Brunei DCA CPL(A) Flight Planning common mistakes
Brunei DCA CPL(A) Flight Planning · Understand the traps and how to avoid them.
Computing the navigation-log leg time by dividing distance by TAS but leaving the wind out of the calculation entirely, then carrying that uncorrected time into the fuel figures.
Candidates learn the triangular wind solution in isolation and, under time pressure, default to the simpler distance/TAS mental shortcut, forgetting that heading and groundspeed must come from the wind triangle before any timing or fuel number is produced.
What to do instead
Adopt a fixed worksheet order for every leg: true track, wind velocity, true heading and groundspeed via the triangle, then variation/deviation to compass heading, then time from groundspeed. Never write a time down until the groundspeed box is filled, and cross-check that headwind legs are slower than still-air time and tailwind legs faster.
Adding the contingency percentage to the wrong fuel figure, or applying it to trip fuel only after the alternate and final reserve have already been summed.
The fuel plan is often built as one long addition, so the contingency line gets inserted wherever the calculator happened to be, rather than as a defined percentage of trip fuel alone.
What to do instead
Build the fuel plan in a strict vertical column with labelled rows: taxi, trip, contingency (a stated percent of trip only), alternate, final reserve, additional, extra, total. Compute the contingency on its own line before adding anything else, and re-add the column bottom-up as a check.
Using the aerodrome elevation instead of the pressure altitude for the take-off or landing distance chart, or forgetting to apply the QNH correction when elevation and QNH differ significantly.
Elevation is the number printed most prominently on the chart page and in the AIP, so it is grabbed first; the pressure-altitude correction step is a small arithmetic operation that is easy to skip when the chart's entry axis is simply labelled 'pressure altitude'.
What to do instead
Write 'PA = elevation + 30 x (1013 - QNH)' (or the metric equivalent) as a standing line at the top of every performance question and fill it in before opening the chart. If QNH is within a few hectopascals of 1013, say so explicitly to show the correction was considered.
Treating the maximum structural landing mass as the only landing limit, ignoring the climb-limited and runway-limited landing masses that may be more restrictive at the destination.
The landing-mass calculation is taught initially as a weight check, and the performance-limited masses are covered separately, so candidates do not automatically compare all three and take the lowest.
What to do instead
For every landing question, list all applicable limiting masses side by side (structural MLW, climb limit, approach/climb limit, runway limit at destination, and any en-route limit) and select the lowest. State in the answer which limit was decisive.
Reading the chart's vertical axis at the wrong reference (for example using the aircraft category band for the wrong category, or interpolating between the wrong pair of grid lines) and then reporting a distance without checking it against a sanity range.
Performance charts use dense grids with several overlaid variables, and candidates rush to the intersection without confirming which line belongs to which variable or category.
What to do instead
Before reading any value, annotate the chart axes aloud in the working: variable, units, aircraft category, and configuration. After obtaining the answer, test it against an obvious bound (for example, does the landing distance exceed the available runway, and is the result plausible for the weight?).
Computing the mass and balance moment arms from the wrong datum or mixing station arms given in inches with those given in metres, producing a centre of gravity that looks acceptable but is wrong.
Load sheets and type data may quote arms relative to different datums, and unit mixing is invisible when the arithmetic is done quickly on a calculator without units written down.
What to do instead
Write the datum and the unit next to every arm and moment before multiplying. Convert all arms to one unit first, sum moments, divide by total mass, then compare the result against the envelope in the same unit system, and confirm the CG moves in the direction expected when load is added forward or aft.
Planning an RNAV route or waypoint without checking that the point lies within the navigation specification's coverage, that the required equipment (for example GNSS with the correct RNP value) is serviceable, or that the airway is approved for the planned equipment.
Candidates treat the route as a line on a chart and assume any published waypoint is usable, overlooking the difference between conventional and PBN routes and the equipment annotations in the AIP.
What to do instead
For each RNAV segment, verify three things explicitly: the navigation specification required, the aircraft's certified capability and RNP value, and any AIP note restricting the route. If any cannot be confirmed, plan a conventional alternative and note the reason.
Copying NOTAM or AIP data into the flight plan without checking its validity period and applicability against the estimated time over the affected point, so an expired or not-yet-active restriction is applied, or a live one is missed.
NOTAM lists are long and candidates scan for the aerodrome name rather than reading the effective times and the nature of the restriction against their own timeline.
What to do instead
For every NOTAM considered, write the from/to times beside the relevant leg time and mark it active, expired, or future. Only active items change the plan; future items go in a note with the time they become relevant.
Deciding to divert or replan only after the destination weather has already fallen below minima, rather than setting a defined decision point and fuel state in advance.
Candidates answer diversion questions retrospectively, describing what should have been done, instead of stating a trigger and a plan; the human-factors element of pre-briefed criteria is not practised.
What to do instead
For any in-flight scenario, state a concrete trigger (a fuel figure, a time before ETA, or a reported weather value), the decision point, and the chosen alternate with its fuel and performance check. Answer in the form 'if X by time Y, then Z'.
Filing an ATS flight plan with a route field or fuel endurance that does not match the operational plan, or omitting the alternate and the total EET in the correct fields.
The ATS form is treated as an administrative afterthought, filled from memory rather than transcribed from the completed operational plan, and the field meanings are not rehearsed.
What to do instead
Transcribe the ATS plan directly from the finished operational plan, field by field, and then read it back against it: route string, destination, alternate, total EET, and endurance in the correct format. Practise the field order until it is automatic.