MD-11 Flight Crew Operations Manual
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Automatic Flight -
Description and Operation
Auto.10.22
ATS Clamp Mode
In CLAMP mode the ATS is engaged, but the ATS servos cannot move the
throttles. CLAMP mode is enabled in the following conditions:
• Takeoff mode on the ground and two or more engine thrust commands are
less than 70 percent of the maximum takeoff setting.
• Takeoff mode is engaged and IAS exceeds 80 knots.
• In flight when command input places the throttles in flight idle and further
thrust reduction is required.
• Windshear mode after throttles have reached the maximum rated thrust.
CLAMP mode is annunciated on the FMA.
ATS Unclamp
The ATS will resume normal operation out of the CLAMP mode for the following
conditions:
• Takeoff mode on the ground and two or more engine thrust commands
exceed about 70 percent of the maximum takeoff setting.
• The aircraft is in flight above 400 feet and the takeoff mode is terminated
by selection of any other vertical path control mode by the AP/FD or
FMS.
• A command is generated for increased thrust while the ATS is operating
in the in-flight idle CLAMP mode.
• Exit of windshear mode.
In a similar manner, the engine trim system resumes normal operation when:
• In-flight termination of the takeoff mode occurs.
• The mid-select engine exceeds the N1 threshold.
ATS Thrust Control
The ATS provides automatic thrust limiting for all thrust and speed control modes.
The N1 of each engine is constrained between the maximum limit defined by the
FMS and a flight idle limit.
The N1 is also constrained by the engine full authority digital electronic control
(FADEC).
The ATS thrust limit control modes are:
• Takeoff.
• Go-around.
• Climb.
• Cruise (alternate climb).
• Windshear.
•Idle.
October 02, 2006
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