IDAC Air Traffic Controller (CTA) common mistakes
IDAC Air Traffic Controller (CTA) · Understand the traps and how to avoid them.
Applying the default 300 m (1 000 ft) vertical separation everywhere, including inside Dominican RVSM airspace above FL 290, or conversely applying 1 000 ft below the transition level where metric/feet conversion and non-RVSM traffic matter.
Candidates memorize one number from initial training and never re-anchor it to the airspace class and flight level band. The IDAC environment mixes oceanic-adjacent routes, RVSM bands and non-RVSM state or military traffic, so a single blanket rule feels safe but is wrong at the margins.
What to do instead
Build a one-page separation matrix before the exam: airspace class, flight level band, surveillance type (radar vs procedural), and special-use areas. For each cell write the minimum and the source (ICAO Annex 2/11, Doc 4444, IDAC AIP). Drill ten mixed scenarios where you must state the minimum and justify it in one sentence.
Reading a METAR or TAF and reporting only the headline weather, missing the operational trigger: RVR or prevailing visibility below approach minima, a TEMPO or BECMG group that changes the category during the validity period, or a windshear/TSRA mention buried in the remarks.
Candidates scan for the cloud base and wind and stop. Trend groups and remarks are syntactically dense, and under time pressure the eye skips the group that actually forces a decision, such as a BECMG 1012/1014 that drops visibility to 1 500 m.
What to do instead
Adopt a fixed decode order every time: wind, visibility/RVR, present weather, cloud, temperature/dewpoint, QNH, then trend and remarks. After decoding, write a one-line operational conclusion ('below CAT I minima from 12Z'). Practice on five real aerodrome reports per study session and time yourself.
Giving a conditional or partial clearance ('maintain FL 150, expect lower in five minutes, call ready for descent') and assuming the crew will treat it as a single instruction, instead of issuing separate, unambiguous clearances with readback of safety-critical items.
Candidates imitate conversational real-world phraseology they have heard on live feeds, where shortcuts are used between familiar crews. In an exam scenario the conditional clearance is the trap: it creates ambiguity about which instruction is active and which items require readback.
What to do instead
Learn the readback-required list cold (route, level, heading, speed, frequency, altimeter setting, runway, conditional clearances). In every practice scenario, phrase one instruction per transmission and explicitly request readback of the safety-critical element. Reject any answer option that bundles an instruction with an expectation.
Confusing the roles of the aerodrome/approach controller and the area controller when an emergency is declared, and failing to state who owns the aircraft, who coordinates with SAR, and who informs the supervisor and adjacent units.
Emergency questions are taught as checklists, so candidates recall actions but not ownership. Under exam pressure they list every possible action in random order rather than the sequence that preserves one controlling agency and timely notification.
What to do instead
Memorize a role-and-sequence template: acknowledge and confirm the nature of the emergency, maintain control and separation, assign a discrete code if not already, notify supervisor and adjacent ATS units, alert ARFF/SAR through the agreed channel, then log times and decisions. Practice three scenarios (engine failure, medical, unlawful interference) and state the sequence aloud.
Treating wake turbulence separation as a fixed distance (for example always 5 NM) rather than applying the correct time- or distance-based minima that depend on the leader/follower weight categories and whether the following aircraft is on approach, departure or crossing behind.
The category table has many cells and candidates remember one common case. They also forget that heavy-to-medium and medium-to-light pairs differ, and that runway-occupancy time replaces distance for departures.
What to do instead
Reconstruct the table from first principles: identify leader category, follower category, phase of flight, then select the minimum. Write the departure time intervals and the approach distance intervals on separate flashcards and test yourself in both directions (given pair, state minimum; given minimum, state pair).
Answering altimetry questions using the standard 1 013.25 hPa without distinguishing QNH, QFE and QNE, or forgetting the transition altitude/level rule and the effect of extremely low QNH on terrain clearance and level allocation.
Candidates conflate the three settings because they all appear in the same chapter, and the transition layer rule is easy to state but hard to apply in a scenario where the QNH is 990 hPa and the MSA is close.
What to do instead
Write a three-line definition for each setting and one worked example per setting showing what the altimeter reads. Then do five transition-layer problems: given transition altitude, QNH and assigned level, compute the actual height and decide whether terrain clearance is assured. State the rule in your own words each time.
On surveillance and automation questions, describing what a radar or flight-data system does without naming the failure mode or the controller's fallback, such as loss of radar identification, a corrupted flight plan, or a display freeze.
Candidates study normal operation because that is what the manual emphasizes, and contingency content feels like a separate topic. In the exam, questions are framed as 'what do you do when X fails', and a description of normal function scores nothing.
What to do instead
For each system (primary/secondary radar, Mode S, ADS-B, flight-data processing, voice recording, datalink), write a two-column card: normal function and degraded-mode action, including separation increase, reversion to procedural control, and notification. Practice stating the fallback in one sentence per system.
Mixing up position-reporting requirements and GNSS/radio-navigation limitations, such as assuming GNSS is available everywhere or that a mandatory reporting point can be omitted because ADS-B is on.
Candidates treat navigation as a chart-reading exercise and skip the regulatory layer that says when reports are mandatory. They also assume satellite navigation is unconditional, ignoring RAIM, NOTAM'd outages and the difference between PBN specifications.
What to do instead
Study the reporting rules alongside the chart: which points are compulsory, what must be included in the report, and when reports may be omitted. For GNSS, learn the concepts of RAIM prediction, receiver autonomy and the meaning of the RNP/RNAV specification. Answer five 'is this report required' scenarios.
Describing human factors in generic terms ('maintain situational awareness', 'manage fatigue') instead of naming a specific mechanism and a specific countermeasure tied to an ATC task.
Human factors is often revised last and from summaries, so candidates produce plausible-sounding slogans. Examiners ask for the mechanism (for example, expectation bias causing a controller to hear a readback that was not given) and the countermeasure (readback verification, cross-check).
What to do instead
For each topic (situational awareness, fatigue, workload, teamwork, just culture, SMS), prepare one concrete ATC example and one countermeasure. Practice answering in the form 'mechanism, example, countermeasure'. Avoid any answer that contains only a virtue word.
Answering air-law questions from general aviation knowledge without anchoring to the specific instrument: ICAO Annex number, IDAC regulation, or national law, and without distinguishing standards from recommended practices.
Candidates learn rules by habit and never map them to their source document. Exam questions often ask which annex or which regulation governs a subject, and a correct-sounding rule attached to the wrong instrument is marked wrong.
What to do instead
Build an annex-to-subject map (Annex 2 rules of the air, Annex 11 ATS, Annex 14 aerodromes, Annex 3 meteorology, Annex 10 communications/navigation/surveillance, Annex 13 accident investigation, Annex 19 safety management) and add the corresponding IDAC regulation where you know it. If you are unsure of a national provision, say so rather than guessing, and verify against the IDAC AIP and current regulation before the exam.