EASA ATPL 033 Flight Planning common mistakes
EASA ATPL 033 Flight Planning · Understand the traps and how to avoid them.
When converting a magnetic wind into a true wind (or vice versa) for the wind triangle, the candidate adds or subtracts variation in the wrong direction, so every subsequent heading and ground speed is offset by twice the variation.
The memory aid 'east is least, west is best' is applied mechanically without checking which frame the wind is given in. MET wind is true, the flight plan heading is magnetic, and the candidate loses track of which quantity is being converted.
What to do instead
Write the conversion chain explicitly on the working sheet: MET true wind -> apply variation to get magnetic wind -> compute magnetic heading -> apply deviation to get compass heading. Check with a sanity test: a true wind from 270 with 10E variation becomes magnetic 280. Do this once at the start of every calculation and never convert mid-triangle.
The candidate computes a single drift and ground speed for a whole leg instead of splitting the leg at the point where the wind changes, or applies the average wind to a leg that crosses several forecast levels.
It feels faster to treat a 200 NM leg as one unit, and the candidate does not check whether the wind forecast varies along the route or with altitude.
What to do instead
Before any leg calculation, scan the wind table for changes in direction/speed between waypoints and between levels. Break the leg at each change point, compute each sub-leg separately, then sum time and fuel. If the wind is constant within 10 degrees and 5 kt, one calculation is acceptable; otherwise split.
The candidate uses the trip fuel figure from the flight-planning table but forgets to add taxi fuel, contingency fuel, alternate fuel and final reserve before comparing with the fuel load, so the aircraft is dispatched below the required minimum.
Trip fuel is the most visible number on the plan and the candidate treats it as 'the fuel'. The fuel policy components are listed in a separate table and get skipped under time pressure.
What to do instead
Build a fixed fuel ladder every time, in the same order: taxi + trip + contingency + alternate + final reserve + extra = total required. Compare total required against fuel on board, not trip fuel against fuel on board. Write the ladder on the answer sheet before starting the numerical work.
The candidate applies the contingency fuel as a percentage of the total fuel load rather than as a percentage of trip fuel, or applies it to the wrong reference leg.
The percentage is stated in the fuel policy text but the reference quantity is easy to misread; candidates also confuse contingency with the 5% figure used in some older or different regulatory contexts.
What to do instead
State the reference quantity in words before computing: 'contingency = 5% of trip fuel for the planned route'. Compute trip fuel first, then take the percentage of that single figure. If the rule allows a reduced contingency based on a decision point or a fuel-consumption monitoring programme, note which rule applies and why.
The candidate computes the alternate fuel using the alternate leg distance but uses the cruise fuel flow for the planned cruising level rather than the level actually flown to the alternate, or omits the missed-approach and go-around allowance.
Alternate planning is treated as a simple distance-times-flow calculation, and the candidate does not re-read the performance data for the alternate leg's level and mass.
What to do instead
Treat the alternate as a separate mini flight plan: level, wind, mass at the alternate, fuel flow from the cruise table, plus a missed-approach allowance if the operator's policy requires it. Write the alternate calculation on its own line so it cannot be absorbed into the trip fuel.
The candidate selects a cruising level that is not compatible with the semi-circular rule for the planned track, or ignores that the requested level is above the aircraft's maximum operating altitude at the planned mass.
The candidate focuses on wind and fuel efficiency and forgets that levels are allocated by track and that the performance ceiling changes with mass and temperature.
What to do instead
Check three things for every level: (1) semi-circular rule against magnetic track, (2) maximum operating altitude from the performance manual at the planned mass and temperature, (3) airspace restrictions along the route. If any fails, choose the next usable level and recompute fuel, because the fuel figure depends on the level actually flown.
The candidate calculates take-off and landing performance using the actual mass but forgets to apply the corrections for pressure altitude, temperature, wind, runway slope and contamination, or uses the wrong chart line for flaps.
Performance charts have multiple correction steps, and candidates stop after the first read-off because the answer looks plausible.
What to do instead
For every performance chart, list the correction sequence in the chart's own order: pressure altitude, temperature, wind component, slope, contamination, then flap setting. Apply each correction explicitly and write the intermediate value. If the chart gives a maximum mass rather than a distance, state which limit is binding.
The candidate computes the centre of gravity using the correct moment arms but omits one of the loading items (e.g. the fuel in the outer tanks, or the crew baggage), or uses the wrong arm for a compartment.
Loading tables have many rows and the candidate copies values quickly without cross-checking the total mass against the sum of the individual items.
What to do instead
After building the mass-and-moment table, sum the masses independently and compare with the total mass used in the CG calculation. Any mismatch means an item was missed. Then plot the CG against both the forward and aft limits for the actual mass, not just the maximum mass.
The candidate files or reads an ATS flight plan with the wrong route field syntax, missing the speed/level group, or placing the cruising level in the wrong field, and then cannot answer questions about what the plan actually authorises.
The flight plan form has strict field syntax, and candidates learn the fields as labels rather than as a sequence with rules about what goes in each.
What to do instead
Learn the field order as a fixed sequence (aircraft identification, rules, type, wake, equipment, departure, time, speed/level, route, destination, EET, alternates, fuel, persons, emergency equipment, remarks). Practise writing one complete plan by hand and check the speed/level group format (e.g. N0450F350) character by character.
In an ETOPS/EDTO equal-time-point or diversion question, the candidate computes the ETP using still-air distance or ignores the wind on the diversion leg, and does not check the critical fuel scenario against the ETP.
ETP geometry is unfamiliar, and the candidate applies the same simple distance/speed approach used for short-haul alternates.
What to do instead
For each ETP, set up the equation with the actual groundspeed outbound and the actual groundspeed on the diversion leg, including wind. Then check the critical fuel case (depressurisation, engine failure, icing, forecast winds) against the fuel available at the ETP. State which scenario is limiting and why.