FEAST Dynamic Radar Conflict Management 3 — Questions and Answers
Question 1: In radar conflict management, the 'point of no return' (PNR) refers to:
- The latest time at which a conflict resolution instruction can be issued and still restore safe separation (Correct answer)
- The point where two aircraft are so close that separation is no longer possible
- The moment TCAS issues resolution advisories to both aircraft
- The speed-distance point where no heading change can avoid the conflict
Correct answer: The latest time at which a conflict resolution instruction can be issued and still restore safe separation
The PNR is the last moment at which controller action can restore separation; after this point the situation can only be managed, not resolved by normal means.
The point of no return in ATC conflict management defines the temporal boundary beyond which a standard separation instruction (heading change or level change) cannot be executed fast enough to prevent the separation minimum being infringed. Beyond PNR, TCAS is the remaining line of defence. Controllers must detect and resolve conflicts well before the PNR to maintain safe operations. FEAST scenarios are timed to test whether candidates detect and act on conflicts before the PNR, not just when the threat becomes visually obvious.
Question 2: Aircraft Charlie is descending through FL250 at 2,000 ft/min. Aircraft Delta is climbing through FL230 at 1,500 ft/min. They are on the same track. The current vertical separation is 2,000 ft. Approximately how many minutes before they close to 1,000 ft?
- Approximately 0.29 minutes (about 17 seconds) — combined closure rate is 3,500 ft/min (Correct answer)
- Approximately 2 minutes — only the faster aircraft's rate matters
- Approximately 1 minute — the combined rate is 2,000 ft/min
- Approximately 3 minutes — closure rate of 500 ft/min because they are both on same track
Correct answer: Approximately 0.29 minutes (about 17 seconds) — combined closure rate is 3,500 ft/min
Combined vertical closure rate = 2,000 + 1,500 = 3,500 ft/min. Distance to close from 2,000 ft to 1,000 ft = 1,000 ft. Time = 1,000 ÷ 3,500 ≈ 0.29 min ≈ 17 seconds.
When two aircraft are flying toward each other vertically (one descending, one climbing), their vertical closure rate is the sum of both rates: 2,000 + 1,500 = 3,500 ft/min. They currently have 2,000 ft separation and the standard is 1,000 ft. Time to reach 1,000 ft = (2,000 - 1,000) ÷ 3,500 = 0.286 min ≈ 17 seconds. This illustrates how rapidly vertical conflicts can develop during simultaneous climb/descent, requiring immediate controller action the moment the conflict is detected.
Question 3: When using a heading change to resolve a conflict, the controller should aim to turn the aircraft to achieve separation by:
- Turning it away from the conflicting aircraft to increase track divergence and ensure separation on current tracks (Correct answer)
- Turning it toward the conflicting aircraft so they pass each other more quickly
- Issuing an incremental 10-degree heading change and monitoring the effect
- Turning it 90 degrees to stop it moving toward the conflict area
Correct answer: Turning it away from the conflicting aircraft to increase track divergence and ensure separation on current tracks
Heading changes should turn the aircraft away from the conflict to create track divergence, increasing lateral separation and ensuring the tracks will remain separate.
A heading change resolves a lateral conflict by turning one (or both) aircraft so their tracks diverge. The magnitude of the turn must be sufficient to ensure that the new tracks will not return to a conflicting geometry later. A small 10-degree change may only delay conflict, not resolve it. A 90-degree turn is often excessive. The standard approach is to issue a heading change that provides clear track separation for the conflict geometry identified — typically 30 degrees or more depending on geometry. FEAST tests whether candidates understand the principle of track divergence, not just that a heading change must be issued.
Question 4: A controller receives a TCAS RA notification from a pilot. The controller's correct response is:
- Acknowledge the RA and do not issue any instruction that conflicts with the TCAS advisory (Correct answer)
- Override the TCAS advisory with ATC instructions to maintain separation responsibility
- Ask the pilot to confirm the RA type before acknowledging
- Instruct the pilot to ignore the RA and follow ATC instructions
Correct answer: Acknowledge the RA and do not issue any instruction that conflicts with the TCAS advisory
When a TCAS RA is issued, pilots must follow it. Controllers must acknowledge and must not issue conflicting instructions until the RA is resolved.
ICAO and EUROCONTROL procedures specify that when a TCAS Resolution Advisory is issued, the pilot must follow the RA manoeuvre and inform ATC. The controller's mandatory response is: (1) acknowledge ('Roger, TCAS RA'), (2) do NOT issue any instruction that conflicts with the RA (e.g., do not tell the aircraft to descend if the RA says climb), (3) resume normal instructions only after the pilot reports 'TCAS RA clear'. Controllers cannot override TCAS — it is an independent last-resort safety system designed to operate outside normal ATC procedures.
Question 5: In a head-on conflict scenario, the fastest safe resolution method is usually:
- Turning both aircraft in the same direction by the same number of degrees — each turns right (Correct answer)
- Turning one aircraft right and the other left to maximise divergence speed
- Climbing one aircraft and descending the other simultaneously
- Reducing the speed of both aircraft to reduce closure rate
Correct answer: Turning both aircraft in the same direction by the same number of degrees — each turns right
Standard right-hand turns for both aircraft (in the same rotational direction) ensures each pilot turns away from the other in a predictable way, creating maximum lateral divergence.
The standard resolution for head-on traffic (ICAO and EUROCONTROL) is to turn both aircraft to the right — the same lateral direction. This is intuitive: if both aircraft turn right, each moves away from the other's track. Turning one right and one left would have them turning toward the separation gap, which may reduce divergence. Vertical resolution (one climb, one descend) takes longer because the response time is slower and vertical closure rates can be high. Speed reduction helps but does not resolve the conflict alone at high closure rates. FEAST tests knowledge of standard resolution methods.
Question 6: A controller sees two aircraft converging at the same level with 6 minutes to CPA and currently at 8 NM separation (minimum 5 NM). The situation is:
- Not yet a conflict — separation is above the minimum — but the trend requires monitoring and early action planning (Correct answer)
- An immediate emergency requiring an STCA-level response
- Resolved — 8 NM is sufficient and no further monitoring is needed
- A conflict requiring immediate heading change issuance
Correct answer: Not yet a conflict — separation is above the minimum — but the trend requires monitoring and early action planning
At 8 NM with 5 NM minimum, separation is currently sufficient. However, the converging trend means it will reduce, requiring early planning and preparation for resolution.
At 8 NM, separation exceeds the 5 NM minimum. However, with 6 minutes to CPA and converging tracks, the controller must assess whether the tracks will reduce separation below 5 NM before they pass. If the geometry predicts a minimum below 5 NM, resolution must be initiated before it becomes urgent. This is the concept of 'planned separation' — resolving predicted conflicts while adequate lead time exists, rather than waiting until STCA activates. FEAST tests whether candidates respond to predicted trends, not just current states.
FEAST Dynamic Radar Conflict Management 3
In radar conflict management, the 'point of no return' (PNR) refers to: