CAA NZ IR Instruments and Navaids common mistakes
CAA NZ IR Instruments and Navaids · Understand the traps and how to avoid them.
Treating the instrument indications as independent truths rather than cross-checking pitot-static and gyroscopic sources, so a single failed source (e.g. a blocked static port) is misread as a real climb or descent.
Candidates learn each instrument in isolation during study and default to reading one gauge at a time; exam items deliberately present a single anomalous indication and expect the candidate to recognise the pattern of a specific failure.
What to do instead
Practise 'partial panel' reasoning: for each failure (pitot blockage, static blockage, gyro failure, suction loss), write out the exact resulting indications on ASI, altimeter, VSI, AI and DI, then rehearse the cross-check logic that isolates the failed source.
Confusing the behaviour of a blocked pitot tube versus a blocked static port, particularly what happens in climb and descent and what the ASI reads when the pitot drain/static is obstructed.
Both failures produce misleading airspeed and altitude information but in different ways; candidates memorise 'blocked pitot = bad ASI' without the directional detail the exam tests.
What to do instead
Build a table of climb/level/descent versus blocked pitot (with and without drain hole) and blocked static, and test yourself on each cell until the pattern is automatic.
Misapplying the gyroscopic instruments' source of power and failure indications, e.g. attributing attitude indicator and heading indicator errors to the wrong instrument when suction or electrical supply fails.
Vacuum/electrical systems, erection mechanisms and caging flags are abstract, and candidates skim the system description rather than learning which instrument depends on which source and how it fails.
What to do instead
Learn each gyro instrument by its power source, degrees of freedom, erection/levelling behaviour and specific failure indication (e.g. AI topple, DI drift, turn coordinator flag), and link each to the pre-flight and in-flight checks.
Selecting the wrong navaid or frequency for the situation, or failing to identify what a given navaid provides (e.g. treating a VOR radial as a bearing to the station, or misreading DME slant range as ground distance).
Radio navigation concepts (radial versus bearing, magnetic versus true references, slant range, line-of-sight limitations) are conceptually dense and candidates rely on rote frequency lists instead of understanding what each aid measures.
What to do instead
For VOR, DME, NDB/ADF, ILS and GNSS, write a one-line definition of exactly what is measured and its reference datum, then practise converting between radial, bearing, track and heading with wind included.
Misinterpreting ILS indications, especially localiser and glideslope sensitivity, false glideslope, and the difference between fly-up/fly-down and on-course indications at different ranges.
ILS is taught as 'follow the needles' without the underlying signal geometry, so candidates cannot answer questions about beam width, sensitivity changes with range, or abnormal indications.
What to do instead
Study the ILS signal structure (localiser beam width, glideslope angle, coverage, false glideslope at steep angles) and work through scenarios where indications become more sensitive as the aircraft approaches the threshold.
Confusing RNAV and RNP capabilities, particularly the meaning of on-board performance monitoring and alerting, and which operations require it versus which rely on ground-based or baro-aiding.
The RNAV/RNP distinction is a specification-level concept that candidates reduce to 'RNP is more accurate', missing the monitoring-and-alerting requirement that defines RNP.
What to do instead
Learn the definitions precisely: RNAV as area navigation without mandatory on-board performance monitoring, RNP as requiring on-board performance monitoring and alerting, and be able to state which navigation specifications apply to which airspace and procedure types.
Treating GNSS as infallible and failing to account for RAIM availability, receiver autonomous integrity monitoring predictions, and the effect of satellite geometry (HDOP/VDOP) on approach capability.
GNSS is presented operationally as a black box; candidates do not connect integrity monitoring, satellite geometry and the need for pre-flight RAIM prediction to actual go/no-go decisions.
What to do instead
Learn what RAIM detects and what it cannot, how satellite geometry affects the ability to detect faults, and rehearse the pre-flight integrity prediction step for a GNSS-based approach, including what to do if prediction fails.
Misreading RNP approach minima and the meaning of the RNP value in the procedure title, or assuming a lower RNP value is always available without the required equipment and approval.
Candidates skim the chart title and minima block, treating RNP 0.3 and RNP 0.1 as interchangeable, and overlook the aircraft/operator approval condition attached to each.
What to do instead
For each RNP procedure, identify the navigation specification, the required approval, the minima line and the missed approach, and state explicitly what happens if the aircraft cannot meet the specified performance.
Misreading instrument approach and departure charts, e.g. confusing plan and profile views, misidentifying the final approach fix, or misinterpreting minimum sector altitudes and step-down fixes.
Chart reading is a skill built through repetition; candidates memorise symbology lists rather than practising extracting a complete procedure from an unfamiliar chart under time pressure.
What to do instead
Practise reading full AIP New Zealand approach plates: trace the lateral path on the plan view, then the vertical path on the profile, then reconcile with the minima table and missed approach, narrating each fix and altitude.
Failing to locate and apply the correct AIP New Zealand documentation (e.g. using an out-of-date chart, missing a SUP or AIC amendment, or not knowing where to find a particular procedure or airspace classification).
Candidates study from memory or secondary summaries and do not build familiarity with the AIP NZ structure, so they cannot answer questions about where information lives or how amendments are promulgated.
What to do instead
Work through the AIP NZ table of contents and practise locating specific items (aerodrome charts, en-route supplements, AICs, SUP status) so the document structure and amendment process become familiar.