LOW SPEED PROTECTION AND STALL RECOVERY
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PDF, HUD LOW SPEED WARNINGS AND INDICATIONS
AUTOTHROTTLE SYSTEM PROTECTION
FLIGHT CONTROL SYSTEM PROTECTIONS
LOW SPEED PROTECTION BEHAVIOUR CONDITIONS
FCTM STALL PROTECTIONS DEMOSTRATION
APPROACH TO STALL OR STALL RECOVERY
LOW SPEED WARNINGS AND INDICATIONS
PFD
3- FLAP MANEUVERING SPEEDS
 Indicates flap-maneuvering speed for flap retraction or extension.
 Not displayed above approximately 20,000 feet altitude.
4- LANDING REFERENCE SPEED
 Displays the VREF speed as selected on the CDU. (Refer to Approach
Reference Page in Chapter 11, Section 43, for additional information.)
 VREF speed is displayed at the bottom of the airspeed indication when the value
is off the scale.
5- MINIMUM MANEUVERING SPEED
 Top of amber bar indicates minimum maneuvering speed. This airspeed
provides:
 1.3 g maneuver capability to stick shaker below approximately 20,000 ft
 1.3 g maneuver capability to low speed buffet (or an alternative approved
maneuver capability as preset by maintenance) above approximately 20,000 ft
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Displayed with first flap retraction after takeoff.
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Note: 1.3 g maneuver capability occurs at 40º of bank in level flight. (25º of
bank and 15º overshooting)
6- MINIMUM SPEED
 Indicates the airspeed where stick shaker activates.
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FCOM 10.10.4
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3- PITCH LIMIT INDICATION (PLI)
 Indicates pitch limit (stick shaker activation point for the existing flight
conditions).
 Displayed when the flaps are not up,
 Or at slow speeds, decreases into the amber band with the flaps up.
 The PLI is displayed only on the PFD and is relative to the airplane pitch
reference symbol
6- AIRPLANE SYMBOL
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Indicates airplane attitude with reference to the IRS horizon.
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FCOM 10.10.6
HUD
4- AIRPLANE SYMBOL
 Indicates airplane attitude with reference to the IRS horizon.
 The same as PFD
5-ANGLE OF ATTACK LIMIT
 Referenced to the flight path vector symbol. The distance between the AOA
limit symbol and the flight path vector symbol represents the margin available
to stick shaker.
 Displayed during any of the following:
 Angle-of-attack is within 5º of stick shaker, or
 Whenever stick shaker is active, or
 Whenever windshear (solid) guidance cue is displayed
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FCOM 10.12.5
ANGLE-OF-ATTACK LIMIT SYMBOL
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The airplane's angle-of-attack (AOA) limit is depicted on the HUD by the
angle-of-attack limit symbol.
The distance between the AOA limit symbol and the flight path vector
symbol represents the margin available before stick shaker occurs.
When the AOA limit symbol is positioned on the flight path vector symbol
(boxed ends set on the flight path vector symbol wings), the airplane is at the
stick shaker angle of attack.
The PFD contains a similar symbol called the pitch limit indicator (PLI).
However, on the PFD, the PLI is displayed relative to the airplane reference
symbol, not to the flight path vector.
The AOA limit symbol is displayed during any of the following:
 angle of attack is within 5º of stick shaker, or
 stick shaker is active, or
 windshear alerting with (solid) guidance cue displayed
AUTOTHROTTLE SYSTEM PROTECTION
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The autothrottle can support stall protection if armed and disconnected. (A/T
arm switches on and A/T MCP switch disconnected)
If speed decreases to near stick shaker activation, the autothrottle connects in
SPD mode and advances thrust to maintain minimum maneuvering speed
(approximately the top of the amber band) or the speed set in the mode control
panel speed window, whichever is greater.
The EICAS caution message AIRSPEED LOW is displayed when speed
decreases approximately half way thought the amber band
AUTOMATIC ACTIVATION (FCOM 4.20.10)
WARNING
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The A/T will not automatically activate to support stall protection when
the pitch mode is FLCH SPD or TOGA
The A/T will not automatically activate to support stall protection when
the A/T mode is HOLD
The autothrottle system does not reposition thrust levers while in HOLD
mode
When the pitch flight mode annunciation is FLCH SPD, the autothrottle
can enter the HOLD mode.
 This occurs if the pilot overrides thrust levers; or, in a decent, when
thrust levers retard to IDLE.
 When in HOLD mode, thrust levers servos are inhibited and the
autothrottle does not control thrust or speed.
