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Aerocivil Colombia air traffic controller CTA foundations study materials
Aerocivil Colombia air traffic controller CTA foundations study resources

Aerocivil Colombia air traffic controller CTA foundations practice questions

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Question 1Surveillance mechanisms and source limitations

In ATS surveillance, what is the essential difference between primary surveillance radar (PSR) and secondary surveillance radar (SSR)?

  1. PSR requires a transponder reply; SSR paints the aircraft skin with no transponder
  2. PSR detects reflected energy from the aircraft; SSR interrogates a transponder for coded replies Correct answer.
  3. Both systems only display aircraft that have filed an IFR flight plan
  4. SSR cannot display any altitude information

Explanation

Primary radar measures reflected radio energy from the aircraft's surface and does not need a transponder. Secondary radar interrogates an onboard transponder, which replies with identity (Mode A) and, when Mode C or Mode S altitude reporting is available, pressure-altitude information. RAC 65.210(b) tests principles, use, and limitations of ATC equipment.

Question 2Surveillance mechanisms and source limitations

What do SSR Mode A and Mode C provide to the controller?

  1. Mode A provides pressure altitude; Mode C provides the four-digit identity code
  2. Both modes provide only heading and groundspeed
  3. Mode A provides the four-digit identity (squawk) code; Mode C provides pressure-altitude reporting Correct answer.
  4. Mode A provides CPDLC messages; Mode C provides voice

Explanation

Mode A replies carry the four-digit identity code assigned by ATS. Mode C replies carry pressure altitude referenced to 1013.2 hPa, which the display converts to a flight level or altitude as configured. Heading and groundspeed come from track processing or ADS-B/MLAT, not from raw Mode A/C.

Question 3Surveillance mechanisms and source limitations

Why can a primary-radar-only display fail to identify an aircraft that SSR would label?

  1. PSR always includes the flight-plan call sign in the raw return
  2. PSR returns contain no automatic identity or Mode A code; identification must be achieved by other means Correct answer.
  3. PSR works only above FL290
  4. PSR cannot detect aircraft over land

Explanation

A primary-radar skin paint gives range and azimuth (and sometimes height with 3D PSR) but no transponder identity. Without SSR/ADS-B, the controller must identify the target by procedures such as position reports, turns, or correlation with a known departure. This identity limitation is a core RAC 65.210(b) equipment point.

Question 4Surveillance mechanisms and source limitations

Which limitation is characteristic of SSR compared with primary radar?

  1. SSR cannot provide any identity information
  2. SSR is immune to garble, fruit, and reflections
  3. SSR depends on a functioning transponder; a non-replying aircraft may be invisible on SSR-only Correct answer.
  4. SSR always measures geometric height independently of the altimeter

Explanation

SSR sees only aircraft that reply to interrogation. A failed, switched-off, or out-of-coverage transponder yields no SSR target, which is why PSR or procedural backup remains operationally important. SSR is also subject to garble, fruit, and reflections; Mode C altitude is pressure altitude, not independent geometric height.

Question 5Surveillance mechanisms and source limitations

How does precipitation typically affect a primary-radar display used in ATS?

  1. Rain always improves PSR detection of aircraft
  2. PSR is designed so weather is never displayed
  3. Weather returns can clutter the display and mask aircraft skin paints Correct answer.
  4. Precipitation converts PSR into an SSR picture

Explanation

Primary radar energy reflects from rain, hail, and other hydrometeors as well as from aircraft. Intense weather clutter can hide or confuse aircraft returns unless MTI/weather-channel processing and controller technique are applied. SSR replies are much less affected by rain clutter, which is one reason the two sensors are complementary.

Question 6Surveillance mechanisms and source limitations

On an ILS used as an ATC and pilot aid, what do the localizer and glide path provide?

  1. Localizer provides vertical guidance; glide path provides lateral guidance
  2. Localizer provides lateral (course) guidance; glide path provides vertical guidance Correct answer.
  3. Both provide only DME distance
  4. Both provide only aerodrome lighting intensity

Explanation

The ILS localizer defines the extended runway centreline in azimuth. The glide path defines the descent profile, commonly about 3 degrees. DME, if paired, is a separate distance function. Controllers use ILS status and protection (critical/sensitive areas) as equipment-limitation knowledge under RAC 65.210(b) and (f).

Question 7Surveillance mechanisms and source limitations

Compared with classical SSR, what is a defining feature of ADS-B as an ATS surveillance source?

