Fuel Planning, Payload & Loading

A. range can be increased only by trading payload for fuel (take-off mass limited), up to the point where the tanks are full

Up to the first corner the aircraft carries full payload; beyond it MTOM is reached, so every extra kg of fuel costs a kg of payload; beyond full tanks, range increases only as payload (mass) is shed further.

B. 200 kg/h

The burn is given in kg/h, which is a mass flow. The engine burns a mass of fuel for the power it makes, so a change of fuel density changes the volume used, not the mass: the burn stays 200 kg/h.

A. 30.3US gal/hr

Fuel available for the trip = 60 - 12 = 48 US gal over 1 h 35 min (1.583 h): 48 / 1.583 = 30.3 US gal/h.

A. 10,000 kg

Take-off fuel cannot exceed MTOM - ZFM = 14,000 kg. Of that, 4,000 kg must remain as reserves, leaving at most 10,000 kg of trip fuel.

A. 3.785 and 4.546

US gal x 3.785 = litres; Imp gal x 4.546 = litres; 1 Imp gal = 1.2 US gal.

The question was recalled without its options; these options were written to it.

C. 42195 kg

At the alternate the aeroplane still carries the final reserve and the unused contingency fuel; only the alternate fuel has been burnt. Landing mass = 33,510 + 7,600 + 983 + 102 = 42,195 kg (and at the destination it would be 1,100 kg more, 43,295 kg).

B. the approved one-engine-inoperative cruise speed in ISA and still-air conditions

The ETOPS threshold and maximum diversion distance are fixed figures: diversion time at the approved OEI cruise speed in standard (ISA), still-air conditions.

C. 77,800 kg

Taxi 600 + trip 6 x 10,000 = 60,000 + contingency 5% = 3,000 + alternate 10,200 + final reserve 30 min x 8,000 = 4,000 = 77,800 kg.

A. 13,000 kg

MZFM: 28,000 - 15,000 = 13,000. MTOM: 40,000 - 9,000 fuel - 15,000 = 16,000. MLM: 32,000 - 1,500 remaining fuel - 15,000 = 15,500. The lowest is 13,000 kg.

The question was recalled without its options; these options were written to it.

A. 15,000 kg

For an isolated destination a turbine aeroplane carries fuel to fly for 2 hours at normal cruise consumption above the destination, including final reserve: 2 x 7,500 = 15,000 kg.

The question was recalled without its options; these options were written to it.

A. DOM + traffic load

ZFM = dry operating mass + traffic load; + take-off fuel = TOM; + taxi fuel = ramp/taxi mass.

The question was recalled without its options; these options were written to it.

A. 160 kg

Fuel used = fuel flow x time = 120 x 1 h 20 min (1.333 h) = 160 kg.

The question was recalled without its options; these options were written to it.

C. the remaining fuel is insufficient to reach destination with the required reserves intact

Required reserves = 3.25 + 17 = 20.25 US gal. Half the trip used 40 (planned 32.5), so the second half also needs 40: 93 - 80 = 13 US gal at destination - below 20.25. It reaches destination, but not with reserves intact; plan a diversion or refuel.

The question was recalled without its options; these options were written to it.

C. the bending moment at the wing root.

On an aeroplane with wing tanks only, MZFM is set by the wing-root bending moment: the fuel in the wings relieves it.

C. 15900 Kg

Ramp fuel is limited by the tanks (16,100 kg); taxi fuel 200 kg leaves 15,900 kg for take-off. The mass limit (66,200 - 33,500 - 7,600 = 25,100 kg) is not limiting.

B. fuel

Payload is the traffic load (passengers, baggage, cargo); fuel is not part of it.

D. 4 HR 19 MIN

90 imp gal x 1.2 = 108 US gal; 108 / 25 = 4.32 h = 4 h 19 min.

B. with no usable fuel, unless the flight manual says otherwise

MZFM limits the mass in the fuselage (wing-root bending): above it, extra load must be fuel in the wings. Unusable fuel is counted in it.