 Thrust levers can manually advance
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The A/T low speed protection does not automatically engage when:
 Below 400 feet AFE on takeoff or
 Below 100 feet RA on approach
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FCOM 4.20.10
FLIGHT CONTROL SYSTEM PROTECTIONS
Pitch Envelope Protection
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The pitch envelope protection functions include:
 Overspeed protection
 Stall protection
Overspeed Protection
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Overspeed protection reduces the likelihood of inadvertently exceeding VMO
or MMO by providing enhanced crew awareness of the approach to an
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overspeed condition.
Overspeed protection limits the speed to which the airplane can be trimmed.
At VMO/MMO, the trim reference speed is limited by inhibiting trim in the
nose down direction. The pilot must apply continuous forward column pressure,
at twice the normal force, to maintain airspeed above VMO/MMO.
Stall Protection
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Stall protection reduces the likelihood of inadvertently exceeding the stall angle
of attack by providing enhanced crew awareness of the approach to a stall or to
a stalled condition.
Stall protection limits the speed to which the airplane can be trimmed.
At approximately the minimum maneuvering speed, the trim reference speed is
limited by inhibiting trim in the nose up direction.
The pilot must apply continuous aft column pressure, at twice the normal force,
to maintain airspeed below the minimum maneuvering speed.
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LOW SPEED PROTECTION BEHAVIOUR CONDITIONS
There are small variations considering airplane configuration and flight mode. For
example the amber band in the speed tape appear only with flaps up. And A/T
automatic engagement does not work in same circumstances described in previously
CONDITIONS: AUTOMATIC FLIGHT 01
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A/P ON
ALT, ANNUNCIATE ON FMA VERTICAL MODE
A/T ARM SWITCHES ON
A/T ENGAGE SWITCH LIGHT ON
SELECTED SPEED BELOW AMBER BAND
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COMPLETE LEVEL OF PROTECTION
AIRPLANE RESPONDS
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THE AIRPLANE LOWER THE SPEED IN LEVEL FLIGHT
PLI ON THE PDF.
Depending on airplane flaps position and speed
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AOA LIMIT ON HUD
Depending on AOA margin of 5º or Steak shaker
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A/T IN SPD
A/T maintains the airplane to the minimum manoeuvring speed (top of the
amber band) or the speed set in the mode control panel speed window,
whichever is greater.
AIRSPEED LOW CAUTION MESSAGE
AIRSPEED LOW caution message if the speed decreases approximately half
way thought the amber band
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CONDITIONS: AUTOMATIC FLIGHT 02
 A/P ON
 ALT, ANNUNCIATE ON FMA VERTICAL MODE
 A/T ARM SWITCHES ON
 A/T ENGAGE SWITCH LIGHT OFF
 THRUST LEVER AT IDLE
 SELECTED SPEED BELOW AMBER BAND
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LEVEL OF PROTECTION, WITH A/T WAKES UP
AIRPLANE RESPONDS
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THE AIRPLANE LOWER THE SPEED IN LEVEL FLIGT
PLI ON THE PDF
Depending on airplane flaps position and speed
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AOA LIMIT ON HUD
Depending on AOA margin of 5º or Steak shaker
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A/T WAKES UP
If A/T is disconnected and speed near steak sheaker, the A/T wakes up,
automatically engages in the SPD mode and returns the airplane to the
minimum manoeuvring speed (top of the amber band)
AIRSPEED LOW CAUTION MESSAGE
AIRSPEED LOW caution message if the speed decreases approximately half
way thought the amber band,
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CONDITIONS: AUTOMATIC FLIGHT 03
 A/P ON
 ALT, ON FMA VERTICAL MODE
 A/T ARM SWITCHES OFF
 A/T ENGAGE SWITCH LIGHT OFF
 THRUST LEVER AT IDLE
 SELECTED SPEED BELOW AMBER BAND
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NO LEVEL OF PROTECTION
AIRPLANE RESPONDS
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THE AIRPLANE LOWER THE SPEED IN LEVEL FLIGT
PLI ON THE PDF
Depending on airplane flaps position and speed
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AOA LIMIT ON HUD
Depending on AOA margin of 5º or Steak shaker
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NO A/T WAKE UP
AIRSPEED LOW CAUTION MESSAGE
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AIRSPEED LOW caution message if the speed decreases approximately half
way thought the amber band,
AUTOPILOT CAUTION
As the speed approaches the minimum speed, the AUTOPILOT caution
message appears, an amber line is drawn through the selected pitch mode and
the flight director pitch bar is removed.
STICK SHAKER ACTIVATES
At minimum speed on red and black speed band; the stick shaker activates
STALL RECOVERY PROCEDURE
Recover from the approach to stall in accordance with the Approach to Stall or
Stall Recovery maneuver.
Lateral control is maintained with ailerons and spoilers.