  1. ADS-B requires a ground interrogator identical to Mode A SSR
  2. ADS-B works only if primary radar also paints the target
  3. The aircraft automatically broadcasts position and other data derived mainly from GNSS, without being interrogated like SSR Correct answer.
  4. ADS-B cannot include identity or altitude in the broadcast

Explanation

ADS-B (Automatic Dependent Surveillance–Broadcast) is dependent on the aircraft's navigation source (typically GNSS) and broadcasts position, identity, and other parameters spontaneously. Unlike SSR, it does not need a rotating interrogator. Integrity still depends on GNSS/avionics quality and ground-station coverage-limitations a CTA student must know under RAC 65.210(b) and (f).

Question 8Surveillance mechanisms and source limitations

VHF air-ground communications used in ATC are essentially line-of-sight. What operational limitation follows?

  1. Range is independent of aircraft altitude
  2. VHF always covers an entire FIR from one transmitter
  3. Low-altitude or distant aircraft may be out of radio range even when a high-level aircraft on the same frequency is readable Correct answer.
  4. Terrain never blocks VHF

Explanation

VHF (and UHF) radio energy travels roughly line-of-sight. Radio horizon increases with antenna height, so a low-level aircraft behind terrain or far from the transmitter can be unreadable while a high-level aircraft is solid. ATC frequency and transmitter siting, plus relay procedures, exist because of this RAC 65.210(b) limitation.

Question 9Surveillance mechanisms and source limitations

What additional ATS capability does Mode S offer compared with basic Mode A/C SSR?

  1. Mode S only repeats Mode A and cannot address individual aircraft
  2. Mode S replaces all VHF voice communications
  3. Selective interrogation of individual aircraft and downlink of additional aircraft-derived data (including 24-bit address/call-sign correlation) Correct answer.
  4. Mode S works only for VFR flights

Explanation

Mode S (select) uses a unique 24-bit aircraft address so the ground interrogator can address one aircraft, reducing garble and enabling downlink of extra parameters (e.g. aircraft identification). It does not replace voice or CPDLC and is not VFR-only. These principles and limitations fall under RAC 65.210(b) and, for surveillance ratings, RAC 65.235.

Question 10Surveillance mechanisms and source limitations

Using the ATS training approximation that VHF/radar line-of-sight range in nautical miles is about 1.23 × (√h1 + √h2) with heights in feet, what is the approximate radio-horizon range between a 5,000 ft aircraft and a ground antenna 100 ft above local terrain?

  1. About 25 NM
  2. About 250 NM
  3. About 99 NM Correct answer.
  4. About 500 NM

Explanation

√5000 ≈ 70.7 and √100 = 10, so √h1 + √h2 ≈ 80.7. 1.23 × 80.7 ≈ 99 NM. This is an ICAO/ATS training geometric approximation, not a published RAC 211 Colombian coverage figure; real coverage is reduced by terrain, antenna patterns, and equipment. The calculation shows why low-level aircraft drop off long before FIR-wide VHF is assumed.

Question 11Surveillance mechanisms and source limitations

Multilateration (MLAT) used as an ATS surveillance sensor locates an aircraft primarily by:

  1. Measuring the time difference of arrival of transponder replies at several synchronized ground receivers Correct answer.
  2. Painting the airframe with a primary-radar rotating beam only
  3. Reading the aircraft's paper flight-progress strip
  4. Using HF direction-finding on the distress frequency only

Explanation

MLAT (and wide-area MLAT) computes position from time-difference-of-arrival of SSR/Mode S replies at multiple receivers. It still depends on a transmitting transponder and on geometry/synchronization quality. It is neither PSR nor a strip-marking substitute. Treat coverage and accuracy as equipment limitations under RAC 65.210(b); do not assume unpublished Colombian MLAT separation minima.

Question 12ATS concepts, coordination and aircraft constraints

From an ATS perspective, when does a wing stall and why does that matter to a controller?

  1. A stall occurs only when indicated airspeed is above VMO
  2. A stall occurs when the wing exceeds its critical angle of attack, which can happen at any speed if AOA is too high Correct answer.
  3. A stall is impossible in a climb
  4. A stall occurs only in cloud

Explanation

Lift stalls when angle of attack exceeds the critical AOA, independent of a single 'stall speed' in every configuration. Low speed, heavy weight, icing, or abrupt pitch-up all raise the risk. Controllers affect this through speed control, altitude assignments, and go-around timing (RAC 65.210(c) performance as it affects ATC).

Question 13ATS concepts, coordination and aircraft constraints

Which statement correctly describes the four fundamental forces in steady, unaccelerated, straight-and-level flight?

