novice
Topic Author
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Signif Of The 40- To 100-knot Call During T/O Roll

Sat May 18, 2013 1:23 am

Abstract:

The 40- to 100-knot call during the T/O (Takeoff) roll is used to check the requirements that need to be established by the called speed. These requirements include

1.Directional control surface (vertical tailplane) starts to become effective with all engines operating.

2.T/O engine pressure ratio (EPR) should be set by this check speed so that the pilot is not chasing engine needles for a prolonged period during the T/O roll,

3.Cross-check the airspeed indicator gauges to ensure their accuracy and reliability.

In addition, type-specific requirements also might need to be established by the T/O roll check speed."



What is the T/O roll check speed?
What would be examples of specific type requirements that need to be established by the T/O roll check speed?

Thanks
 
26point2
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RE: Signif Of The 40- To 100-knot Call During T/O Roll

Sat May 18, 2013 2:19 am

40 - 100 knots is a wide range. I suppose somewhere in there we are expected to establish a standard call.

Our ops require an 80 knot call....pretty normal. Before this speed we can easily abort for anything but beyond it (and prior to V1) would only abort for "Red" items or loss of control.

Too many speed calls during takeoff can confuse the PF. His primary job, at the moment, is to decide if an abort is required. Too much chatter and information from the PM is a distraction.
 
BoeingGuy
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RE: Signif Of The 40- To 100-knot Call During T/O Roll

Sun May 19, 2013 1:55 am

Quoting 26point2 (Reply 1):
Our ops require an 80 knot call....pretty normal. Before this speed we can easily abort for anything but beyond it (and prior to V1) would only abort for "Red" items or loss of control.

80 knots is also when the two pilots are supposed to verify their Airspeed indications are 80, and when the Autothrottle goes into Throttle Hold (on a Boeing airplane). As the other reply indicated, about 80 knots the approved reasons for an RTO get much shorter.

Below 80 knots you can reject for stuff like a flight deck window coming open, tire failure, Caution message, etc. Above 80 knots it's only allowed for Engine Failure, any kind of Fire, Predictive Windshear warning (which itself is inhibited above 100 knots) or if the Captain judges that the airplane is not capable of safe flight.
 
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tb727
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RE: Signif Of The 40- To 100-knot Call During T/O Roll

Sun May 19, 2013 3:10 am

When I flew Lear 24's and 25's we had an airspeed alive, 80 knots, 100 knot then the V speeds. Those things accelerated so fast it was a mouthful and it came out like airspeedsalive80knots100acrosspanelsclear v1 rotate. I always felt it was a little overkill and a bit of a distraction.
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BoeingGuy
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RE: Signif Of The 40- To 100-knot Call During T/O Roll

Sun May 19, 2013 4:25 am

Quoting tb727 (Reply 3):
When I flew Lear 24's and 25's we had an airspeed alive, 80 knots, 100 knot then the V speeds. Those things accelerated so fast it was a mouthful and it came out like airspeedsalive80knots100acrosspanelsclear v1 rotate. I always felt it was a little overkill and a bit of a distraction.

What was the difference between the 80 knot call and 100 knots? I'm guessing 80 was for the change in reasons to RTO, and 100 was the airspeed check?

I've heard "Eighty" and I've heard "Eighty Knots, Throttle Hold" on Boeing airplanes. Throttle Hold is no biggie. Even if the Autothrottle Mode didn't change to Hold for some reason, guidance is to leave the autothrottle engaged and continue the takeoff as long as you don't have any other reason to suspect abnormal operation. Even if you did, the guidance is to continue the takeoff and disconnect that autothrottle and set thrust manually.
 
SAAFNAV
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RE: Signif Of The 40- To 100-knot Call During T/O Roll

Sun May 19, 2013 8:23 am

I don't know how many other aircraft doesn't have nose-wheel steering that is commanded by the rudder pedals, but the
C-130's 80 Knot call is where the PF takes control, since up to about 70 Knots the rudder is ineffective and the Captain steers the plane with the tiller and rudder.

So at 80 Kts the captain will take the stick from the-co pilot and continue the take-off, or he will give the rudder pedals and throttles to the co-pilot for his take-off.

Is that similar in other aircraft?

Erich
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bueb0g
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RE: Signif Of The 40- To 100-knot Call During T/O Roll

Sun May 19, 2013 9:18 am

Quoting BoeingGuy (Reply 2):
80 knots is also when the two pilots are supposed to verify their Airspeed indications are 80, and when the Autothrottle goes into Throttle Hold (on a Boeing airplane). As the other reply indicated, about 80 knots the approved reasons for an RTO get much shorter.

This can also be at 100 knots. Many airlines have a 100 knot call to verify airspeed and signal a change in RTO parameters. This tends to be an Airbus thing, I think.

