Mauritius DCA IR Theory common mistakes
Mauritius DCA IR Theory · Understand the traps and how to avoid them.
Applying the cruising-level semicircular rule from memory of magnetic tracks without first converting the planned true track to magnetic using the current charted variation, so the wrong flight level is selected for the direction of flight.
Candidates learn the odd/even level table in magnetic terms but practise on questions given in true track, and forget the intermediate conversion step under time pressure. Variation values also change between chart editions, so a memorised number is unreliable.
What to do instead
Adopt a fixed written sequence: true track from the chart, apply charted variation (east subtract, west add) to obtain magnetic track, then apply the semicircular table (000-179 degrees magnetic: odd levels; 180-359 degrees magnetic: even levels) and finally check the level against the table of cruising levels for the route and any notified restrictions. Practise ten conversions until the sequence is automatic.
Treating a clearance limit as an implicit approach clearance, or commencing a published holding, procedure turn or approach without an explicit clearance, when answering scenario questions on ATC clearances and readback.
In simulator and line training the sequence of clearances feels continuous, so candidates assume the next step is authorised. Written questions deliberately omit one clearance to test whether the candidate notices the boundary of the authorisation.
What to do instead
For every scenario question, list exactly what has been cleared (route, level, speed, approach type) and what has not. Remember that a clearance limit is not an approach clearance, that a hold must be entered as cleared, and that readback is required for safety-related items. Answer only from the stated clearance, never from what would normally follow.
Confusing the roles of the pitot-static instruments and the gyroscopic instruments when diagnosing a partial or full panel failure, for example attributing an unreliable airspeed indication to the attitude indicator or misidentifying which instruments remain valid after a static blockage.
Candidates memorise instrument names without mapping each to its pressure source or gyro drive. Questions that describe a specific blockage require reasoning from the source, not recall of a list.
What to do instead
Build a two-column table: pressure instruments (airspeed from pitot and static, altimeter from static, vertical speed from static) and gyroscopic instruments (attitude and heading from vacuum, electrical or air-driven gyros; turn coordinator electrically driven). For each failure mode, such as blocked pitot, blocked static or failed suction, write which indications are affected and how they behave, then test yourself by covering the answer column.
Answering alternator or electrical-system questions by assuming a single alternator failure is immediately catastrophic, rather than identifying what is lost, what remains available and what the load-shedding or standby sequence is.
Candidates focus on the failure itself and not on the aircraft's designed redundancy, so they choose the most dramatic option instead of the technically correct one describing remaining capability.
What to do instead
For each aircraft system in the syllabus, learn the source, the backup and the consequence of losing the primary. For electrical systems, know that a failed alternator leaves the battery supplying essential loads for a limited time, that non-essential loads are shed, and that standby instruments and radios may be on separate buses. Answer by elimination: which option correctly describes what still works.
Computing a take-off, landing or climb performance figure using the pressure altitude and temperature given in the question without correcting for the actual aerodrome pressure, or mixing units between the chart and the given data.
Performance charts are entered with pressure altitude, but questions often supply QNH and elevation, requiring a conversion first. Unit mixing (feet versus metres, kilograms versus pounds, degrees Celsius versus Fahrenheit) is common in distractors.
What to do instead
Before touching the chart, write down the four inputs in the chart's own units: pressure altitude (from elevation and QNH), temperature, weight and configuration. Convert everything explicitly and note the conversion factor used. Then read the chart twice, once for the value and once to verify the entry row and column. Reject any answer that matches an unconverted input.
Planning fuel or alternate requirements by quoting a single regulatory figure without checking whether it applies to the flight category, the weather at destination, or whether an isolated-aerodrome rule applies.
Candidates memorise one numerical rule and apply it universally, whereas the fuel and alternate rules depend on conditions such as whether an approach is available, forecast weather, and the type of operation.
What to do instead
Learn the rules as conditional statements: if the destination forecast is below the specified minima or no approach is available, then an alternate is required; if the destination is isolated, additional fuel is required. For each practice question, state the condition first, then select the rule, then compute. Keep a one-page decision tree of the conditions rather than a list of numbers.
Ignoring the effects of hypoxia, fatigue, carbon monoxide or spatial disorientation when the question describes a subtle scenario, and choosing the answer that describes the aircraft problem rather than the human one.
Candidates study human performance as isolated facts and fail to apply them to scenarios. Early hypoxia and fatigue produce euphoria and degraded judgement, so the pilot in the scenario does not recognise the problem, and the candidate follows the same trap.
What to do instead
Learn the early signs of each condition and, critically, that the affected pilot's own judgement is impaired. In scenario questions, ask what the pilot would fail to notice. For hypoxia, know the time of useful consciousness falls with altitude and that supplemental oxygen and descent are the response; for carbon monoxide, know the insidious onset and the value of fresh air and ground inspection.
Reading a meteorological report or forecast and missing a trend or validity detail, for example treating a TEMPO group as a prevailing condition, misreading a BECMG change group, or ignoring the issue time and validity period.
Candidates decode the first few groups and stop, and the trend groups appear later in the message. The distinction between temporary fluctuations and a permanent change is exactly what the question is testing.
What to do instead
Decode every message in a fixed order: type, issue time, validity, wind, visibility, weather, cloud, temperature, pressure, then all trend groups. For each trend, state whether it is temporary (TEMPO) or becoming (BECMG) and over what period. Practise by writing the decoded message in plain language before looking at the options.
Interpreting an instrument approach chart or RNAV procedure by reading the final approach course and minima but overlooking the missed approach instructions, the transition level, or the required navigation performance and sensor requirements.
The final approach segment is the most familiar part of the chart, so attention concentrates there. Questions on RNAV approaches specifically test whether the candidate knows the performance and equipment requirements, which are stated elsewhere on the chart.
What to do instead
Brief every chart in a fixed sequence: identification and validity, communications and frequencies, transition level, arrival and initial approach, final approach course and descent, minima by category, missed approach, and any notes on equipment or navigation specification. For RNAV procedures, state the navigation specification required and whether a ground-based or space-based sensor is needed before answering.
Describing the missed approach as a single action rather than a sequence, and omitting the decision to go around, the initial climb, the turning or tracking segment and the subsequent holding or diversion.
Candidates rehearse the approach and treat the missed approach as an emergency afterthought. Questions that ask for the correct sequence expose gaps in the order of actions and in the transition to the published missed approach procedure.
What to do instead
Write the missed approach as a numbered sequence: decision to go around and full power, establish climb and positive rate, follow the published track and altitude, configure as required, then proceed to the holding fix or as instructed. Practise reciting it for three different charts until the order is automatic, and always check the published missed approach before commencing the approach.
Answering principles-of-flight questions about turns, load factor or stability by reasoning from the aircraft's attitude in a diagram-free description, rather than from the balance of lift, weight, thrust and drag and the effect of bank angle on load factor and stall speed.
Candidates rely on visual intuition from flying, which is unavailable in a text-only question, and forget that in a level turn the vertical component of lift must equal weight, increasing load factor and stall speed.
What to do instead
For every manoeuvre question, draw the force diagram in words: identify the flight path, then the forces along and perpendicular to it. Learn that load factor increases with bank angle in a level turn and that stall speed increases with the square root of load factor. Check each answer against the force balance rather than against how the manoeuvre feels.