  1. Lift equals weight and thrust equals drag Correct answer.
  2. Lift equals drag and thrust equals weight
  3. Only thrust and lift act on the aircraft
  4. Weight is always twice lift in cruise

Explanation

In steady level cruise, lift balances weight and thrust balances drag. That equilibrium underpins why reducing thrust causes descent unless attitude is changed, which matters when ATC issues speed or altitude instructions (RAC 65.210(c)).

Question 14ATS concepts, coordination and aircraft constraints

In ICAO Doc 4444 wake-turbulence categories used in ATS training, which statement is correct?

  1. Light aircraft generate the strongest wake vortices
  2. Wake turbulence exists only on the ground
  3. A Heavy-category jet typically generates a more persistent, stronger wake than a Light aircraft, so a Light following a Heavy needs greater wake protection Correct answer.
  4. Wake category depends only on the number of engines

Explanation

ICAO PANS-ATM (Doc 4444) wake categories (Light, Medium, Heavy, and Super) are based primarily on maximum certificated take-off mass. Heavier aircraft generally produce stronger, longer-lived wingtip vortices, so a Light aircraft behind a Heavy is a classic high-risk pairing. Engine count is not the classifier. These are ICAO training concepts; do not treat unpublished Colombian radar wake distances as RAC 211 numbers.

Question 15ATS concepts, coordination and aircraft constraints

If indicated airspeed is held constant while an aircraft climbs into less-dense air, what happens to true airspeed (TAS)?

  1. TAS decreases because the pitot system under-reads
  2. TAS always equals indicated airspeed by definition
  3. TAS increases as density decreases Correct answer.
  4. TAS becomes zero above the transition altitude

Explanation

Indicated airspeed reflects dynamic pressure. In thinner air the aircraft must move faster through the air mass to produce the same dynamic pressure, so TAS rises with altitude/density altitude if IAS is constant. A common ATS approximation is about 2% TAS increase per 1,000 ft. Higher TAS means higher groundspeed in still air, which affects time-to-touchdown and miles-in-trail planning.

Question 16ATS concepts, coordination and aircraft constraints

How does high density altitude affect aircraft performance in a way that changes ATC planning?

  1. Take-off roll shortens and climb gradient increases
  2. Take-off roll lengthens, climb rate and gradient decrease, and TAS for a given IAS is higher Correct answer.
  3. Engines produce more thrust because the air is thinner
  4. Density altitude has no effect below 10,000 ft

Explanation

High density altitude (hot, high, low pressure, or humid) reduces engine/propeller/wing performance: longer take-off distance, poorer climb, higher TAS for a given IAS. At high Andean aerodromes this means more runway occupancy, shallower departure paths, and greater sensitivity to weight and wind. That is exactly the RAC 65.210(c) 'performance as it affects ATC' objective.

Question 17ATS concepts, coordination and aircraft constraints

Where are wake vortices from a Heavy jet typically strongest and most persistent for a following aircraft?

  1. Well above the generating aircraft's flight path in a strong updraft only
  2. Only inside the jet engine exhaust cone within 10 m
  3. Behind and slightly below the generating aircraft, especially in light-wind conditions after take-off or on final Correct answer.
  4. Only over water

Explanation

Wingtip vortices trail behind and sink slowly below the generating aircraft. They are most hazardous to a lighter follower on the same or a lower path, in calm or light wind, after rotation and on short final. Crosswind can drift vortices onto a parallel runway. ICAO PANS-ATM wake procedures exist because of this geometry.

Question 18ATS concepts, coordination and aircraft constraints

Why does a typical jet transport have a reduced climb gradient at high flight levels compared with the same aircraft at medium levels?

  1. Jet engines produce more thrust as air density falls, so climb always improves
  2. Thrust available falls with density while induced drag and the need to exchange energy remain, so excess thrust and climb rate decrease toward the aerodynamic ceiling Correct answer.
  3. Flaps are always fully extended in cruise, destroying climb
  4. ATC vertical separation of 1,000 ft physically prevents climb

Explanation

Excess thrust (thrust minus drag) drives climb. At high altitude, thrust available declines with density and true airspeed is high, so excess thrust shrinks and rate of climb falls toward zero at the ceiling. Controllers must not assume a jet can accept an unrestricted high-rate climb to a distant flight level; step climbs and performance-limited altitudes are normal (RAC 65.210(c)).

Question 19ATS concepts, coordination and aircraft constraints

A twin-turboprop reports an engine failure after departure. What performance effect should the aerodrome controller expect?

  1. Climb gradient and acceleration will usually be reduced, and the crew may need runway heading or a simplified departure, not a tight visual turn Correct answer.
  2. The remaining engine always doubles climb performance
  3. The aircraft must immediately reverse back onto the runway
  4. Wake category automatically changes from Medium to Super

Explanation

One-engine-inoperative climb is certified at a reduced gradient. The crew will protect airspeed, may dump or return overweight, and will typically want a simple, wide trajectory. ATC should not impose tight visual manoeuvres or expect normal second-segment climb. Wake category is based on certificated mass, not engine count.

Question 20ATS concepts, coordination and aircraft constraints

An aircraft is making 240 kt groundspeed. How far will it travel in 12 minutes, and how long would 30 NM take at 180 kt groundspeed?

  1. 36 NM in 12 min; 8 min for 30 NM
  2. 24 NM in 12 min; 15 min for 30 NM
  3. 48 NM in 12 min; 10 min for 30 NM Correct answer.
  4. 60 NM in 12 min; 6 min for 30 NM

Explanation

Distance = speed × time. 240 kt × 12/60 h = 48 NM. Time = distance/speed: 30 NM / 180 kt = 1/6 h = 10 minutes. These time/distance conversions are core ATC planning arithmetic (RAC 65.210(c) and (g)).

Question 21ATS concepts, coordination and aircraft constraints

An aerodrome elevation is 8,000 ft. QNH is 1013 hPa so pressure altitude ≈ 8,000 ft. OAT is 25°C. ISA temperature at 8,000 ft is about −1°C. Using the ATS approximation density altitude ≈ pressure altitude + 120 × ISA deviation (°C), what is density altitude, and how does the warm air affect true altitude versus indicated?

  1. About 4,880 ft DA; true altitude is lower than indicated because the air is warm
  2. About 8,000 ft DA with no temperature effect on true altitude
  3. About 11,120 ft DA; in warmer-than-ISA air the true altitude is higher than indicated for a given altimeter reading Correct answer.
  4. About 20,000 ft DA; true altitude equals flight level always

Explanation

ISA deviation = 25 − (−1) = +26°C. DA ≈ 8,000 + 120 × 26 = 8,000 + 3,120 = 11,120 ft. High DA degrades take-off and climb. Separately, when temperature is above ISA the true altitude is higher than indicated (air column expanded). When temperature is below ISA, true altitude is lower than indicated-'from high to low / from hot to cold, look out below' applies to the cold case. These are ICAO altimetry training relationships (RAC 65.210(e)).

Question 22ATS concepts, coordination and aircraft constraints

Under ICAO SSR code allocation used in ATS training, which Mode A code indicates a general emergency?

  1. 7500
  2. 7600
  3. 7700 Correct answer.
  4. 2000

Explanation

ICAO: 7700 emergency, 7600 radio failure, 7500 unlawful interference. 2000 is a common unassigned/conspicuity code in some regions, not the emergency code. These PANS-ATM/Annex 10 identities are core RAC 65.210(g) radiotelephony and emergency knowledge. Do not treat them as unpublished RAC 211 radar-spacing numbers.

Question 23ATS concepts, coordination and aircraft constraints

Which ICAO Mode A code indicates radio communication failure?

  1. 7500
  2. 7600 Correct answer.
  3. 7700
  4. 0000

Explanation

7600 is the ICAO communications-failure squawk. The pilot will also follow lost-comm procedures (route/level/time). 7500 is unlawful interference; 7700 is emergency. Controllers should still attempt contact on other frequencies and watch for the 7600 ident (RAC 65.210(g)).

Question 24ATS concepts, coordination and aircraft constraints

Which ICAO Mode A code indicates unlawful interference?

  1. 7500 Correct answer.
  2. 7600
  3. 7700
  4. 1200

Explanation

7500 is the ICAO unlawful-interference (hijack) code. Phraseology and procedures are discreet; do not discuss the code on the frequency if that would alert hijackers. 1200 is a US VFR conspicuity code, not the ICAO hijack code. This is RAC 65.210(g) emergency radiotelephony knowledge.

Question 25ATS concepts, coordination and aircraft constraints

Which items must a pilot typically read back, according to ICAO radiotelephony used in CTA training?

  1. Only the aircraft call sign, never altitudes
  2. The entire ATIS word for word on first contact always
  3. Nothing, if the aircraft is in radar contact
  4. Safety-critical instructions such as runway, heading, level/altitude, SSR code, and clearances to enter runway or controlled airspace, among others specified in PANS-ATM Correct answer.

