Airborne Collision and Avoidance SystemNavigation — Instrumentation — DGCA CPL practice questions

Question 1 of 6

On receipt of a TCAS RA your action is to:

A.Initiate the required manoeuvre immediately

B.Make a note of the details

C.Request a flight clearance deviation from ATC

D.Do nothing until a TA is received

All 6 questions — Airborne Collision and Avoidance System

Navigation — Instrumentation · DGCA CPL. The correct option is marked on each.

Q1. On receipt of a TCAS RA your action is to:
- A.Initiate the required manoeuvre immediately✓
- B.Make a note of the details
- C.Request a flight clearance deviation from ATC
- D.Do nothing until a TA is received
Why: An RA indicates a serious collision threat (35–15 seconds to CPA). The only correct response is immediate execution of the required manoeuvre. See Section 14 .
Q2. Which statement concerning TCAS is correct?
- A.TCAS II provides avoidance instructions in vertical and horizontal planes
- B.TCAS II cannot provide information on non-SSR equipped intruders✓
- C.TCAS II requires Mode S to be fitted to other aircraft
- D.TCAS II provides advice on which way to turn
Why: TCAS II relies on intruder SSR transponders. Aircraft without transponders are invisible. TCAS II only provides vertical avoidance (never horizontal). Mode S is needed for co-ordinated RAs but not required for basic detection (Mode A/C suffice). See Section 4 .
Q3. The difference between TCAS I and TCAS II is:
- A.TCAS II can provide TAs and RAs whilst TCAS I can only provide TAs✓
- B.TCAS II is only for large aircraft >30 passengers
- C.TCAS I requires Mode A only; TCAS II requires Mode C or S
- D.TCAS II only works with EFIS equipped aircraft
Why: TCAS I = TAs only (alerts crew to look for traffic). TCAS II = TAs + RAs (provides vertical manoeuvre advice). See Sections 2 and 3 .
Q4. The aural messages provided by TCAS II are:
- A.Threat, Climb; Threat, Descend
- B.Climb left; Climb right; Descend left; Descend right
- C.Climb; Descend; Increase Climb; Increase Descent✓
- D.Turn Left, Turn Right, Increase Turn, Decrease Turn
Why: TCAS II RA voice commands: "Climb" "Increase Climb" "Descend" "Increase Descent" "Monitor Vertical Speed" "Decrease Climb" "Decrease Descent" — all in the vertical plane only. No lateral (turn) instructions. See Section 3 .
Q5. RAs may be disregarded only when:
- A.RAs may be disregarded only when the pilot visually identifies the traffic, decides no deviation is necessary, and has clearance confirmed by ATC
- B.RAs may be disregarded when they conflict with an ATC instruction
- C.RAs must never be disregarded
- D.RAs may be disregarded only when the pilot visually identifies the traffic and decides no deviation is necessary✓
Why: RAs may be disregarded ONLY when the pilot visually identifies the conflicting traffic AND decides no deviation is necessary. ATC confirmation is NOT required — in fact, if ATC instruction conflicts with RA, the RA takes precedence. See Section 14 . — This is one of the most exam-important rules. (a) is wrong because ATC confirmation is not required. (b) is wrong because ATC instruction that conflicts = follow the RA. (c) is wrong because there is one exception (visual identification).
Q6. TCAS will NOT give any avoidance commands when the aircraft is below:
- A.1000 ft AGL
- B.1450 ft AGL
- C.400 ft AGL✓
- D.200 ft AGL
Why: TCAS gives no instructions at all below 400 ft AGL . Below 1000 ft: no descent RAs. Below 1450 ft: no increase rate of descent commands. The most restrictive is 400 ft — no instructions at all. See Section 6 . — Three altitude limits to memorise: 400 ft (nothing), 1000 ft (no descent), 1450 ft (no increase descent). On approach these prevent TCAS from commanding dangerous go-arounds below decision height.