TCAS symbols?
On the display:
- Other traffic: hollow diamond
- Proximate: filled diamond
- TA (traffic advisory): amber filled circle
- RA (resolution advisory): red filled square
DGCA Technical General · 39 questions
TCAS: DGCA Technical General Questions and Answers
39 practice questions on TCAS with answers and explanations, plus the key concepts and formulas, from the TrueHeading question bank.
About this topic
Use this page to revise TCAS for the DGCA Technical General paper. Below are the key ideas first, then 12 practice questions with answers and explanations, picked from the 39 questions in the TrueHeading bank for this topic.
In short: On the display:
Open the full set in the student zone to answer every question, track your accuracy and take timed mock tests.
Key concepts: TCAS
3 ideas to know cold.
What does TCAS do?
It warns of conflicting traffic using transponder replies.
- TCAS I: traffic advisories only
- TCAS II: TA and vertical RAs
- Operates on 1030/1090 MHz and needs the other aircraft to have a transponder
- On an RA, follow it, even if it differs from ATC, and tell ATC
What are TA and RA in TCAS II?
TA: traffic advisory, "TRAFFIC, TRAFFIC" (amber circle). RA: resolution advisory, vertical manoeuvre (red square).
- Follow the RA, even if ATC says otherwise
- Inform ATC after
- TCAS interrogates transponders on 1030 MHz
- Other traffic: hollow diamond; proximate: solid diamond
Practice questions: TCAS
Tap “Show answer” after you have tried each one.
Q1TCAS stands for:
- transponder control and alert system
- terrain and collision avoidance system
- traffic alert and collision avoidance system
- traffic and cruise advisory system
Show answer
Answer: C. traffic alert and collision avoidance system
An airborne system independent of ATC.
Q2TCAS II provides:
- traffic advisories (TA) and resolution advisories (RA) in the vertical plane
- no advisories
- horizontal resolution advisories
- only traffic information
Show answer
Answer: A. traffic advisories (TA) and resolution advisories (RA) in the vertical plane
Advisories only in the vertical plane.
Q3A TCAS Traffic Advisory (TA) is displayed as:
- a green circle
- a blue diamond
- a red square with "CLIMB"
- a yellow/amber circle with the aural message "TRAFFIC, TRAFFIC"
Show answer
Answer: D. a yellow/amber circle with the aural message "TRAFFIC, TRAFFIC"
A TA is a cue to look for the traffic.
Q4The aircraft symbol for "other traffic" in TCAS is:
- a red square
- a green triangle
- an amber circle
- an open (hollow) cyan or white diamond
Show answer
Answer: D. an open (hollow) cyan or white diamond
Traffic within 6 NM and ±1 200 ft is a proximate (solid cyan/white diamond).
Q5The pilot must respond to a TCAS RA by:
- ignoring it until ATC advises
- waiting 30 seconds
- calling ATC first
- following the RA immediately, unless this endangers the aircraft
Show answer
Answer: D. following the RA immediately, unless this endangers the aircraft
ICAO requires immediate response and notification to ATC afterwards.
Q6After a TCAS RA manoeuvre when "CLEAR OF CONFLICT" is announced, the pilot should:
- climb to FL 400
- continue to deviate
- switch off the transponder
- return promptly to the ATC clearance and inform ATC
Show answer
Answer: D. return promptly to the ATC clearance and inform ATC
ATC is informed of the deviation.
Q7The RA aural message "MONITOR VERTICAL SPEED" means:
- climb at 1 500 ft/min
- descend immediately
- disengage the autopilot
- keep the vertical speed out of the red area of the VSI
Show answer
Answer: D. keep the vertical speed out of the red area of the VSI
The current vertical speed is acceptable if it avoids the red zone.
Q8The RA message "REVERSE" indicates:
- a stall
- a change of sense from climb to descent (or vice versa)
- a turn
- no change
Show answer
Answer: B. a change of sense from climb to descent (or vice versa)
e.g., "DESCEND, DESCEND NOW".
Q9TCAS cannot detect an aircraft:
- at night
- at the same level
- in cloud
- without an operating transponder
Show answer
Answer: D. without an operating transponder
It relies on transponder replies.
Q10TCAS II version 7.1 is mandated in ICAO regions for:
- aircraft over 5 700 kg or authorised for more than 19 passengers
- all aircraft
- only helicopters
- only military aircraft
Show answer
Answer: A. aircraft over 5 700 kg or authorised for more than 19 passengers
ICAO Annex 6 requires ACAS II for such turbine-engined aeroplanes.
Q11In TCAS, the "TA ONLY" mode is selected:
- for normal cruise
- to disable the transponder
- for taxi only
- when RA would be inappropriate, e.g., with engine failure or close parallel approaches
Show answer
Answer: D. when RA would be inappropriate, e.g., with engine failure or close parallel approaches
RA is inhibited and only TAs are issued.
Q12Mode S transponders differ from Mode A/C in that they:
- respond selectively to individual addresses and exchange data
- reply to all interrogations
- have no code
- transmit only altitude
Show answer
Answer: A. respond selectively to individual addresses and exchange data
Each aircraft has a unique 24-bit address.
More DGCA Technical General topics
Aerodynamics & Performance181 QFlight Controls & Stability38 QAirframe & Structures25 QPowerplant79 QPropellers32 QAircraft Systems116 QPitot Statics35 QBarometric Altimeters61 QRadio Altimeters37 QVertical Speed Indicators (VSI)32 QAirspeed Indicators24 QAirspeeds41 QMach55 QGyroscope52 QAttitude Indicators20 QTurn and Slip50 QINS, IRS and FMS32 QEFIS24 QAutoflight23 QFlight Director21 QEICAS / ECAM24 QEngine Instruments29 QTemperature Indicators34 QFuel Systems35 QCompass54 QWarning & Recording Systems33 Q
Learn Technical General one-on-one with Nikunj
Unlimited personal sessions, weekly subject tests and lifetime access to the student website. First-attempt pass guarantee, or your money back.