Explanation

ICAO Doc 4444 requires readback of ATC route clearances, runway in use, level, heading, speed, SSR codes, altimeter settings, and runway-entry/line-up/take-off/land clearances, among listed items. Radar contact does not waive readback. Full ATIS readback is not required; the code is. RAC 65.210(g) covers routine phraseology.

Question 26ATS concepts, coordination and aircraft constraints

In ICAO radiotelephony, what is the difference between MAYDAY and PAN PAN?

  1. MAYDAY is distress (grave and imminent danger, requiring immediate assistance); PAN PAN is urgency (serious but no immediate danger to the aircraft) Correct answer.
  2. They are interchangeable greetings
  3. PAN PAN is only used by ATS units; MAYDAY is only used by vehicles
  4. MAYDAY means radio failure; PAN PAN means hijack

Explanation

Distress (MAYDAY, three times) is threat of serious and/or imminent danger and need of immediate assistance. Urgency (PAN PAN) is a condition concerning the safety of an aircraft or other vehicle, or of a person on board or in sight, but not requiring immediate assistance. SSR 7700 often accompanies MAYDAY. RAC 65.210(g) includes emergency phraseology.

Question 27ATS concepts, coordination and aircraft constraints

What is the operational purpose of a NOTAM for a CTA?

  1. A long-term textbook replacement for the AIP
  2. Time-critical aeronautical information (navaid outages, runway closures, lighting, hazards) that could not be published soon enough in the AIP amendment cycle Correct answer.
  3. A weather forecast identical to a TAF
  4. A medical certificate under RAC 67

Explanation

NOTAMs (RAC 65.210(h); RAC 215 AIS in the Colombian suite) notify temporary or urgent changes: unserviceable ILS, closed taxiways, crane obstacles, etc. Controllers must brief NOTAMs affecting their unit. They do not replace the AIP's durable baseline, and they are not METARs.

Question 28ATS concepts, coordination and aircraft constraints

How does flight information service (FIS) differ from an air traffic control service?

  1. FIS issues binding separation clearances between all IFR aircraft in Class A
  2. FIS is identical to area control
  3. Only military units may provide FIS
  4. FIS provides useful information and advice (weather, aerodrome status, traffic information as applicable) but does not provide ATC separation clearances Correct answer.

Explanation

ICAO Annex 11: ATC service prevents collisions and expedites flow by issuing clearances and applying separation where required. FIS advises and informs. A basic Colombian CTA licence may provide FIS and/or clearance delivery (RAC 65.245) without being an aerodrome/approach/area rated controller.

Question 29ATS concepts, coordination and aircraft constraints

An IFR clearance should, as a minimum ICAO content model used in ATS training, include:

  1. Aircraft identification, clearance limit, route, levels, and any required departure/approach or special instructions Correct answer.
  2. Only the ATIS code
  3. Only the squawk, with no route
  4. The controller's personal name instead of the unit call sign

Explanation

ICAO Doc 4444 clearance content typically includes aircraft identification, clearance limit, route, level(s) of flight, and any necessary instructions (SID, departure, transponder, etc.). ATIS and squawk are additional items, not a substitute for the route/limit/level core. RAC 65.210(g) covers ATC procedures and routine phraseology.

Question 30ATS concepts, coordination and aircraft constraints

In a standard ICAO holding pattern, which turn direction is used unless the procedure specifies otherwise?

  1. Left turns
  2. Straight-in only, never turns
  3. Random turns at pilot discretion
  4. Right turns Correct answer.

Explanation

Unless published as a non-standard (left-turn) hold, ICAO holding uses right turns. Inbound timing is 1 minute at or below FL140 and 1.5 minutes above FL140 unless DME legs are specified. Controllers must issue the published holding instruction, not invent a pattern (RAC 65.210(g)).

Question 31ATS concepts, coordination and aircraft constraints

What is the difference between transfer of communication and transfer of control?

  1. They always occur at the same instant and mean the same thing
  2. Transfer of communication is the frequency change; transfer of control is the moment responsibility for the aircraft passes, which may be a published point, time, or level and can differ from the frequency change Correct answer.
  3. Transfer of control is only used for VFR; transfer of communication only for IFR
  4. Pilots decide both without ATS

Explanation

A pilot can be on the next frequency while still under the transferring unit's control until the agreed transfer-of-control point, or vice versa according to letters of agreement. Coordination (estimate, level, squawk) must be completed before control transfers. This is core RAC 65.210(g) ATC procedure knowledge.

Question 32ATS concepts, coordination and aircraft constraints

A pilot declares an emergency descent from high level. What should ATS do first according to ICAO emergency-descent practice used in training?

