AirCraft Mass Definitions

Question 1

Components of all-up mass

Answer 1

• basic empty mass
• variable load
• traffic load
• fuel

Question 2

Basic empty mass

Answer 2

• empty clean aircraft
• any unusable fuel
• the full quantity of operating liquids (such as engine oil and hydraulic fluid)
• safety equipment
• supplementary electronic equipment

Question 3

Variable load

Answer 3

• the crew and their baggage
• the catering and other removable passenger service equipment
• food and beverages
• potable water
• lavatory chemicals and any other special operational equipment

Question 4

Traffic load

Answer 4

Combined mass of passengers and their baggage

Plus cargo and non revenue load

Question 5

Dry operating mass

Answer 5

Basic empty mass + variable load

Question 6

Useful load

Answer 6

Traffic load + fuel on board at takeoff

Question 7

Operating mass

Answer 7

DRY OPERATION MASS;
(Basic empty mass + variable load)
+
Takeoff fuel

Question 8

Zero fuel mass

Answer 8

All components - the fuel

Basic empty mass + variable load + traffic load

Question 9

Max structural taxi mass / max ramp mass

Answer 9

Max mass of aircraft when it begins taxi

Limited by the stress on oleo shock absorbers and the strength of landing gear

Question 10

Max structural take off mass

Answer 10

Max mass at start of take off run

Less than max taxi mass as fuel has been used on start up and taxi

To prevent excess bending and wing roots

Question 11

Max in flight mass

Answer 11

Max inflight mass taking into account likely aerodynamic loads

Question 12

Max zero fuel mass

Answer 12

Max mass with no fuel

Question 13

Max structural landing mass

Answer 13

Max landing mass at landing in normal circumstances

Needing to take into account additional dynamic loads imposed by landing

Question 14

Performance limited take off mass

Answer 14

Max take off mass to comply with departure performance limitations

• runway distance available
• min climb gradients

Question 15

Performance limited landing mass

Answer 15

Max landing mass to comply with landing limitations

• runway distance available
• min climb gradient required in case of go around

Question 16

Regulated take off mass

Answer 16

Max take off mass taking into account structural and performance limitations

Question 17

Regulated landing mass

Answer 17

Max landing mass that complies with both structural and performance limitations

Question 18

Block fuel

Answer 18

Taxi fuel
Trip fuel 
Contingency fuel 
Reserve fuel 
- alternative reserve 
- final reserve 
Additional fuel 
Extra fuel

Question 19

Taxi fuel

Answer 19

Fuel used before take off

• Apu before start up
• Fuel used during start
• Fuel allowed for ‘reasonable’ taxi distance plus allowing for stationary time with engines running

Question 20

Trip fuel

Answer 20

Fuel planned to burn between departure and destination airport

Question 21

Contingency fuel

Answer 21

Allows for small changes in fuel burn caused by unexpected routing, cruise levels and changes in forecast wind

Question 22

Alternative reserve

Answer 22

Amount of fuel require from point of missed approach until landing at alternate aerodrome

Question 23

Final reserve fuel

Answer 23

Remaining fuel that must be on board at the planned landing at planned destination

Allows for holding at 1500ft for 30 mins in a jet aircraft (45 in piston)

Question 24

Additional fuel

Answer 24

Additional allowance to comply with specific requirements

Question 25

Extra fuel

Answer 25

Added by aircraft commander in anticipation of delays because of;

• poor weather
• peak rush hour time
• use of anti icing

Question 26

Max traffic load

Answer 26

Allowed take off mass 
=
Dry operating mass 
-
Take off fuel