Mass, Balance, Payload and Centre of Gravity
MTOM, actual operating mass, payload security and the stability effects of centre-of-gravity changes.
How to prepare for the CAA A2 CofC
Learn the applicable aircraft route first, then connect weather and performance limits to site planning, separation, practical drills and safe operational decisions.
Core concepts
Concept 1
Maximum take-off mass is a limit that includes the aircraft, batteries, payload and every item carried at take-off.
Exam cue: Add every installed or carried item when comparing actual take-off mass with MTOM.
Concept 2
Payload mass and position can shift the centre of gravity, change stability and control demand, and reduce endurance or performance margin.
Exam cue: Consider where a payload is mounted, not only how much it weighs.
Concept 3
Gimbals, sensors and other loads must be compatible, securely attached and included in the pre-flight mass-and-balance assessment.
Exam cue: Treat a loose or incompatible payload as a flight-safety defect even if the mass remains below MTOM.
Risk pitfalls and guardrails
Using empty aircraft mass instead of total take-off mass.
Guardrail: Do not treat a certificate, automated function or minimum distance as permission to ignore current class, airspace, weather, performance or overflight restrictions.
Assuming a centrally mounted payload cannot affect performance.
Guardrail: Do not treat a certificate, automated function or minimum distance as permission to ignore current class, airspace, weather, performance or overflight restrictions.
Ignoring a small shift in centre of gravity on a sensitive fixed-wing or hybrid aircraft.
Guardrail: Do not treat a certificate, automated function or minimum distance as permission to ignore current class, airspace, weather, performance or overflight restrictions.
Memory anchors
MTOM
Maximum take-off mass includes the aircraft, battery, payload and all equipment carried at take-off.
Actual Mass
The planned take-off configuration must remain within every applicable mass limit.
Centre of Gravity
Payload position can shift the centre of gravity and change stability and control demand.
Payload Security
A payload must be compatible and secured so that it cannot move, detach or obstruct the aircraft.
Gimbal Effect
A gimbal adds mass, drag, power demand and a possible centre-of-gravity shift.
Performance Margin
Additional mass commonly reduces endurance and may alter climb, stopping and recovery performance.
Checkpoint rule
Do the check-up only after you can summarize each concept in one sentence and identify one dangerous pitfall from memory.
Knowledge Check (after reading)
Short check-up to confirm understanding of this module.
Check-up Questions
What must be included when calculating actual take-off mass?
An aircraft weighs 2.8 kg ready to fly and receives a 1.3 kg payload. Its MTOM is 4.0 kg. Is it within MTOM?
Answer all questions to submit.
Next step personalized recommendations
Continue learning
Move forward only after this module is stable.
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