  1. Ignore the call until the next strip update
  2. Instruct the aircraft to climb back before any broadcast
  3. Change the squawk to 2000 immediately as the only action
  4. Acknowledge, broadcast essential traffic, keep other aircraft clear of the descent path, and obtain intentions (souls, fuel, assistance) as traffic allows Correct answer.

Explanation

An emergency descent is a MAYDAY-level event. The controller acknowledges, warns other traffic (blind broadcast if needed), and provides separation from the descending aircraft's likely path. Climb instructions would contradict the emergency. Squawk 7700 is expected; 2000 is not the emergency code. RAC 65.210(g) covers non-routine and emergency phraseology.

Question 33ATS concepts, coordination and aircraft constraints

What information is a TMA/terminal chart primarily designed to show a CTA?

  1. Oceanic tracks only
  2. Only parking-stand numbers
  3. RAC 67 medical standards
  4. Terminal airspace structure, SIDs/STARs or TMA routes, holds, and sectorization around one or more aerodromes Correct answer.

Explanation

RAC 65.210(h) lists TMA (área terminal) charts among those a CTA must interpret. They depict the terminal airspace, arrivals, departures, and holds that approach/area controllers use. Stand charts are aerodrome/ground; oceanic tracks are en-route/oceanic.

Question 34ATS concepts, coordination and aircraft constraints

An aerodrome chart used by tower control typically includes which data?

  1. Runways, taxiways, holding points, lighting, and coordinates/elevations needed for ground and local control Correct answer.
  2. Only FIR boundary latitudes
  3. Only en-route VOR frequencies nationwide
  4. The text of RAC 65.065

Explanation

Aerodrome charts (RAC 65.210(h)) show the movement area: runways, taxiways, stop bars, ILS critical areas, and elevations. Tower uses them for taxi routing and runway incursion prevention. FIR and en-route navaid networks belong on en-route charts.

Question 35ATS concepts, coordination and aircraft constraints

Before transferring an IFR aircraft to the next ATS unit, what coordination is required in ICAO ATC procedure training?

  1. No coordination if the aircraft is on a published SID
  2. The transferring unit must pass estimate, level, and any restrictions, and obtain acceptance, in accordance with the letter of agreement, before the aircraft enters the next unit's airspace Correct answer.
  3. Only the pilot files a new flight plan with the next FIR
  4. Coordination is required only after the aircraft has already entered the next sector

Explanation

Silent transfer is allowed only when an LOA explicitly authorizes it (e.g. standard SID/level). Otherwise estimates, assigned levels, and coordination must be completed first. Late coordination is a TEM threat. RAC 65.210(g) covers ATC procedures and aeronautical documents (LOAs/MATS).

Question 36ATS concepts, coordination and aircraft constraints

Under ICAO Doc 4444 wake-turbulence categories, why does a Super (e.g. A380) require more protection for followers than a Heavy?

  1. Super aircraft produce no vortices
  2. The Super category identifies types whose wake is treated as more severe than Heavy, so greater time or distance-based wake spacing is applied to following aircraft in PANS-ATM Correct answer.
  3. Super means the aircraft is a glider
  4. Super aircraft are exempt from all wake rules

Explanation

ICAO added Super for specified types (notably A380) whose wakes exceed the Heavy model. Followers therefore get larger wake time/distance than behind a Heavy. Exact local radar distances remain unit/RAC 211/AIP data and are not invented here; the concept is PANS-ATM for RAC 65.210(c)/(g).

Question 37ATS concepts, coordination and aircraft constraints

A pilot reports 'unable ILS, request vectors for the VOR approach' in IMC. What is the correct ATS phraseology/procedure response in ICAO training terms?

  1. Refuse all further service because the ILS is the only legal approach in IMC
  2. Tell the pilot to descend immediately to MDA in any direction
  3. Assign squawk 7500
  4. Acknowledge, verify the aircraft can fly the VOR procedure, coordinate as needed, and issue radar vectors or a clearance to the VOR approach, including a missed-approach expectation Correct answer.

Explanation

Non-routine radiotelephony (RAC 65.210(g)) includes equipment failures. The controller acknowledges, checks procedure capability, provides an alternative instrument procedure, and protects missed-approach paths. Random descent to MDA is not a clearance. 7500 is hijack, not navaid failure.

Question 38ATS concepts, coordination and aircraft constraints

A NOTAM states the ILS glide path is unserviceable and the approach chart shows the procedure may be flown as localizer-only with higher minima. What should the approach controller do?

