CARC PPL Theory common mistakes
CARC PPL Theory · Understand the traps and how to avoid them.
Calculating crosswind and headwind components with a quick mental approximation and then choosing an answer without checking it against the runway limit, so a component of 18 kt on a 15 kt crosswind limit is accepted because the arithmetic 'felt right'.
Candidates practise the sine/cosine table but never build the habit of comparing the result with the stated aircraft or runway limitation, and under time pressure they round in the direction that makes the answer look plausible.
What to do instead
Work every wind component in a fixed three-step routine: write the angle, read the sine and cosine factors, compute both components, then state explicitly 'crosswind X kt versus limit Y kt' before looking at the options. Practise 20 mixed cases with a printed wind component chart until the comparison step is automatic.
Treating the mass and balance calculation as a single total-mass check and ignoring the centre of gravity position, or using the wrong datum sign convention so a load behind the datum is entered as negative.
Total mass is a single number that is easy to verify, whereas moments require consistent sign discipline; candidates who memorise 'arm times mass' without a diagram of the datum and station arms lose track of which side of the datum each station lies.
What to do instead
Before any arithmetic, sketch the datum, the fore and aft limits and each station arm on paper, and mark the sign of every arm. Compute total moment, divide by total mass, and plot the result on the envelope. Do at least five full load sheets including one with a forward and one with an aft out-of-limit result so the sign errors surface in practice rather than in the exam.
Reading a take-off or landing distance chart at the intersection of the wrong lines, for example using the pressure altitude line where the temperature line belongs, or forgetting to apply the subsequent wind, slope and surface corrections in the order the chart requires.
These nomograms have several families of parallel lines and the candidate is concentrating on the final number rather than on the sequence of entries; the chart's own worked example is often skipped during revision.
What to do instead
Learn the entry order for each chart as a written checklist and apply it identically every time: pressure altitude, then temperature, then mass, then wind, then slope, then surface. Trace each step with a ruler and write the intermediate value at each stage so a misread line is visible. Rehearse with the chart's own sample problem until the sequence is automatic.
Quoting a cruising altitude or flight level that is correct for the magnetic track but wrong for the quadrant, or applying the semi-circular rule using true track instead of magnetic track.
The rule is learned as 'odd hundreds eastbound' without the qualifier that the track must be magnetic and that the quadrant boundaries are 000 to 179 and 180 to 359 degrees; variation is then forgotten when converting from a plotted true course.
What to do instead
Always convert planned true track to magnetic track first, write the resulting magnetic track on the plan, then apply the quadrant rule to that figure. Memorise the quadrant boundaries explicitly and practise ten conversions where variation is deliberately large so that using true track produces an obviously wrong level.
Computing a heading without applying the correct sign of variation and deviation, for example adding westerly variation when converting from true to magnetic, or applying deviation to a magnetic heading instead of to a compass heading.
The mnemonics 'variation west, magnetic best' and 'deviation east, compass least' are remembered as phrases but not tied to a direction of conversion, so the candidate applies the right rule in the wrong direction.
What to do instead
Draw the true, magnetic and compass rose as three concentric scales on every navigation question and mark the direction of conversion with an arrow. State the conversion chain aloud: true to magnetic by variation, magnetic to compass by deviation, and reverse each sign on the way back. Work ten problems in both directions until the arrow, not the rhyme, drives the sign.
Answering human performance questions from everyday intuition, for example assuming that a tired pilot will notice fatigue, or that a low workload is restful, rather than applying the specific concepts of habituation, complacency and the inverted-U relationship between arousal and performance.
The domain reads like common sense, so candidates skim the model names and rely on personal experience; the exam, however, tests the defined mechanisms and their operational consequences.
What to do instead
Build a one-page table of the named models and effects with a one-line operational example each: arousal versus performance, vigilance decrement, habituation, spatial disorientation types, hypoxia onset with altitude, and the symptoms of hyperventilation versus hypoxia. Test yourself by explaining each example in a single sentence without notes.
Confusing the symptoms of hypoxia with those of hyperventilation, or choosing an action for a depressurisation that does not put the oxygen mask on first before descending.
Both conditions produce dizziness, tingling and confusion, and candidates memorise symptom lists without the distinguishing feature that hyperventilation improves with slower breathing while hypoxia requires oxygen and descent.
What to do instead
Learn the two conditions as a contrast pair: hypoxia is relieved by 100 per cent oxygen and descent, hyperventilation by controlled slow breathing and reassurance. Memorise the depressurisation drill as an ordered sequence, mask on, establish communication, then descend to the appropriate altitude, and rehearse the order until it is recited without hesitation.
Mixing up QNH, QFE and standard pressure settings, for example using QFE for a flight level or forgetting to reset the altimeter to standard when climbing through the transition altitude, leading to an incorrect terrain clearance calculation.
The three settings differ only in the reference surface and the error is invisible in cruise; candidates learn the definitions but not the operational rule about where each is used and when the change is made.
What to do instead
Write a short rule card: QFE reads height above the aerodrome, QNH reads elevation above mean sea level, standard 1013.25 reads flight level, with the transition altitude and transition level marked between the last two. For every altimetry question, state which reference the question is using before calculating, and practise pressure error problems where the setting differs from standard by a known amount.
Misreading a weather report or forecast by confusing groups, for example taking the validity period as the observation time, or missing that a trend group applies to the trend period rather than to the whole report.
Coded reports are dense and the candidate parses familiar groups quickly while skipping the ones that carry the timing and change information, which are exactly the groups the question depends on.
What to do instead
Decode every report in a fixed order: type and station, time, wind, visibility, weather, cloud, temperature and dewpoint, pressure, then trend or change groups. Write the decoded plain-language version out in full before answering. Practise with reports containing BECMG and TEMPO groups and state the start and end of each change explicitly.
Answering air law and radiotelephony questions from a general sense of what sounds professional rather than from the prescribed phraseology, for example reading back a clearance in paraphrased words or omitting the call sign from a readback.
The candidate has heard real radio traffic and assumes fluency is what is tested, but the examination tests the standard phraseology and the mandatory readback items, which are defined precisely.
What to do instead
Learn the mandatory readback list as a checklist: route clearance, runway, hold short instruction, altitude or flight level, heading, speed, frequency and transponder code, each followed by the aircraft call sign. Practise writing out full exchanges, including the call sign after every readback, and compare against the standard phraseology tables rather than against memory of live transmissions.