Master Warning System, Microburst Windshear System, GPWS and ACAS

Question 1

What has the complexity of modern aircraft systems resulted in with regards to the master warning system?

Answer 1

The installation of numerous warning lights to alert the crew to system failure or malfunction.

Question 2

Where was the common position of warning lights in early aircraft? What was the disadvantage of this?

Answer 2

• Adjacent to the respective system control.
• Cockpit space limitations meant that many system control panels are located out of the direct view of the flight crew e.g. overhead or side panels.

Question 3

As a result of the disadvantage of the early warning lights, what was developed?

Answer 3

Aircraft designers developed centralised warning panels/systems. In addition, aural and tactile alerts are used to catch the crews’ attention.

Question 4

What is the name for the central warning panel/system for Boeing and Airbus respectively?

Answer 4

• Boeing is Warning Electronics System

- Airbus is Flight Warning Computer

Question 5

What is the basic function of the master warning system? What are the different methods of warning?

Answer 5

To alert the crew to an operational problem, or system malfunction, transport aircraft are fitted with warning systems, which use visual, aural and tactile methods of warning.

Question 6

Describe the function of the visual alert with regards to the warning system?

Answer 6

Coloured lights (red, cyan, orange and white), most warnings utilise this method.

Question 7

What are the lights that illuminate whenever a system malfunction is detected by the Master Warning System? Why does it do this?

Answer 7

• Two Master WARNING or CAUTION lights.
• Get the flight crew’s attention and direct them to the Central Warning Panel or EICAS/ECAM to establish what the problem is.

Question 8

Describe the function of the aural alert with regards to the warning system?
Is it normal for two systems to have the same aural alert?

Answer 8

• Alert the operator to the system with an issue, i.e. a fire warning typically has a fire bell sounding and “FIRE FIRE”.
• Normal for no two systems to have the same aural alert.

Question 9

What are the different types of aural warning alerts?

What are the different uses for each aural warning alert?

Answer 9

• SYNTHETIC VOICE. Used to annunciate time-critical warning alert conditions such as TAWS and ACAS warnings and cautions.
• ALARM BELL. Used for fire warnings only.
• SIREN. Used to annunciate cabin altitude, configuration and Overspeed warning alerts.
• WAILER. Used to annunciate autopilot disconnect warning.

Question 10

What are the different types of aural caution alerts?

What are the different uses for each aural caution alert?

Answer 10

• BEEPER. Used for all system alert level caution messages.

- CLACKER. Used to annunciate overspeed warning.

Question 11

Describe the function of the tactile alert with regards to the warning system?

Answer 11

• When the operator feels some movement as in the stall warning where the control column shakes and if the pilot does not correct the stall conditions, the stick can be pushed out of the pilot’s hands by a stick pusher.

Question 12

What will inhibiting an alert do with regards to the warning system?

Answer 12

Inhibiting will stop the light flashing on the warning system and inhibit the AURAL ALERT, however in some cases, such as the tactile alerts, the only way to inhibit them is to correct the unsafe condition.

Question 13

Why is it important to inhibit alerts with regards to the warning system?

Answer 13

Remove the distracting noise or flashing light from a good logical consideration of the issues at hand.

Question 14

What does the Central Warning Panel display regarding the Master Warning System?

Answer 14

Engine and aircraft system status to the pilots.

Question 15

What are the Boeing and Airbus terms respectively for the electronic system functions of an aircraft?

Answer 15

EICAS - Engine Indicating and Crew Alerting System

ECAM - Electronic Centralised Alert Monitoring

Question 16

List the warning lights found in the Central Warning Panel

Answer 16

• Wind shear warning
• Fire
• Pull Up
• Cabin Altitude
• Configuration
• Autopilot disconnect
• Overspeed

Question 17

List the different wind shear warning system inputs

Answer 17

• Pitot source
• Static source
• RADALT
• Vertical gyro
• Angle of attack transducer
• Flap position
• Flight deck system (visual and aural)
• Flight director computer (FDC)
• Attitude director indicator
  Note last three not likely important

Question 18

List the different inputs of GPWS?

Answer 18

• RADALT with a failure signal
• VSI or BAROMETRIC ALTITUDE RATE COMPUTER with failure signal
• GPS
• ASI/MACH
• FLAP POSITION
• UNDERCARRIAGE POSITION
• GLIDEPATH DEVIATIONS

Question 19

What is the purpose of ACAS?

Answer 19

• Provide alert information of conflicting traffic and warning of an impending collision.
• Reduce the incidence of mid-air collisions and near mid-air collisions between aircraft, by monitoring the airspace around an aircraft for other aircraft equipped with a corresponding active transponder and warning flight crew of the presence of other aircraft that present a threat of a mid-air collision.

Question 20

Describe the function and principle of operation of TCAS 1?

Answer 20

• Intended to just enable pilot to visually acquire nearby traffic.
• Detects and displays range and approximate relative bearing.
• If the other (target) aircraft is carrying Mode C or Mode S SSR, it will also display relative altitude.
• The system alerts pilots visually and aurally -TRAFFIC TRAFFIC- if the conflicting traffic comes within 40 seconds of a potential collision, i.e. Traffic Advisory (TA), but it does not recommend any escape maneuver (resolution advisory, RA).

Question 21

What are the required specifications for TCAS 1?

Answer 21

• Requires provision of a Traffic Advisory when an intruder aircraft comes within 30/40 seconds of the host aircraft.

Question 22

What is the minimum detection range of TCAS 1?

Answer 22

8nm.

Question 23

What does TCAS 2 require that TCAS 1 doesn’t?

Answer 23

Requires an aircraft to be fitted with a Mode S transponder.

Question 24

Describe the function of TCAS 2?

Answer 24

Offers avoidance messages as Resolution Advisories (RA’s), CLIMB, INCREASE CLIMB, DESCEND, INCREASE DESCENT.

Question 25

What if your aircraft and the target aircraft both have Mode S datalink transponders with regards to TCAS?

Answer 25

The TCAS 2 computers onboard the two aircraft will co-ordinate their resolution advisories (RA’s) to offer complimentary vertical avoidance manoeuvres to each flight crew.

Question 26

Explain the principle of operation of the typical ACAS? (under ‘Description of ACAS’ in yellow book)

Answer 26

• Each ACAS equipped aircraft interrogate all transponder aircraft within a predetermined range.
• Interrogation and reply occur on the 1030MHz band, where the interrogation and reply cycle can occur multiples times per second.
• ACAS system builds a 3-Dimensional model of other aircraft in the local airspace, incorporating their bearing, altitude and range.
• The extrapolation of current range and altitude difference to anticipated future values allows ACAS to determine if a threat exists.
• ACAS then gives an appropriate indication and alerts to the flight crew.