  1. Continue to clear aircraft for the ILS with standard CAT I minima as if the GP were working
  2. Brief the NOTAM, clear only for the localizer (or other available) procedure at the published higher minima, and protect the missed-approach segment accordingly Correct answer.
  3. Ignore AIS because radar vectors replace all minima
  4. Close the CTA licence examination for the day

Explanation

RAC 65.210(h) requires NOTAM and approach-chart interpretation together. An unserviceable GP means the precision ILS is not available; the charted localizer-only or alternative procedure and its MDA/DA apply. Radar vectors do not cancel published minima. This is combined AIS/procedure application, not a licensing-admin event.

Question 39Controller attention, communication and teamwork

In ICAO Threat and Error Management (TEM), which statement best defines a threat?

  1. A threat is the controller's intentional violation of a clearance
  2. A threat is an event or error that occurs outside the influence of the operational personnel and that must be managed to maintain safety margins Correct answer.
  3. A threat is only a technical radar failure
  4. A threat is the same as an undesired aircraft state

Explanation

ICAO TEM (used in RAC 65.210(d) human-performance training) defines threats as events or errors that occur beyond the immediate influence of the crew/controller (weather, traffic, airport, equipment, company) and that increase operational complexity. Errors are actions or inactions by the operational personnel. An undesired aircraft/ATC state is the last-stage condition that can lead to an incident if not recovered.

Question 40Controller attention, communication and teamwork

Why is controller fatigue treated as a flight-safety issue in ATS human performance?

  1. Fatigue only affects pilots, never controllers
  2. Fatigue improves visual scan by reducing blink rate
  3. RAC 65 prohibits any discussion of fatigue
  4. Fatigue degrades attention, memory, and decision speed, raising the risk of hearback errors and missed conflicts Correct answer.

Explanation

Fatigue is a well-documented TEM threat: it slows reaction, narrows scan, and increases expectation bias. Shift work and circadian disruption are typical ATS sources. Managing fatigue (rostering, rest, reporting) is part of RAC 65.210(d) human performance, not a topic RAC 65 bans.

Question 41Controller attention, communication and teamwork

What is the purpose of a readback in ATS radiotelephony from a human-performance standpoint?

  1. To fill frequency time so other aircraft wait
  2. To replace radar identification
  3. To satisfy a medical Class 3 hearing test
  4. To confirm that the clearance or instruction was received and understood, catching hearback/readback errors Correct answer.

Explanation

Readback is a TEM defence: the controller hears whether the pilot captured runway, heading, altitude, SSR code, and similar safety-critical items. Failure to listen to the readback (hearback error) is a classic ATC human-factors accident path. ICAO Doc 4444/Doc 9432 phraseology used in CTA training requires readback of specified items.

Question 42Controller attention, communication and teamwork

A controller expects AVIANCA 201 to report leaving FL190 and 'hears' that report when the pilot actually said FL170. What human-factors phenomenon is this?

  1. Expectation bias (hearback/expectation error) Correct answer.
  2. Vestibular spatial disorientation of the controller
  3. A Mode C encoder failure by definition
  4. The cocktail-party effect improving accuracy

Explanation

Expectation bias leads a listener to perceive the message they predicted. In ATS it produces hearback errors: the strip or plan said FL190, so FL170 is misheard. Defences include full readback listening, stripping, and cross-checking Mode C. It is not inner-ear disorientation (a pilot vestibular issue).

Question 43Controller attention, communication and teamwork

Why are the hours around 03:00–05:00 local time often higher-risk for ATS night shifts?

  1. Circadian low: alertness is typically poorest in the early morning biological night Correct answer.
  2. VHF radios legally shut down at 04:00
  3. ICAO forbids night ATS
  4. Density altitude is always maximum at 04:00 regardless of temperature

Explanation

Human circadian rhythm produces a well-known alertness trough in the early morning. Combined with sleep debt, this is a TEM threat on night watch. Radios do not shut down; ICAO does not forbid night ATS; density altitude follows temperature and pressure, which are often lower (better performance) at night, not automatically maximum.

Question 44Controller attention, communication and teamwork

When traffic load spikes, which TEM strategy best matches 'shedding' lower-priority tasks?

  1. Continue non-urgent landline chats while delaying conflict resolution
  2. Protect separation and safety-critical communications first; defer strip tidying, non-urgent coordination, and lengthy explanations Correct answer.
  3. Stop listening to emergency frequencies to reduce noise
  4. Issue no further clearances for 15 minutes regardless of traffic

Explanation

Under high workload, effective TEM prioritizes collision prevention, timely transmissions, and essential coordination. Administrative or low-value tasks are shed or delayed. Ignoring emergencies or imposing an arbitrary service stop creates new threats. Asking for help (supervisor, splitter, planner) is part of the same strategy.

