Both hands on flight controls after V1 - tradition, myth or technical fact.
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Both hands on flight controls after V1 - tradition, myth or technical fact.
It is generally accepted wisdom that the PF should keep one hand on the thrust levers during the latter part of an automatic approach with auto-throttles engaged. Presumably this is because of the remote possibility of an auto-throttle malfunction.
That being so, why is the PF required to remove his hand off the thrust levers at V1 in order to rotate with both hands and therefore run the same risk as above of an auto-throttle malfunction. What is the perceived problem of conducting a one handed rotation and having the other hand guarding the thrust levers? Is the two-handed rotation a mere tradition in the airline industry, or is there a technical reason. And please don't say it is because it's easier to keep the wings level...
That being so, why is the PF required to remove his hand off the thrust levers at V1 in order to rotate with both hands and therefore run the same risk as above of an auto-throttle malfunction. What is the perceived problem of conducting a one handed rotation and having the other hand guarding the thrust levers? Is the two-handed rotation a mere tradition in the airline industry, or is there a technical reason. And please don't say it is because it's easier to keep the wings level...
One reason I can think of to remove your hands from the thrust levers after V1, is to avoid retarding them; i.e. rejecting the take off.
Another the rotation rate required on some aircraft needs some precise handling to avoid a tailstrike.
Another the rotation rate required on some aircraft needs some precise handling to avoid a tailstrike.
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My guess is, as with most things in aviation, it all started before the days of automation. I would want to believe that before autothrottles came into being, the PF would have his hand on the control column after rotation, while the PNF and/or FE would have his hand of the power levers/thrust levers/throttles and monitering engine parameters. Thinking back to flight school, I remember being taught to keep a hand on the throttles during initial climb out to prevent them from being retarded due vibration.
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After V1, your hands should be nowhere near the throttles, to help prevent any reflex action involving the throttles, until a safe height is reached. So if you are operating an aircraft with a yoke, then grab the other "horn."
There maybe an exception to this, in the event of a double engine failure on a 4engined heavy a/c just after V1.
I also stand to be corrected!
There maybe an exception to this, in the event of a double engine failure on a 4engined heavy a/c just after V1.
I also stand to be corrected!
Aren't most autothrottles 'clamped' above a certain speed if engaged in T/O mode (actuators freeze, A/T reverts to armed for mode change after T/O)? A failure in the A/T logic would not lead to power changes in that case.
Hands are off the throttles above V1 to prevent PF from making inadvertent power changes, especially retarding them in case of engine failure above V1.
Hands are off the throttles above V1 to prevent PF from making inadvertent power changes, especially retarding them in case of engine failure above V1.
Moving one's hand from the thrust levers at V1 is symbolic in nature; it symbolizes that the point has been reached, previously decided before initiation of the takeoff run, at which the airplane is going flying should an emergency arise. Removing one's hand from the thrust levers is a form of commitment to the remaining takeoff; one is setting aside the decision to retard the thrust levers, and has committed to flying the airplane off the ground.
Keeping your hand on the thrust levers during an approach isn't merely for the sake of an autothrottle malfunction. In the event you need to continue the approach or make changes to the approach, you're the person manipulating those thrust levers. You're not so much guarding them in case the autothrottle suddenly retards them; you're there to take over, and at some point you will take over. In effect, you're doing the opposite of what occurs on the takeoff. On the takeoff, you have the thrust levers until the aircraft takes over (for those of you who use autothrottles for takeoff; I don't), or until the thrust is set for takeoff. On landing, if you are using autothrottles, the thrust is essentially set until you arrive at the runway (autoland excepted), at which point the airplane is given back to you.
On approach, the airplane has to do something; be it autothrottles of you, someone has to be manipulating that thrust lever all the time. On takeoff, conversely, the thrust is set at max or reduced, and you're not managing the approach angle at all, and your airspeed is manipulated by pitch. Set the thrust and go. Not until your initial thrust reduction during a standard noise abatement departure and then setting thrust later in the same procedure, do you again touch them. Not so for the approach and landing; the thrust levers are constantly being adjusted, or at a minimum gaurded to make an adjustment should it become necessary, either by you or the airplane.
Keeping your hand on the thrust levers during an approach isn't merely for the sake of an autothrottle malfunction. In the event you need to continue the approach or make changes to the approach, you're the person manipulating those thrust levers. You're not so much guarding them in case the autothrottle suddenly retards them; you're there to take over, and at some point you will take over. In effect, you're doing the opposite of what occurs on the takeoff. On the takeoff, you have the thrust levers until the aircraft takes over (for those of you who use autothrottles for takeoff; I don't), or until the thrust is set for takeoff. On landing, if you are using autothrottles, the thrust is essentially set until you arrive at the runway (autoland excepted), at which point the airplane is given back to you.
