30 Questions
What is the primary function of the Altitude Alerting System?
To warn the pilots when the aircraft is approaching or deviating from the selected altitude
What are the typical height bands within which the Altitude Alerting System operates?
300 feet to 900 feet for Boeing aircraft, 250 feet to 750 feet for Airbus aircraft
What visual indication is provided to the pilots when the aircraft is approaching the selected altitude?
A white box is displayed around the selected altitude and current altitude displays on the PFD
What auditory and visual indications are provided to the pilots when the aircraft deviates from the selected altitude?
The master caution lights illuminate, the caution beeper sounds, and the current altitude box changes to amber
At what distance from the selected altitude does the white box around the altitude displays on the PFD disappear?
300 feet
Which of the following is NOT one of the alerts and warnings provided by the Flight Warning System?
Windshear Warning
What is the primary purpose of the stall warning system?
To alert the pilot of an impending stall condition
What type of sensor is used in the simplest form of stall warning system?
Hinged-vane-type sensor
How does the hinged-vane-type sensor detect an impending stall?
It detects changes in the aircraft's airspeed and angle of attack
What is the regulatory margin between the stall and the stall warning?
5 knots or 5% of the CAS, whichever is greater
What type of stall warning system is used in larger aircraft?
Stick-shaker or stick-pusher
What type of warning signals are typically provided by the stall warning system?
Tactile, auditory, and visual
What are the inputs to the stall warning module in fly-bywire systems?
Angle of attack, flap and slat positions, landing gear weight-on position, airspeed
Where are the angle of attack sensors usually located in fly-bywire systems?
On either side of the front fuselage
What triggers the activation of the stall warning system during take-off in fly-bywire systems?
Nosewheel lift-off
How is the airspeed typically derived in fly-bywire systems?
From the ADC
Which component in fly-bywire systems processes signals from various inputs to produce stall warning output signals?
Stall warning module
What is one of the warning signs in a fly-bywire system that indicates a stall?
Cricket sound
According to the information provided, what happens when the aircraft returns to within 300 feet of the selected altitude?
The master caution lights extinguish, the EICAS caution message disappears, and the current altitude box changes to white.
Under what conditions is the altitude alerting system inhibited, according to the information provided?
When the glideslope is captured or when landing flaps are selected with the gear down.
What is the purpose of the overspeed warning system, as described in the text?
To alert the flight crew if the aircraft exceeds its maximum operating speed limits, as calculated by the air data computer.
Which of the following actions does the overspeed warning system NOT take when an overspeed situation occurs, according to the information provided?
Automatically reduce the aircraft's speed to within the Vmo/Mmo limits.
How can the overspeed warning system be tested on the ground before flight, according to the information provided?
By pressing a test switch, which would then sound the siren or horn as appropriate for that aircraft.
According to the information provided, what would happen in case of a system failure of the overspeed warning system?
The pilot would receive no warning if Vmo or Mmo is exceeded.
What is the primary function of an angle of attack (AoA) sensing system?
To detect the onset of stall conditions and activate warning systems
Which of the following statements about the angle of attack (AoA) is correct?
The AoA at which a wing stalls is higher for swept or delta wings compared to straight wings
What is the purpose of the alpha probe in an angle of attack sensing system?
To directly measure the angle between the wing chord and the airflow
Which of the following is NOT a component of a typical stall warning system?
Pitot-static system
What is the primary cause of a wing stall condition?
Separation of the boundary layer from the wing's upper surface
Which of the following statements about the critical angle of attack (AoA) is correct?
It varies based on the wing's airfoil design
Study Notes
Stall Warning System
- The output signals from the system can be applied to: • a stick-shaker motor • an angle of attack indicator • aural warning • synthetic voice warning • red master WARNING light
Angle of Attack (AoA)
- AoA, also known as alpha (a) angle, is the angle between the chord line of the wing and the direction of relative airflow.
- Lift increases as AoA increases up to a critical value, then decreases due to separation of the slow-moving air from the upper surface of the wing.
- The critical AoA is also referred to as the stalling angle, typically between 12° and 18° for straight wings and up to 30° or 40° for swept or delta wings.
Alpha Probes
- Two types of alpha probes in current use are: • conical slotted probe • vane detector
- The conical probe extends through the aircraft skin perpendicular to the flow of air.
Altitude Alerting System (Boeing 767)
- System inhibition: • Altitude alerting is inhibited in flight whenever glideslope is captured or when landing flaps are selected with the gear down.
- At 900 feet from the selected altitude, or on returning to within 300 feet from the selected altitude: • master caution lights extinguish • EICAS caution message disappears • current altitude box changes to white
Overspeed Warning
- Function: • The purpose of the Overspeed warning system is to alert the flight crew if the airspeed exceeds the Vmo/Mmo limits calculated by the air data computer (ADC).
- Operation: • Sounds the siren or horn • Illuminates the red master WARNING lights • Displays the message OVERSPEED on the EICAS upper display in red
Flight Warning System
- Alerts the crew if there are deviations from certain aerodynamic parameters like: • altitude • airspeed • angle of attack
- Provides the following alerts and warnings: • Altitude Alerting System • Overspeed Warning • Stall Warning
Altitude Alerting System
- Function: • Warns the pilots that the aircraft is approaching or deviating from the altitude selected on the Autopilot control panel.
- Operation: • Height bands within which altitude alerting operates are typically: • 300 feet to 900 feet for Boeing aircraft • 250 feet to 750 feet for Airbus aircraft
Stall Warning System
- Function: • The purpose of the stall warning system is to alert the pilot of an impending stall.
- Operation: • The system processes the signals from the various inputs to produce appropriate stall warning output signals. • The system has the following inputs: • angle of attack • flap and slat positions • landing gear weight-on position • airspeed
- The stall warning must continue until the angle of attack is reduced to approximately that at which the stall warning is initiated.
Test your knowledge about the alerts and warnings provided by a Flight Warning System, including Altitude Alerting System, Overspeed Warning, and Stall Warning. Learn about the functions of each alarm and their significance for aircraft safety.
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