The MD-80 is equipped with 4 flap sections, 2 on each wing. The two sections on each wing are mechanically interconnected to form an integrated unit. L and R flaps are interconnected by a bus cable that ensures simultaneous extension and retraction of the flaps. 8 hydraulic actuators, 4 on each side, drive the flaps. The L hydraulic system is connected to the outboard flap section actuators and the R hydraulic system to the inboard actuators.

There are 12 slat sections, 6 on each wing, driven by a cable system connected to a central drive drum which in turn is moved by two actuators. The system is designed in such a way that it is almost impossible to get a split slat condition.
Flap handle

Both the flaps and slats are operated by a flap/slat handle located on the right side of the control pedestal. Fixed handle detents are: UP/RET, 0, 11, 15, 28, 40. To get this fixed detents, the "flap takeoff selector indicator" must be set to "STOW" position.

Flaps 11° or 15° is the standard takeoff flaps used but any optimum flaps 0° to 24° may be used. 28° and 40° is used for normal two engine landings and 28° for single engine approaches.

The slats have three positions.
  • RET - handle in UP/RET
  • MID - handle in FLAP 0° or 11°
  • EXT - handle in FLAP 15°, 28° or 40°

Slats will move from MID to EXT at approximately 14° flap. The dial-a-flap selector therefor has a yellow "do not use" band between 13 and 15 degrees. The retraction sequence for the flaps and slats are; first the flaps, then the slats. Slats can not be retracted until the flaps are retracted.

If the flap/slat handle is set in the 0° to 13° flap takeoff range, airspeed 240 KIAS or less, and either of the two stall warning computers detect an approach -to-stall, the slats will extend automatically from the mid to extended position.
Flap selector
Flap 10 is selected on the FLAP T.O SELECTOR
Flap selector
Warnings (both MASTER CAUTION and ANNUNCIATOR) in case the speed brakes are used with flaps extended.
Also an aural Flap/Brake warning.
Flap indicator
The FLAP/SLAT indicator on the system panel.
  • T/O blue light. FLAP/SLAT handle and slats are in takeoff range.
  • DISAG amber light. Left and right wing slats position do not agree with each other and/or with handle position.
  • AUTO blue light. Slats have automatically extended from mid to extend position by stall warning system.
  • LAND green light. FLAP/SLAT handle is set at 28 or 40 and slats are fully extended.
Flap speed
There is no blowback system on the MD80 that will protect the flaps and slats from an overspeed situation. This placard is to remind the pilots of the maximum allowed speeds.

If the flaps are set to 28° or 40°, and the gear is not in down position, there will be a Flap/Gear warning.