On approach, the airplane has to do something; be it autothrottles of you, someone has to be manipulating that thrust lever all the time. On takeoff, conversely, the thrust is set at max or reduced, and you're not managing the approach angle at all, and your airspeed is manipulated by pitch. Set the thrust and go. Not until your initial thrust reduction during a standard noise abatement departure and then setting thrust later in the same procedure, do you again touch them. Not so for the approach and landing; the thrust levers are constantly being adjusted, or at a minimum gaurded to make an adjustment should it become necessary, either by you or the airplane.
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In the company I work for, the captain keeps his hand on the thrust leavers until V1 because in the event of an RTO, it’s him that stops the aircraft. As far as I’m aware, the captain’s hand comes away from the leavers at V1 so that there is no reflex reaction to stop the aircraft after V1 should something go bang. It removes the temptation to try and stop, when the decision has already been made to go, that’s my understanding of it anyway. 
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AT systems used during take off must have a safety feature such that at fault will not change the thrust. Hence "HOLD" mode. Even if the AT system goes haywire it cannot change the thrust.
May be called something else on each type but is active from about 60kts to 400ft.
May be called something else on each type but is active from about 60kts to 400ft.
Bottums Up
Take-off, auto throttle at set take-off power, not modulating.
Approach (B717), auto throttle modulates until flare (30') when they retard to idle.
Hence, guard them on approach but at V1, remove the temptation to suddenly retard them if there's a big bang.
Approach (B717), auto throttle modulates until flare (30') when they retard to idle.
Hence, guard them on approach but at V1, remove the temptation to suddenly retard them if there's a big bang.
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All fairly well the same responses...
Boeings have a "Throttle Hold" function that unpowers the A/T actuators at a set point during the takeoff roll.
For the 737NG it is at 84 knots, and the FMA reflects that change.
After that, for the rest of the takeoff, the throttles are totally manual!
If you're a bit slow getting the thrust up to spec, at 84 knots the throttles will stop advancing, manual input is then needed.
Since most V1s are well in excess of 84 knots, removing one's hand from the throttles at V1 is not a problem!
But, if you abort before 84 knots, and 'as you do' retard the throttles to idle and beyond, the autothrottle will still be trying to advance to the selected takeoff power setting. But above 84 knots, will not!
This is why we select disconnect of autothrottles for every abort, then that's one thing you don't have to think about.
Normal ops for us!
Cheers...FD...
Boeings have a "Throttle Hold" function that unpowers the A/T actuators at a set point during the takeoff roll.
For the 737NG it is at 84 knots, and the FMA reflects that change.
After that, for the rest of the takeoff, the throttles are totally manual!
If you're a bit slow getting the thrust up to spec, at 84 knots the throttles will stop advancing, manual input is then needed.
Since most V1s are well in excess of 84 knots, removing one's hand from the throttles at V1 is not a problem!
But, if you abort before 84 knots, and 'as you do' retard the throttles to idle and beyond, the autothrottle will still be trying to advance to the selected takeoff power setting. But above 84 knots, will not!
This is why we select disconnect of autothrottles for every abort, then that's one thing you don't have to think about.
Normal ops for us!
Cheers...FD...
Judging from the replies to the question there is no compelling technical reason for the pilot to use both hands for rotation (see Airbus sidestick). That leaves tradition and myth. Taking your hand off the throttles just in case you succumb to a reflex action of jerking them back if you get a fright, suggests a myth. Like the reflex action of slightly lifting your bum off the seat when you know the other pilot is about to bash the Boeing on the bitumen. "Bit late on the flare, Bloggs...."
Different I believe if you are being shot off an aircraft carrier where the enormous power of acceleration can cause you to pull back the throttle(s) - hence hand is kept at the back of the throttles and not on them.
That leaves tradition. And tradition is just another name for someone's personal opinion years back.
Verdict: One handed rotation is perfectly safe - it's done every day on light twins and singles.
Different I believe if you are being shot off an aircraft carrier where the enormous power of acceleration can cause you to pull back the throttle(s) - hence hand is kept at the back of the throttles and not on them.
That leaves tradition. And tradition is just another name for someone's personal opinion years back.
Verdict: One handed rotation is perfectly safe - it's done every day on light twins and singles.
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That leaves tradition and myth. Taking your hand off the throttles just in case you succumb to a reflex action of jerking them back if you get a fright, suggests a myth.
PP
factual error management procedure
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Centaurus- so you are saying that it would be acceptable to leave your hands on the thrust levers past V1? Many an aircraft has gone off the end of the runway because of a post V1 abort.
Don't worry, Centaurus is from Australia...
I use two hands because I'm a weakling, but mainly because it gives me better pitch-rate control during the rotation.
And if you don't have your hands on the throttles after V1, there is very vey little temptation to re-grab them after a big bang before liftoff, as previously mentioned.
I use two hands because I'm a weakling, but mainly because it gives me better pitch-rate control during the rotation.
And if you don't have your hands on the throttles after V1, there is very vey little temptation to re-grab them after a big bang before liftoff, as previously mentioned.