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I ask as a dilettante, so please feel free tocorrect or emend this.

Please mind that https://www.youtube.com/watch?v=ryIbpHkeK2U is a video that's curiously and strikingly mirrored and in reverse view, as cautioned by the comments.

Around 4 mins 3 secs into the video, the captain pushes forward the throttle. Afterwards, he removes and hoists his hand from it, to push a button atop that changes an instrument display,
from showing the tail view (camera) of the aircraft (to assist with taxiing???),
to the primary flight display.
Subsequently, he replaces his hand back atop the throttle.

Why doesn't he push the button before deciding to takeoff and set takeoff thrust? Isn't the foregoing process more dangerous? For example, if the decision to abort happens exactly when no one's hand controls the throttle, then precious, exigent seconds would be wastd?

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You do know that unlike the throttle on a car or motorcycle, the throttle lever on an aeroplane stays put where it is set to, right? –  RoboKaren Jul 30 at 17:53
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@RoboKaren ...nonetheless the standard procedure in all aircraft I'm familiar with is to keep your hand on the throttle in the event you need to yank it back for an abort. –  voretaq7 Jul 30 at 18:05
    
I know but wasn't sure if the OP knew either how the throttle worked or what the protocol was. –  RoboKaren Jul 30 at 18:06
    
He probably realized that his MFD was still in camera mode when he looked down for airspeed. At which point he had to change it to PFD mode because the airspeed tape is essential. –  Justin Kiang Aug 1 at 19:15
    
@RoboKaren Thanks. I do, yes. –  Law Area 51 Proposal - Commit Aug 3 at 15:11

2 Answers 2

up vote 5 down vote accepted

Actually he does push the button before selecting takeoff thrust.

Often1 the procedure on jets during take-off is to move the thrust levers about half way, wait for the engines to spool up and only then select TO/GA or Flex thrust as desired. In the video the pilot switches the display during this intermediate step. So the engines are not even spooled up yet and the aircraft is still moving slow. Plenty of time to stop if anything fails.

In fact even when nearing v₁ the reaction does not need to be that fast. The calculation of v₁ includes 2 s reaction time and correct response is more important. Look e.g. on this training video (it's A330, not A380, but the procedure is the same). The reaction is not that fast; they only retard the throttle after checking and calling the fault ("engine fire").

1It used to be that the engines could flame out if you added fuel too quickly, but that's no longer the case now when engines are managed by FADEC (full authority digital engine computer). Some manufacturers/airlines/pilots maintain the procedure, most likely to avoid applying full power if one of the engines manifests some problem early. Or at least the pilot in this video does it.

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On the emb145 you advance the thrust levers from idle straight into the detent with no need to pause. The FADEC handles a smooth spool up to the selected takeoff thrust setting. –  casey Jul 30 at 21:15
    
@casey: Hm, it seems (from checking various cockpit videos) that the procedure is sometimes used and sometimes not and it does not seem consistent even for single aircraft type. Of course the original reason that the engine might flame out if fuel is added too quickly does not apply to engines controlled by FADEC, but it seems some keep the procedure to avoid asymmetric thrust (which isn't much concern in EMB-145 with tail-mounted engines) in case one engine lags behind or manifests some problem. –  Jan Hudec Jul 31 at 8:16

This is completely normal in Aircrafts like the A380 , Boieing 777 etc . Hands off at V1 (Engine failure recognition speed) is perfectly proper in an aircraft with multiple engines.

The throttles still moves , however the power setting (EPR) is in the computer and the precise setting of the engines is automated. The Pilot Flying the aircraft will still feel the throttles vibrating under his hand, but it's the auto throttle doing it, and not the flight engineer.

If Auto thrust is engaged, then there are 3 detents - Climb, Max Continuous/Flex and TOGA. If Autothrust is not engaged (at any time in the flight) then the thrust levers work just like the T/Ls on any other aircraft.

During take off, the T/Ls are placed either in TOGA (Take Off/Go Around) if the pilot is doing a max power T/O, or in Flex/Max Continuous detent if the pilot is doing a Flex power T/O. When the levers are in either of these detents the FADEC (Full authority digital engine control) will give the aircraft the max power available for that selection (It depends on the ambient conditions). When the aircraft reach the Thrust Reduction altitude the pilot may choose to move the levers backwards to the Climb detent, and will then get Climb power. The levers remain in this detent until the pilot reduces thrust to idle in the flare during the landing . This means that the FADEC will give the aircraft whatever power is necessary to achieve what you are trying to do - climb power for the climb, or whatever thrust is necessary to achieve your cruising Mach number, or desired rate of descent or whatever.

If an engine fails, then the levers on the remaining engines are moved back into the Flex/Max Continuous detent, and the aircraft will get Max Continuous power. If the pilot has to do a go-around at the destination, the pilot puts the levers into the TOGA detent and the aircraft will get all the power available.

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In Airbus the throttles don't move. They don't have any servo for it. They are placed in the detent (TO/GA, MCT/FLX or CLB), which is a fixed position on Airbus, and FADEC does it's thing. –  Jan Hudec Jul 30 at 20:22
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But you are not answering the question anyway. The question is about the very beginning of the take-off roll where pilot flying selects 50% power and then moves his hand off to switch his primary display and back. –  Jan Hudec Jul 30 at 20:26
    
The question posed was related to the YouTube video and all that the asker wanted to know was is this tactic normal or is this a departure from normal conventions ? I have answered the question with the very first sentence of my [above] comment . –  D_S Jul 31 at 17:46
    
No, you said "Hands off at V1" and the question is about hands of at the very beginning of the take-off roll. –  Jan Hudec Jul 31 at 19:16
    
Hands off before V1 is possible in aircrafts like the A380.Once the throttle is advanced to the FLEX indent and A/THR is engaged the Engine Display should reflect " Power Set" . At this point it is ok if the pilot takes his hand off the throttle . –  D_S Jul 31 at 19:46

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