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-   -   Rotation technique (https://www.pprune.org/tech-log/658534-rotation-technique.html)

stilton 8th Apr 2024 04:31

Rotation technique
 
From the first light aircraft I flew to heavy transport jets I was taught to rotate visually

At VR, check the airspeed then eyes go outside , judging the rotation rate by visual cues until you lift off then transitioning to an instrument scan with ADI as primary while checking airspeed and other instruments


In a low visibility take off that transition to instruments will be almost immediate of course



The only reason I mention this is I’ve been watching a few YouTube videos taken inside the cockpit, in almost every one the PF goes on instruments and stays on them the moment VR is called with the aircraft still firmly on the ground, not another look out the window until the autopilot is engaged

Thoughts and opinions

ScepticalOptomist 8th Apr 2024 06:57


Originally Posted by stilton (Post 11631202)
In a low visibility take off that transition to instruments will be almost immediate of course

I see no harm in doing the same thing each flight regardless of the visibility. If it works for a low vis takeoff, why not use the same technique all the time?

Prior to being on aircraft with HUDs I used the same technique you mentioned. Seemed to work pretty well.

Meikleour 8th Apr 2024 12:19

My experience of 4-engined aircraft (B707,B747,A340) versus the usual twin suspects shows that the rotation and unstick can be a lot less "dynamic" for example the B747 rotation used to tend to slow down at 10 degrees nose up attitude and needed a extra positive pressure to continue the rotation. Therefore one had to be aware of "tailscrape territory" more so than on a twin. Obviously this is more easily achieved by reference to the ADI!

As others have pointed out - why stare ahead into a black night sky or a foggy view.

Puts tinfoil hat on again!

deltahotel 8th Apr 2024 12:56

Don't think it's a twin thing. 75 and 76 both do this and it's to do with the tailplane going into ground effect, so the aim is a constant rate of rotation, varying back pressure to achieve that (and knowing that there will be a need to increase this at about that point in the rotation).

FLX/MCT 8th Apr 2024 13:14

I tend to keep my view outside as long as there are visual references making lateral tracking easier in case of strong x-wind or if an engine decides to quit. Once they‘re gone I go heads down.
I am convinced that this habit will make it easier once really required.
Almost all aircraft I have flown so far (all twins) show the „nudge“ around 10 degrees with the stabilizer in ground effect. For sure I will be scanning the ADI during this phase to allow a continuous rotation rate.

Considering the further climbout, I also noted that often the view is too much inside the cockpit in VMC conditions and somehow I note a lack of awareness for the airspace (classes) around. Sometimes colleagues are surprised to learn that the principle of see and avoid can also apply to IFR flights.

Vessbot 8th Apr 2024 13:26


Originally Posted by ScepticalOptomist (Post 11631250)
I see no harm in doing the same thing each flight regardless of the visibility. If it works for a low vis takeoff, why not use the same technique all the time?

​​​​​​Because the view outside provides far more angular resolution in attitude changes, allowing you to recognize them and react against them much earlier and remain more stable.

-------

I've also seen these videos that the OP refers to (1 or 2 were posted in the thread about that Emirates 777 that took off with a captured altitude at ground height and followed the flight director into not taking off, and hit an obstacle off the far end of the runway). And, when the PF looked (not glanced, but transferred 100% of attention to) at the PFD... had it been immediately after lift off, I would have been disappointed and annoyed at the complete automation dependence endemic in airline flying, that has come up here often as a topic.

But it wasn't merely immediately after liftoff, it was *on the ground* at the V1 call, or thereabouts. And so beyond disappointed, I was positively mind-blown gobsmacked. I wouldn't have believed it if I hadn't seen it. Who's steering the airplane on the runway in response to regular directional disturbances, crosswind gusts, etc? In response to an engine failure? There is just... nobody home.

Capn Bloggs 8th Apr 2024 13:32

So, not like this then (that's 29min 42sec in).



Vessbot 8th Apr 2024 18:32

Holy guacamole!

What do you think...
- OE student starts overrotating
- LCP says "not so much"
- OE student continues with "so much"
- getting close to tailstrike, LCP says "NOT SO MUCH!!!" simultaneous with pushing stick forward, which sums with student's continuing pull
- pull from student continues summing with push from LCP (both high deflection), after liftoff
- 2 seconds later, the "NOT SO MUCH!!!" finally processes into the student's brain, who lets go of the stick, and the LCP's forward push is the only remaining input
... plausible?

421dog 8th Apr 2024 18:39

“Rotating” in a single engine piston aircraft is commonly taught, but is a remarkably bad idea. A few extra kgs here or there can change ones whole perspective.
It’s pervasive, but it’s because the flight schools are teaching big-plane tactics to little-plane wanna be pilots.
”Levitation” in a little plane, is a much safer technique.


Vessbot 8th Apr 2024 20:00


Originally Posted by 421dog (Post 11631711)
“Rotating” in a single engine piston aircraft is commonly taught, but is a remarkably bad idea. A few extra kgs here or there can change ones whole perspective.
It’s pervasive, but it’s because the flight schools are teaching big-plane tactics to little-plane wanna be pilots.
”Levitation” in a little plane, is a much safer technique.

You're just substituting one word for another. Rotating simply means pitching up on takeoff from the nosewheel-on-ground attitude, that's it. Doesn't imply anything more specific about technique wrt. stick force, pitch rate, how much rotation is done before main wheel liftoff, etc.

421dog 8th Apr 2024 20:27


Originally Posted by Vessbot (Post 11631758)
You're just substituting one word for another. Rotating simply means pitching up on takeoff from the nosewheel-on-ground attitude, that's it. Doesn't imply anything more specific about technique wrt. stick force, pitch rate, how much rotation is done before main wheel liftoff, etc.

Not true at all..
in a 172, I hold a constant back pressure until the airplane starts flying. I absolutely do not “rotate” at a given speed.
On the other hand, in a big plane, with a real VR, I rotate as appropriate..

Vessbot 8th Apr 2024 21:48


Originally Posted by 421dog (Post 11631770)
Not true at all..
in a 172, I hold a constant back pressure until the airplane starts flying. I absolutely do not “rotate” at a given speed.
On the other hand, in a big plane, with a real VR, I rotate as appropriate..

Thanks for describing your rotation technique in the 172 (presumably, in use when it's not a gusty crosswind).

421dog 8th Apr 2024 22:45


Originally Posted by Vessbot (Post 11631806)
Thanks for describing your rotation technique in the 172 (presumably, in use when it's not a gusty crosswind).

look forward to seeing your blurb in accidents etc…

ScepticalOptomist 9th Apr 2024 01:50


Originally Posted by Vessbot (Post 11631535)
​​​​​​Because the view outside provides far more angular resolution in attitude changes, allowing you to recognize them and react against them much earlier and remain more stable.

Of course, as I said this is what I did too on aircraft without a HUD.
However, if my colleague rotated by coming inside to the PFD earlier than normal I would not have an issue with it as it is exactly what they have trained to do at night / low vis etc.

Trust the instruments is drilled in from a pretty early stage and I’d expect any of the crew i fly with to be able to rotate perfectly well on the PFD.


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