NZ CAA PPL Navigation common mistakes
NZ CAA PPL Navigation · Understand the traps and how to avoid them.
Computing a navigation leg with the true track and true heading only, then flying it as though the magnetic values were the same, so the aircraft tracks a consistent number of degrees off the planned line.
Candidates learn the wind triangle in the classroom with true values and treat variation as a footnote. Under exam pressure they apply variation in the wrong direction or forget it entirely, especially when the chart shows variation at the edges rather than at the planned track.
What to do instead
Adopt a fixed written sequence for every leg: true track, wind correction to true heading, then apply variation to get magnetic heading, then apply deviation to get compass heading. Write each step in a column on the flight log so a missing line is visible. Practise with a chart where variation differs across the route.
Mixing units in the wind triangle, entering wind speed in knots against a true airspeed in km/h, or using a wind direction that is magnetic when the triangle needs true, producing a heading that is plausible but wrong.
New Zealand operators commonly work in knots while some aircraft and documents quote speeds in km/h or mph, and forecasts give wind in true degrees while ATIS and tower reports give magnetic. Candidates grab whichever figure is nearest without checking the label.
What to do instead
Before solving, write the units beside every input (TAS kt, wind 270/25 kt true) and convert once, at the start. Treat any wind quoted by ATC or ATIS as magnetic and convert to true before use. Build a habit of sanity-checking the crosswind component against the reported wind speed.
Plotting a track on the chart with a pencil line but reading the track direction at the wrong meridian, or measuring distance with the latitude scale from a different part of the chart.
On a Lambert conformal conic chart, grid convergence means the angle between grid north and true north changes across the sheet, and the scale is only strictly constant along standard parallels. Candidates measure at the edge of the chart or at the nearest compass rose without thinking about where the aircraft actually is.
What to do instead
Measure track at the meridian closest to the midpoint of the leg being flown, and note the convergence correction if the leg is long. Measure distance against the latitude scale at the same latitude as the leg. Re-check by measuring the leg in two halves and confirming they add up.
Planning a leg without a deliberate alternate and diversion airfield, or listing alternates that are not actually usable for the forecast conditions, then being unable to answer where the aircraft would go if the destination closed.
Candidates treat the flight plan as a fuel and track exercise and copy the nearest airfield without checking runway length, surface, opening hours, or forecast crosswind. The exam then probes the decision rather than the arithmetic.
What to do instead
For each destination, select one alternate and justify it in writing: distance, forecast weather at the expected arrival time, runway length and surface, and fuel required to reach it. State the diversion trigger in advance, such as cloud base below a nominated value or crosswind above the aircraft limit.
Treating the forecast wind as constant for the whole flight, so the heading and groundspeed computed for departure are still used two hours later after the wind has backed and strengthened.
Wind forecasts are valid for a period and a level, and candidates compute one wind triangle per leg and never revisit it. In flight they notice the drift but do not recalculate, and on paper they cannot explain how to update the plan.
What to do instead
Recompute heading and groundspeed at each turning point and at least hourly, using the forecast wind for the level and time actually being flown. In the air, use the difference between planned and observed drift and groundspeed to derive an updated wind and apply it to the next leg.
Using the GPS groundspeed and track as the sole means of position fixing and navigation, without a map-to-ground comparison or a cross-check against a second source.
Moving-map displays are compelling and candidates stop looking outside. They also do not appreciate that a GNSS position can be degraded, mis-set in datum, or that the unit may be showing a direct-to track rather than the planned track.
What to do instead
Maintain a deliberate cycle of map reading, timing, and radio aid checks alongside GNSS, and state in the plan how each leg will be confirmed. Confirm the receiver datum matches the chart, and treat any large unexplained difference between GNSS track and planned track as a reason to verify position by another method.
Flying a VOR radial or NDB bearing outbound when the plan required tracking to the station, or misidentifying which side of the selected course the aircraft is on, and turning the wrong way to intercept.
The to/from flag, the course selector, and the CDI deflection interact, and candidates learn the rules as slogans rather than as a mental picture. NDB relative bearings are worse because there is no course selector to anchor the interpretation.
What to do instead
Draw the station, the selected course, and the aircraft on a scrap of paper before turning. Use the rule that the CDI needle shows the direction of the selected course, so fly toward the needle, and confirm the to/from indication matches the intended direction. For NDB, convert relative bearing to magnetic bearing with the heading before deciding the turn.
Calculating fuel for the planned route only, omitting taxi, climb, contingency, and the reserve, and then presenting a total that cannot legally or practically be flown.
Candidates add cruise burn multiplied by time and stop there, forgetting that climb fuel is significant in a light aircraft and that reserves are defined by rule rather than by preference.
What to do instead
Build the fuel plan in named blocks: taxi, climb, cruise by leg, descent, contingency, alternate, final reserve, and any holding allowance. Show the figures so each block can be checked, and confirm the total against the aircraft's usable fuel and the required reserves for the flight.
Ignoring the effect of temperature and pressure on the altimeter and on true airspeed, so the flight is flown at a different height above terrain and at a different TAS than planned.
Candidates treat indicated altitude as height and use a single TAS figure from the manual. They do not connect low pressure or high temperature with the altimeter over-reading and with increased density altitude.
What to do instead
Set the correct pressure setting for the phase of flight and apply the rule that flying from high to low pressure, or into colder air, means the altimeter over-reads and true height is lower. Compute TAS from IAS, pressure altitude, and temperature for the planned cruise, and note the density altitude for departure and destination performance.
Producing a nav log with no times, no headings, and no fuel per leg, then being unable to answer follow-up questions about where the aircraft should be at a given time.
Candidates fill in the log mechanically from a flight computer without understanding what each column is for, so they cannot use it in flight or defend it in the oral.
What to do instead
Complete every column for each leg, including planned time overhead each turning point, and rehearse the in-flight use: at each checkpoint compare actual time and heading with plan, write down the difference, and revise the estimate for the next point. Be ready to explain any column on request.