Question 45Controller attention, communication and teamwork

In a two-person tower (local and ground), what is a correct team-resource-management behaviour when local is overloaded?

  1. Ground should stay silent even if they see a runway conflict
  2. Only the supervisor may ever speak about traffic
  3. Crew resource management applies only in aircraft cockpits, never in ATS
  4. Ground may offer a safety backup (pointing out a conflict or taking a frequency) according to unit procedures; silence is not a virtue Correct answer.

Explanation

TRM/CRM in ATS means using all available resources, including the other controller's eyes and a supervisor. A ground controller who sees a landing/crossing conflict must speak up. RAC 65.210(d) includes human performance; team defences are part of TEM, not cockpit-only doctrine.

Question 46Controller attention, communication and teamwork

Which set correctly matches ICAO TEM categories?

  1. Threats, errors, and undesired states (of aircraft or of the ATS operation) Correct answer.
  2. Only 'pilot deviation' and 'ATC deviation' with no threats
  3. Swiss-cheese layers named Prevention, Promotion, and Punishment
  4. SHEL elements renamed as the only TEM terms

Explanation

ICAO TEM uses three linked categories: threats, errors, and undesired states. Managing threats reduces error opportunity; trapping errors prevents undesired states; recovering undesired states prevents incidents. SHEL (Software, Hardware, Environment, Liveware) is a related but distinct human-factors model; do not blend it as if it were TEM's three categories.

Question 47Controller attention, communication and teamwork

A thunderstorm is on final (threat). The controller issues a landing clearance without a wind-shear warning (error). The aircraft goes around below minima in severe shear (undesired state). What is the correct TEM reading?

  1. The thunderstorm was an error because the controller did not cause the weather
  2. The missed warning was a threat because it occurred inside the controller's actions
  3. Weather was a threat, omitting the warning was a controller error, and the unstable low go-around is an undesired aircraft state requiring recovery Correct answer.
  4. TEM does not apply once the aircraft is on final

Explanation

Threats originate outside the controller (the CB). Errors are the controller's acts or omissions (no wind-shear/weather information, inadequate spacing). The resulting energy/path state of the aircraft is an undesired state. TEM still applies on final; that is often when margins are thinnest (RAC 65.210(d)).

Question 48Controller attention, communication and teamwork

After a sudden emergency call, a controller fixates on that aircraft and stops scanning the rest of the sector. Which human-performance issue is this, and what is the TEM defence?

  1. Startle/channelized attention; use a scan pattern, request help, and protect other traffic's separation Correct answer.
  2. Improved situational awareness; ignore other aircraft until the emergency lands
  3. A medical Class 3 vision failure by definition
  4. Expectation bias that the emergency aircraft is still at its last strip level

Explanation

Startle can produce tunnel vision (channelized attention). The emergency aircraft needs service, but other pairs may be closing. Defences are a deliberate scan, splitting the sector, a planner/supervisor, and short, clear phraseology. This is not a medical-class diagnosis and is distinct from expectation bias about a level report.

Question 49Meteorology for ATS

What is the main difference between a METAR and a TAF for ATS use?

  1. A METAR is a routine aerodrome observation; a TAF is a forecast for a specified period at an aerodrome Correct answer.
  2. A METAR is a 30-hour forecast; a TAF is a single wind reading
  3. Both are identical SIGMET products for en-route CBs
  4. TAFs replace NOTAMs for runway closures

Explanation

METAR (and SPECI) report observed weather at an aerodrome. TAF forecasts expected conditions for a validity period. SIGMETs are en-route significant-weather warnings. NOTAMs, not TAFs, announce runway closures. RAC 65.210(e) requires use of meteorological documentation.

Question 50Meteorology for ATS

What does QNH represent when set on a sensitive pressure altimeter?

  1. Atmospheric pressure at the station reduced to mean sea level so the altimeter reads aerodrome elevation on the ground Correct answer.
  2. Pressure at the runway surface so the altimeter reads zero on the ground (that is QFE)
  3. Always 1013.2 hPa regardless of weather (that is QNE/standard setting)
  4. The magnetic heading of the active runway

Explanation

QNH is sea-level pressure derived from station pressure so that on the ground the altimeter shows aerodrome elevation. QFE makes the altimeter read height above the QFE reference (often the runway). Standard setting 1013.2 hPa is used above transition altitude to display flight levels (QNE). RAC 65.210(e) explicitly includes altimetry.