Direct lift control controls the spoilers and horizontal stabilizers to increase aircraft vertical descent rate during landings. This may be done without changing engine power. Actuating the DLC engage-chaff dispense push-button switch on the control stick grip modifies the pitch and roll computer

Figure 9-38.Wing sweep control system.

 inputs. This modification causes the eight spoiler actuators to position their spoilers 3 degrees up from the 0-degree position. The pitch computer also generates the DLC servo actuator command drive at the time of DLC engagement. This command drive, which is applied to the DLC servo actuator, drives the stabilizers to the 6-degree trailing edge down position from the 0-degree position. In DLC, the pitch computer and the roll computer permit additional spoiler and stabilizer control through the DLC-maneuver, flap-glove vane thumb wheel control on the control stick grip. 

Rotating the thumb wheel fully forward, through modified spoiler and DLC command drives, extends the spoilers to the 12-degree position. The stabilizer is driven to the 8-degree trailing edge down position. Rotating the thumb wheel control fully aft retracts the spoilers to the 4.5-degree position and drives the stabilizers to 0 degrees. This maintains aircraft attitude while changing the vertical descent rate. Direct lift control can be disengaged by momentarily pressing the DLC engage-chaff dispense push-button switch or by setting either throttle lever to power.