TCAS

Question 1

What is TCAS II?

Answer 1

TCAS II detects proximity air traffic using the aircraft’s Mode S transponder channel to determine range and altitude with additional dedicated TCAS aerials to establish the traffic’s relative bearing. TCAS II is integrated in the MFD navigation display, to provide situational awareness of proximity and conflicting traffic, and with the PFD attitude display and VSI to give pitch and vertical speed commands for collision avoidance. and gives aural warnings of TA alerts and RA alerts. The system monitors RadAlt, the Air Data Computer (ADC) and aircraft configuration so that dangerous or inappropriate resolution alerts are inhibited.

Question 2

How levels of advisories does the TCAS II present?

Answer 2

2

Traffic Advisory (TA) Indicating range, bearing and relative altitude of intruding aircraft.

Resolution Advisory (RA) which indicates the escape manoeuvre that should be performed to ensure safe vertical separation from intruding aircraft.

Question 3

What is the TCAS II CA logic is based on?

Answer 3

Sensitivity Level - a function os altitude. Sensitivity is greater (i.e. the warning time is greater) at higher altitude

Warning Time - based mainly on the estimated time-to-go (and not distance-to-go) to the Closest Point of Approach (CPA)

Question 4

What is the time on TA?

Answer 4

20-48 Seconds

Question 5

What is the time on RA?

Answer 5

15-35 Seconds

Question 6

What is the objective of a TA?

Answer 6

Objective to aid visual acquisition of an intruder and prepares the crew for a possible RA

Question 7

What is the objective of a RA?

Answer 7

Objective to achieve a safe vertical distance from a threat aircraft (between 300 and 700 ft).

Question 8

What is the Non-Threat Traffic?

Answer 8

Intruder is beyond 5 nm and greater than 1200 ft vertical separation.

Question 9

What is the Proximity Advisory (PA) distance?

Answer 9

Intruder is within 5 nm and less than 1200 ft vertical separation.

Question 10

What is the TCAS Altitude Range - ABOVE?

Answer 10

Displays non-threat and proximity traffic from 9900 ft above the aircraft to 2700 ft below the aircraft; typically used during the climb phase of flight.

Question 11

What is the TCAS Altitude Range - NORMAL?

Answer 11

Displays non-threat and proximity traffic from 2700 ft above the aircraft to 2700 ft below the aircraft; typically used during the en-route phase of flight.

Question 12

What is the TCAS Altitude Range - BELOW?

Answer 12

Displays non-threat and proximity traffic from 2700 ft above the aircraft to 9900 ft below the aircraft; typically used during the descent phase of flight

Question 13

What is the TCAS Altitude Range - UNREST?

Answer 13

(Unrestricted) All traffic is displayed.

Question 14

What are the actions on Climb or Descend RA?

Answer 14

Aural Alert: “CLIMB, CLIMB!” or “DESCEND, DESCEND!”.

Pilot Action: Start climbing or descending to achieve the vertical speed of 1500-2000 ft/min

Question 15

What are the actions on Increase Climb or Increase Descent RA?

Answer 15

Aural Alert: “INCREASE CLIMB, INCREASE CLIMB!” or “INCREASE DESCEND, INCREASE DESCEND!”.

Pilot Action: Increase climb or descent rate to achieve 2500-3000 ft/min

Question 16

What are the actions on Crossing Climb or Crossing Decent RA?

Answer 16

Aural Alert: “CLIMB, CROSSING CLIMB, CLIMB, CROSSING CLIMB!” or “DESCEND, CROSSING DESCEND! DESCEND, CROSSING DESCEND!”.

Pilot Action: Start climbing or descending to achieve the vertical speed of 1500-2000 ft/min. Note that the altitude of the threat aircraft will be crossed during the RA.

Question 17

What are the actions on Level Off RA (Initial RA)?

Answer 17

Aural Alert: “LEVEL OFF! LEVEL OFF!”

Pilot Action: Reduce the vertical rate to 0 ft/min (i.e. level off immediately not at the standard next flight level e.g. FL200, FL210).

Question 18

What are the actions on Level Off RA (Weakening RA)?

Answer 18

Aural Alert: “LEVEL OFF! LEVEL OFF!”. Weakening RA (usually subsequent to Climb or Descend RA).

Pilot Action: Reduce the vertical rate to 0 ft/min (i.e. level off immediately).

New RA introduced in TCAS II 7.1 replacing “Adjust vertical speed, adjust” RA.

Question 19

What are the actions on Reversal Climb or Reversal Descend?

Answer 19

Aural Alert: “CLIMB, CLIMB NOW!” or “DESCEND, DESCEND NOW!”.

Pilot Action: Start climbing or descending to achieve the vertical speed of 1500-2000 ft/min.

Question 20

What are the actions on Monitor Vertical Speed RA?

Answer 20

Aural Alert: “MONITOR VERTICAL SPEED!”.

Pilot Action: No change in vertical speed is required.

Question 21

What are the actions on Maintain Vertical Speed RA?

Answer 21

Aural Alert: “MAINTAIN VERTICAL SPEED!”.

Pilot Action: Continue the current vertical speed (do not reduce).

This RA only occurs when already climbing/descending at more than 1500 ft/min. It may be confusing when climbing but starting to descend (or vice versa) since the display the current vertical speed could already be in the red.

Question 22

What are the actions on Crossing Maintain Vertical Speed RA?

Answer 22

Aural Alert: “CROSSING MAINTAIN VERTICAL SPEED!”.

Pilot Action: Continue the current vertical speed (do not reduce).

The altitude of the threat aircraft will be crossed during the RA. This RA only occurs when already climbing/descending at more than 1500 ft/min.

Question 23

What are the actions on Multi-Threat RA?

Answer 23

Aural Alert: “LEVEL OFF, LEVEL OFF!”.

Pilot Action: Reduce the vertical rate to 0 ft/min (i.e. level off immediately).

A combination of advisories can be issued at the same time to prevent descent and climb toward the intruders below and above. Aural annunciation will vary depending on the manoeuvre required and TCAS version.

Question 24

What are the actions on RA Termination?

Answer 24

Aural Alert: “CLEAR OF CONFLICT!”.

Pilot Action: Return to previous clearance