used ALT HLD.
Boeing TOGA FD will give level flight or up to 200fpm ROC. It will not allow descent. Hot high, heavy weight, max ATO thrust etc. will give 0'fpm ROC. Any excess thrust will allow a breath of a climb.

[Centaurus]

If I remember correctly, the performance calculations assume level flight

That should ensure the aircraft reaches clean manoeuvre IAS within the five minute take off power limit. If not using the FD, fly attitude to maintain zero rate of climb while accelerating to flaps up speed. Boeing 737 FCTM recommends auto-throttle disengaged if on one engine.

[john_tullamarine]

The aim is to arrive at the final clean speed as the flap finally retracts. The requirement is not worse than level flight but how to do it best for a given aircraft will be prescribed in the AFM.

While deferring to Centaurus (who has about a gazillion times more 737 experience than I), I seem to recall that the idea with the 737 was a shallow climb to avoid over running the clean speed during the retraction sequence.

[Broomstick Flier]

Here, 767 operator, we are taught to accelerate with positive ROC until clean-up. This ROC should be, initially, around 200fpm and then you can adjust it (up or down, limited to level flight) according to the actual performance (i.e. light vs heavy load)

[GlenQuagmire]

We aim to fly the second segment at V2+20. At 1500 aal we wind the speed up to VFTO and the flight director commands between level flight and a very shallow climb while we accelerate. Personally, i am not a fan of using alt because a genuine engine failure is an adrenaline inducing event and its neater to keep the engine failure scenario as close to the all engine scenario as possible. I cant imagine it makes a lot of difference from an achieved profile point of view. If you balloon a tiny bit using alt hold so what - youre still at max chat on the remaining engine so from the point of view of the total energy in the system it must be about the same. The fewer buttons you push and the simpler it is the better in my view

[Judd]

Relying on flight directors is SOP nowadays with todays pilots going straight from a single or light twin into the RH seat of a jet transport. Some argue that flight directors can have the unfortunate side effect of degrading basic instrument flying skills needed for accurate instrument flying; particularly hand flying. Blind concentration on trying to follow two needles and keep them centred has often caused pilots to "chase" the needles.

So when you are relying 100% on the FD indications to maintain (say) level flight or slight rate of climb during the third segment clean up, chasing the needles while handling an emergency can cause less than optimum acceleration towards clean speed. Now, add limiting terrain or an obstacle at the end of the clean up segment or perhaps even further down the take-off track, it behoves the pilot to reach flaps up clean speed as soon as practical in order to achieve greater obstacle clearance.

If simulator observations are to be relied upon, unless the autopilot is flying the aircraft, pilots can rarely fly the FD needles without occasional "chasing" especially in the roll mode with engine failure and inevitable over-controlling on the rudder pedals.

Those pilots fortunate enough to be allowed by their company to maintain raw data manual flight skills, can often find these skills are handy to fall back upon for maintaining accurate asymmetric flight during the clean up phase. It is no big deal for them, since they find scanning the primary artificial horizon, altimeter, ASI and VSI more efficient and easier, than the intense concentration needed to fly the FD. Thus the pilot maintains better awareness or the "big picture" as against relying on FD needles to the detriment of situational awareness.

Apologies for thread drifting into raw data v flight director age old discussion.

[john_tullamarine]

We aim to fly the second segment at V2+20

.. but not if the failure occurs at a lower speed, one trusts ?

[RAT 5]

Judd: I hope you are not advocating switching off the FD's during an engine failure clean up. Thee is no need to 'chase the needles' if the training has been correct. I'm old school and can look through the FD and still scan the raw data performance instruments. This leads to delicate breaths on the controls, not chasing with agricultural inputs.

Following FD accurately does require self discipline. I found it disappointing to see cadets sitting just under the pitch bar, thinking they were doing OK, but IVSI was 1-200fpm ROD. They were not x-checking. That is training at basic entry level and is missing.
During the acceleration there is need for continuous delicate trim adjustment in elevator and in rudder application. This is where the IVSI & TK Line can help you freeze the FD's. Lead not follow.

[Centaurus]

I'm old school and can look through the FD and still scan the raw data performance instruments.

I envy those who can "look through" the FD. I find the needles obscure the "little aeroplane" and are distracting. My preference for engine failure is to initially fly the un-cluttered standby AH and eventually the FD needles on the PFD come together nicely. Horses for courses

[RAT 5]

Centaurus: what I meant was, perhaps, not literally look behind/through the FD as that gives only bank angle & attitude. My meaning was to scan the IVSI, ASI & TK Line. This would help me finesse the trim adjustments in pitch and rudder input to stop the FD from departing the middle box. Anticipate the changes required. Look 'around the FD' might be a better expression.
I envy those who can see the SBY AH with accuracy.

[globaltrainer]

Originally Posted by john_tullamarine

The aim is to arrive at the final clean speed as the flap finally retracts. The requirement is not worse than level flight but how to do it best for a given aircraft will be prescribed in the AFM.

While deferring to Centaurus (who has about a gazillion times more 737 experience than I), I seem to recall that the idea with the 737 was a shallow climb to avoid over running the clean speed during the retraction sequence.

I remember the same.

[H Peacock]

I'm with GQ; climbing in FLC so just walk the speed bug up to Vfto when passing the acceleration altitude. If you walk the speed up slowly you keep a greater RoC while you accelerate. Probably FLC at its most useful.

Not too sure how you judge arriving at Vfto as the flaps finish retracting. Not a good time to be on the wrong side of the drag-curve if you misjudge it!

[GlenQuagmire]

Originally Posted by john_tullamarine

We aim to fly the second segment at V2+20

.. but not if the failure occurs at a lower speed, one trusts ?

No - but I was primarily replying to the original posters question regarding the the technique we use to transition 2nd to 3rd segment. That said, if I wasnt climb gradient limited I would certainly be happier at V2 + 10 to V2 + 20 as my particular plane isnt very nice at V2. If I was having any kind of control difficulty (for instance its not a nice clean sim type flameout but was kicking and banging around) I am pretty sure I would try to accelerate to +20. Also, the reduction in the necessary amount of rudder is very noticeable in that 20 knots so I would think the reduction in drag, and therefore improvement in climb, is also significant. I cant do the maths any more as I stopped being an engineer 30 years ago.. dunno really, lets see how it goes when we eat some birds eh!

[Centaurus]

That said, if I wasnt climb gradient limited I would certainly be happier at V2 + 10 to V2 + 20 as my particular plane isnt very nice at V2.

In the old days if an engine failure occurred beyond V2, the technique was to pitch up if necessary to revert to V2. This was because the obstacle clearance gradient was based upon climbing at V2 following an engine failure.
This policy was changed after an American Airlines DC-10 crashed shortly after take off from Paris. Briefly, a wing engine fell off its pylon shortly after lift off. As the aircraft was accelerating, the crew did not know initially the engine had gone. Damage was caused to the leading edge slats on that side causing them to retract while the slats on the other wing remained extended.

At the speed the DC10 had reached shortly after the engine fell off, the aircraft was controllable even with its slats on that side coming in due loss of hydraulics. . However, when the crew reduced the speed back to a V2 as per company policy at the time, and the left wing slats fully retracted, the crew were unable to maintain wings level. The aircraft rolled almost inverted and crashed. See report:
Lessons Learned

Later flight tests revealed there was negligible loss of climb gradient between climbing at V2 and climbing up to V2 plus 25 knots. Thus if the crew of the DC10 had climbed at the same speed it had attained after the engine fell off the wing, controllability could have been maintained and the accident averted. Manufacturers amended their AFM accordingly.