Quoting saafnav (Reply 5):
So at 80 Kts the captain will take the stick from the-co pilot and continue the take-off, or he will give the rudder pedals and throttles to the co-pilot for his take-off

Not for airliners. Almost all have some kind of nosewheel steering capability from the rudder pedals.
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tb727
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RE: Signif Of The 40- To 100-knot Call During T/O Roll

Sun May 19, 2013 7:44 pm

Quoting BoeingGuy (Reply 4):
What was the difference between the 80 knot call and 100 knots? I'm guessing 80 was for the change in reasons to RTO, and 100 was the airspeed check?

By 80 you also had to release the nose-wheel steering button I think it was and the 100 knot check was meant to be an airspeed crosscheck. It was my first jet and first airline, so looking back at it now some of the stuff we did was a little overkill but they meant well.
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novice
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RE: Signif Of The 40- To 100-knot Call During T/O Roll

Thu May 23, 2013 3:14 pm

Quoting BoeingGuy (Reply 4):
I've heard "Eighty" and I've heard "Eighty Knots, Throttle Hold" on Boeing airplanes. Throttle Hold is no biggie. Even if the Autothrottle Mode didn't change to Hold for some reason, guidance is to leave the autothrottle engaged and continue the takeoff as long as you don't have any other reason to suspect abnormal operation. Even if you did, the guidance is to continue the takeoff and disconnect that autothrottle and set thrust manually.

What is the difference between having the autothrottle mode on hold and having the autothrottle engaged? as stated when its not on autothrottle hold mode the guidance is to continue the T/O and disconnect that autothrottle and set thrust manually.

Quoting saafnav (Reply 5):
I don't know how many other aircraft doesn't have nose-wheel steering that is commanded by the rudder pedals, but the
C-130's 80 Knot call is where the PF takes control, since up to about 70 Knots the rudder is ineffective and the Captain steers the plane with the tiller and rudder.

So at 80 Kts the captain will take the stick from the-co pilot and continue the take-off, or he will give the rudder pedals and throttles to the co-pilot for his take-off.

Is that similar in other aircraft?

"Since up to about 70 knots the rudder is ineffective and the Captain steers the plan with the tiller and rudder" That sentence doesn't make sense to me seems to be a contradiction also what is a tiller?

Why would the co-pilot have the stick in the first place if its ineffective, would it not make more sense for the captain to have control of the stick since he already has control of the rudder pedals and throttles?
 
SAAFNAV
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RE: Signif Of The 40- To 100-knot Call During T/O Roll

Thu May 23, 2013 4:34 pm

Quoting novice (Reply 8):
Why would the co-pilot have the stick in the first place if its ineffective, would it not make more sense for the captain to have control of the stick since he already has control of the rudder pedals and throttles?

The captain has got one hand on the tiller and the other on the throttles. The co-pilot has to keep the elevator neutral and wings level.
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BoeingGuy
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RE: Signif Of The 40- To 100-knot Call During T/O Roll

Thu May 23, 2013 5:10 pm

Quoting novice (Reply 8):
What is the difference between having the autothrottle mode on hold and having the autothrottle engaged? as stated when its not on autothrottle hold mode the guidance is to continue the T/O and disconnect that autothrottle and set thrust manually.

The Autothottle sets the takeoff thrust to the target EPR or N1. At 80 knots it goes into the HOLD mode. It actually completely removes power from the servo motor that drives the throttles. It does this for two reasons:

1) So the autothrottle won't try to put the throttles back to the set point if the Captain has to retard them or push them forward during an emergency.

2) So the autothrottle would be incapable of erroneously moving the throttles during a critical point of takeoff if it malfunctioned.

The Autothrottle Servo motor will be repowered and go back into the applicable mode, the next time something happens (VNAV engages; Climb Thrust is selected; another pitch mode is selected, etc depending on model and what modes the crew selects).
 
CosmicCruiser
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RE: Signif Of The 40- To 100-knot Call During T/O Roll

Thu May 23, 2013 9:55 pm

Quoting saafnav (Reply 9):
The captain has got one hand on the tiller and the other on the throttles. The co-pilot has to keep the elevator neutral and wings level.

once we were lined up on the runway the capt never used the tiller again.
 
SAAFNAV
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RE: Signif Of The 40- To 100-knot Call During T/O Roll

Fri May 24, 2013 2:26 am

Quoting CosmicCruiser (Reply 11):

once we were lined up on the runway the capt never used the tiller again.

In what aircraft? As I said above, the C-130 doesn't have a linkage between rudder pedals and nose wheel steering.
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CosmicCruiser
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RE: Signif Of The 40- To 100-knot Call During T/O Roll

Fri May 24, 2013 2:33 am

Quoting saafnav (Reply 12):
the C-130 doesn't have a linkage between rudder pedals and nose wheel steering.

That would make sense then. I was referring to the jets I flew.

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