KLM MD-11 - Speed Envelope Limiting; Automatic Engagement and Speed Control; LSAS Speed Limiting and Stall Protection

MD-11 Flight Crew Operations Manual
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Automatic Flight -
Description and Operation
Auto.10.24
If descending at Mmo with wing tip tanks less than 90% full, the auto transition
occurs between 30,670 feet and 26,670 feet when computed airspeed exceeds
Vmo-10.
Auto-transition is annunciated on the FMA speed window by a change in the
control target.
Speed Envelope Limiting
The AFS provides full flight regime speed protection using the following:
• ATS self-engagement.
• ATS speed control.
• LSAS speed limiting and stall protection.
• AP/FD automatic pitch mode transitions.
Automatic Engagement and Speed Control
The ATS (if available but not engaged) will auto-engage and transition to a
speed-on-thrust mode when the Vmax or Vmin limit is about to be (or has been)
exceeded. The AP/FD (if engaged) reverts to a compatible pitch mode. ATS
engagement is annunciated by a flashing white A/T OFF on the PFD and HI
SPEED (or LO SPEED) PROTECTION flashing above the FMA speed window
as appropriate.
LSAS Speed Limiting and Stall Protection
If the AP is not engaged and the ATS is not available, or unable to maintain a safe
speed, LSAS speed limiting will engage automatically to provide overspeed or
stall protection. LSAS overspeed limiting is accomplished by changing pitch. The
target speed that LSAS chooses in high speed protection is variable between
Vmo/Mmo, for throttles at idle, and Vmo/Mmo plus 6 knots for throttles at full
power. LSAS will not auto trim in the nose down direction in a high speed
encounter.
LSAS does not provide flap, slat or gear overspeed protection.
LSAS stall protection engages at stickshaker warning angle-of-attack (PLI on the
PFD turns amber). Stickshaker warning is 75 to 85 percent actual stickshaker
angle-of-attack depending on flap setting.
If windshear command guidance is on, LSAS stall protection is delayed until
actual stickshaker angle-of-attack.
After the angle-of-attack is reduced below stickshaker warning, LSAS stall
protection is discontinued and ATS speed control to FMS Vmin is resumed.
October 02, 2006