This lesson is the arithmetic heart of the loading chapters: given an aircraft, a route and a fuel plan, how heavy may the flight actually be, and how much payload does that leave? The method never changes. Work out every ceiling that could bite, translate each into a take-off mass, take the lowest, and subtract what the aircraft and its fuel already weigh. What remains is the traffic load the flight is allowed to sell. The lesson closes with the standard passenger and baggage masses the regulations allow instead of weighing everyone, because they are what turns a booking list into kilograms.
The allowed take-off mass
Three ceilings can cap the take-off mass, and each must be converted into the same currency, a mass at brake release, before they can be compared:
The take-off limit itself — the regulated take-off mass: the lower of the maximum structural take-off mass and the performance-limited take-off mass for the departure runway.
The zero-fuel limit, carried forward — the MZFM plus the take-off fuel. If the aircraft took off heavier than this, its mass minus its usable fuel would have to exceed the MZFM, which no loading is allowed to do.
The landing limit, carried backward — the regulated landing mass (the lower of the structural and performance-limited landing masses) plus the trip fuel. Take off heavier and the aircraft would arrive at the destination above its landing ceiling even with the flight flown exactly as planned.
The allowed take-off mass is the lowest of the three. Nothing in the definition says which one wins: on a short sector with little trip fuel the landing limit often bites, on a full-tanks long haul the zero-fuel limit can, and on a hot day at a high aerodrome the take-off performance usually does. The exam's favourite trap is offering the regulated take-off mass as the answer when one of the other two ceilings is lower, which is why the three-line comparison should be written out every time.
Check you understood
Three questions from this lesson — one straightforward, one that applies it, one that pushes a little further. Nothing is recorded, and you can draw a new set as often as you like.
1. Warm-up
Under the EASA standard masses, a flight crew member and a cabin crew member are counted at:
2. Applying it
An aeroplane has a maximum structural landing mass of 64,000 kg. The performance-limited landing mass at the destination is 62,300 kg. The regulated landing mass, and the highest take-off mass it permits with a trip fuel of 11,600 kg, are:
3. Pushing it
A flight's traffic load is fixed by a freight contract. The allowed take-off mass is 70,400 kg, the DOM 40,100 kg and the traffic load 18,700 kg. The most take-off fuel that may be carried is:
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What you are looking at: the three ceilings of one worked departure, each converted into a take-off mass and drawn as a bar to scale. The regulated take-off mass is 78,200 kg; the maximum zero fuel mass plus the take-off fuel comes to 78,500 kg; and the regulated landing mass plus the trip fuel comes to 77,700 kg. The dashed line sits on the lowest bar top: 77,700 kg is the allowed take-off mass, and on this sector it is the landing limit, not the take-off limit, that decides how heavy the flight may leave. The bars share a common truncated baseline, so the differences between the ceilings are to scale even though the full bar heights are not proportional to the absolute masses.
Allowed traffic load, underload and overload
Once the allowed take-off mass is known, the payload question is one subtraction. The operating mass, DOM plus take-off fuel, is everything the flight already weighs before a single passenger boards, so the allowed traffic load is the allowed take-off mass minus the operating mass. Comparing it with what the flight actually wants to carry gives the day's verdict: the underload is the allowed traffic load minus the actual traffic load, the spare capacity still available for freight, extra bags or late passengers. A negative result is an overload: the flight cannot go until that many kilograms of load or fuel are taken off. The same subtraction can also run through fuel: if the traffic load is fixed, the room left under the allowed take-off mass caps the fuel that may be carried instead.
Standard masses for passengers, baggage and crew
Weighing every passenger would make airline schedules impossible, so the regulations publish standard masses that may be used instead, and the exam expects them to be extracted and applied exactly. All values include hand baggage, and an infant travelling on an adult's lap is already inside the adult's figure; an infant occupying its own seat counts as a child. For crew, the standard masses cover the crew member and their hand baggage:
Crew — 85 kg for each flight crew or technical crew member, 75 kg for each cabin crew member.
Passengers, 20 seats or more — 88 kg per male, 70 kg per female on all flights except holiday charters; on holiday charters 83 kg and 69 kg. Children aged 2 to 12 count 35 kg on every kind of flight.
Passengers, 30 seats or more (alternative) — a single all-adult figure may be used instead of the male/female split: 84 kg, or 76 kg on a holiday charter.
Passengers, 19 seats or fewer — heavier per-head values from the small-aircraft table: 104 kg male and 86 kg female with 1 to 5 seats, 96 kg and 78 kg with 6 to 9 seats, 92 kg and 74 kg with 10 to 19 seats. If no hand baggage is carried in the cabin, or hand baggage is accounted for separately, 6 kg may be deducted per adult.
Fewer than 10 seats — passenger mass may instead be taken from each passenger's own statement, plus a predetermined allowance of no less than 4 kg for clothing and 6 kg for hand baggage.
Checked baggage, 20 seats or more — per piece by type of flight: 11 kg domestic, 13 kg within the European region, 15 kg intercontinental, 13 kg all other flights. With 19 seats or fewer, checked baggage must be weighed.
A holiday charter, for these tables, is a charter flight sold as part of a holiday travel package, with the entire passenger capacity hired by one or more charterers for round- or circle-trip holiday travel; up to 5 per cent of the seats used for certain non-revenue passengers does not disqualify the flight. Two more details in the fine print are exam favourites. The heavier per-head values for small aircraft exist because a small statistical sample cannot be trusted to average out: three heavy passengers in a six-seater shift the total far more than three hundred would in an airliner. And the choice between the male/female split and the all-adult figure is the operator's, but only where the seat count permits: the split needs 20 seats or more, the all-adult figure 30 or more.
Calculate the regulated take-off and landing masses and the allowed take-off mass as the lowest of RTOM, MZFM plus take-off fuel, and RLM plus trip fuel
Extract the standard masses for crew, passengers and baggage for a given aircraft size and flight type, including the holiday-charter and small-aircraft tables