Rudder use is not recommended because it causes yaw and the resultant roll is
undesirable.
After recovery, accelerate to flaps up maneuver speed while retracting the flaps
OR THE AUTOPILOT BEGINS TO DESCEND
Shortly after the stick shaker activates, the autopilot begins to descend from
the selected altitude and maintain a descend at a speed that is slightly above
the minimum speed
To recover, (not using the stall recovery procedure) engage the autothrottle with
a higher speed selected or manually advance the thrust levers.
Select a new pitch mode or disengage the autopilot and manually fly the airplane
back to the starting altitude.
CONDITIONS: MANUAL FLIGHT 01
 A/P OFF, (MAINTAINING heading al level flight)
 A/T ARM SWITCHES ON
 A/T ENGAGE SWITCH LIGHT ON
 SELECTED SPEED BELOW AMBER BAND
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MANUAL COMPLETE LEVEL OF PROTECTION
AIRPLANE RESPONDS
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PLI ON THE PDF
Accordingly to airplane flaps position and speed
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AOA LIMIT ON HUD
Accordingly, to AOA margin of 5º or Steak shaker
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NOSE UP TRIM INHIBIT
The airplane can be trimmed until the airspeed is approximately equal to the
minimum maneuver speed. At approximately the minimum maneuvering speed,
the trim reference speed is limited by inhibiting trim in the nose up direction.
After the airspeed decreases into the amber band, the only use of control column
inputs will maintain level flight.
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A/T IN SPD
A/T maintains the airplane to the minimum manoeuvring speed (top of the
amber band) or the speed set in the mode control panel speed window,
whichever is greater.
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AIRSPEED LOW CAUTION MESSAGE
AIRSPEED LOW caution message if the speed decreases approximately half
way thought the amber band,
CONDITIONS: MANUAL FLIGHT 02
 A/P OFF, (MAINTAINING heading al level flight)
 A/T ARM SWITCHES ON
 A/T ENGAGE SWITCH LIGHT OFF
 THRUST LEVER AT IDLE
 SELECTED SPEED BELOW AMBER BAND
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MANUAL LEVEL OF PROTECTION, WITH A/T WAKES UP
AIRPLANE RESPONDS
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PLI ON THE PDF
Accordingly to airplane flaps position and speed
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AOA LIMIT ON HUD
Accordingly to AOA margin of 5º or Steak shaker
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NOSE UP TRIM INHIBIT
The airplane can be trimmed until the airspeed is approximately equal to the
minimum maneuver speed. At approximately the minimum maneuvering speed,
the trim reference speed is limited by inhibiting trim in the nose up direction.
After the airspeed decreases into the amber band, the only use of control column
inputs will maintain level flight.
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A/T WAKES UP
If A/T is disconnected and speed near steak sheaker, the A/T wakes up,
automatically engages in the SPD mode and returns the airplane to the
minimum manoeuvring speed (top of the amber band)
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AIRSPEED LOW CAUTION MESSAGE
AIRSPEED LOW caution message if the speed decreases approximately half
way thought the amber band,
CONDITIONS: MANUAL FLIGHT 03
 A/P OFF, (Maintaining heading al level flight)
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A/T ARM SWITCHES OFF
A/T ENGAGE SWITCH LIGHT OFF
THRUST LEVER AT IDLE
SELECTED SPEED BELOW AMBER BAND
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NO LEVEL OF PROTECTION
AIRPLANE RESPONDS
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PLI ON THE PDF
Accordingly to airplane flaps position and speed
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AOA LIMIT ON HUD
Accordingly, to AOA margin of 5º or Steak shaker
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NOSE UP TRIM INHIBIT
The airplane can be trimmed until the airspeed is approximately equal to the
minimum maneuver speed. At approximately the minimum maneuvering speed,
the trim reference speed is limited by inhibiting trim in the nose up direction.
After the airspeed decreases into the amber band, the only use of control column
inputs will maintain level flight.
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NO A/T WAKE UP
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AIRSPEED LOW CAUTION MESSAGE
AIRSPEED LOW caution message if the speed decreases approximately half
way thought the amber band,
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STICK SHAKER ACTIVATES
At minimum speed, red and black speed band; the stick shaker activates
If the airspeed reduces to slightly less than minimum speed, increased control
column force is required to maintain level flight.
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STALL RECOVERY PROCEDURE
Recover from the approach to stall in accordance with the Approach to Stall or
Stall Recovery maneuver.
Lateral control is maintained with ailerons and spoilers.
Rudder use is not recommended because it causes yaw and the resultant roll is
undesirable.
After recovery, accelerate to flaps up maneuver speed while retracting the flaps
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APPROACH TO STALL OR STALL RECOVERY