Weighing & standard masses

031 Mass & BalanceChapter 7

Operators use actual weighing or approved standard masses to establish traffic load. Weighing intervals and sample sizes are regulated — standard masses depend on seat count.

Weighing procedures

Key fact

Aircraft are weighed on a minimum of 3 points of support. Small aircraft use scales; large aircraft use electronic pressure pads. Weighing is done in an enclosed building with no air conditioning effects on the scales.

Key fact

Not required for weighing: draining all engine oil, or ensuring all fuel/oil tanks are full (fluids are accounted for per manual). Aircraft weighed fully equipped in standard role — includes unusable fuel/oil, operating fluids, fire extinguishers, pyrotechnics, emergency oxygen, supplementary electronics.

Key fact

Tailwheel aircraft — weighed in flight attitude (level). BEM recorded in weighing schedule; amendments for modifications may be calculated rather than full re-weigh.

Weighing frequency

Key fact

Individual masses: each aircraft weighed every 4 years. Fleet masses: sample weighed every 9 years, but fleet mass must be re-determined at least every 48 months.

Key fact

Re-weigh when: initial entry, records not adjusted for mods, 48 months elapsed (unless fleet scheme), CG change exceeds ±0.5% MAC, DOM change exceeds ±0.5% MLM.

Fleet mass sample size

Key fact

Where n = fleet size, number of aircraft to weigh:

Fleet size	Sample
2–3	n
4–9	(n + 3) ÷ 2
10+	(n + 51) ÷ 10

Choose aircraft with the longest time since last weighed. Fleet DOM and CG values must not differ by more than ±0.5% between individual aeroplanes.

Standard crew masses

Key fact

Standard masses include hand baggage:

Role	Mass
Flight crew	85 kg each
Cabin crew	75 kg each

Some older references cite 84 kg flight crew — EASA AIR OPS standard is 85 kg inclusive of baggage.

Passenger masses — 20 seats or more

Key fact

Standard passenger masses include hand baggage — no deduction for hand baggage. Infant on adult’s lap — not counted. Infant in own seat — count as child (35 kg).

Key fact

Checked baggage standard masses (when allowed):

Route type	Baggage mass
Domestic	11 kg
Europe & others	13 kg
Intercontinental	15 kg

Standard baggage masses apply only to aircraft with 20 seats or more. Exceeded baggage must be actually weighed or mass increments added.

Passenger masses — 19 seats or fewer

Key fact

If hand baggage accounted separately or not carried: deduct 6 kg from male/female standard masses. Checked baggage must be determined by actual weighing — no standard baggage masses.

Key fact

With fewer than 10 seats, passenger mass may be established by: verbal statement, actual mass, or pre-determined masses from a survey.

Passenger categories

Key fact

Infant: under 2 years (on lap — excluded from mass). Child: 2 to 12 years — 35 kg regardless of sex. Adult: over 12 years — standard table masses from operator survey or EASA tables.

Key fact

Weighing machine for pax: capacity at least 150 kg, graduations 500 g. Operator must complete a detailed weighing survey approved by the competent authority before using standard masses.

Traffic load establishment

Key fact

Traffic load is established by actual weighing or standard masses per EASA AIR OPS. Total fuel loaded includes taxi fuel. Block fuel minus taxi = take-off fuel.

Exam trap

Standard baggage masses only for 20+ seats. For 19 or fewer, weigh checked bags — no standard baggage allowance table.

Exam trap

Infant on lap = zero mass. Infant in own seat = child = 35 kg. This distinction appears in almost every M&B exam.

Exam trap

Fleet mass interval: 48 months maximum between fleet evaluations, even though individual aircraft in a fleet scheme may go 9 years between being weighed.