The question was recalled without its options; these options were written to it.

B. 151 litres / 109 kg

40 US gal x 3.785 = 151 litres; x 0.72 = 109 kg.

The question was recalled without its options; these options were written to it.

A. passengers, baggage and cargo (including non-revenue load)

Traffic load/payload = everything carried for reward or delivery. Dry operating mass + traffic load = zero fuel mass; + take-off fuel = take-off mass.

The question was recalled without its options; these options were written to it.

B. basic empty mass + variable load (crew and their baggage, catering, removable service equipment)

DOM = everything needed for the operation except usable fuel and traffic load. Payload is added on top to get the ZFM.

The question was recalled without its options; these options were written to it.

C. TOM minus useful load.

DOM = TOM minus useful load (traffic load plus usable fuel).

C. 220 kg/hr

Fuel consumption in kg/hr is a mass flow, and the engine needs the same mass of fuel for the same power whatever the density. Only the volume (litres per hour) changes, so the consumption stays 220 kg/hr.

A. 11100

Zero-fuel mass 35,500 + 14,500 = 50,000 kg. Landing limit 56,200 - 50,000 = 6,200 kg at landing, plus trip 4,900 = 11,100 kg; the take-off limit gives 14,400 kg, so 11,100 kg governs.

A. 83 Imperial gallons

Imperial gallon is larger: 1 US gal = 0.833 Imp gal, so 100 US gal = 83 Imp gal (= 379 litres).

B. Estimated landing mass at destination: 43,295 kg

Landing mass at destination = DOM 33,510 + traffic load 7,600 + final reserve 983 + alternate 1,100 + contingency (5% of 2,040 = 102) = 43,295 kg.

A. 3,000 kg

Zero-fuel mass 50,000 kg against MZFM 53,000 leaves 3,000 kg; the take-off and landing limits leave more.

A. 4,300 kg

The correct answer is: 4,300 kg.

B. decreases

The same mass occupies more volume, so the mass per litre falls. Quantity by mass (kg) is unchanged - which is why fuel is planned in mass.

C. 13000 kg

Trip 5,350 + contingency 5% (268) + alternate/go-around 4,380 + final reserve 30 min at 6,000 = 3,000 = about 13,000 kg.

A. 1, 2, 3, 4

Fuel planning must allow for wind, foreseeable airborne delays, weather forecasts and any conditions that may delay landing.

B. ZFM + total fuel on board including taxi fuel

Ramp mass = take-off mass + taxi fuel = ZFM + block fuel. It is the heaviest the aircraft is on the ground.

The question was recalled without its options; these options were written to it.

D. 56100 lb

Start of cruise 65,000 - 4,500 = 60,500 lb; end of cruise 49,750 + 1,950 = 51,700 lb; mid-cruise = 56,100 lb.

A. 109 kg

40 US gal = 151 L; x 0.72 = 109 kg.

B. 360 LB

3/4 of 310 USG = 232.5 USG = 880 L = 686 kg; to reach 850 kg add 164 kg = 361 lb.

C. 39.5 US Gal/hr

146 imp gal / 4.433 h = 32.9 imp gal/h = 39.5 US gal/h (1 imp gal = 1.2 US gal).

A. 25.3 US Gal / HR

160 US gal / 3.167 h = 50.5 US gal/h for two engines = 25.3 US gal/h per engine.

C. 1000 kg

Fuel at take-off = 550 - 50 = 500 kg; TOM limit 3,500 - 2,000 - 500 = 1,000 kg payload (ZFM limit would allow 1,500).

B. 69 600 kg

Maximum zero-fuel mass 48,000 + reserves (900 + 700 + 2,000) = 51,600 kg landing mass, within the 56,000 limit; TOM = 51,600 + trip 18,000 = 69,600 kg (taxi fuel is burnt before take-off).

D. 1223 kgs

345 imp gal x 4.546 = 1568 litres; x 0.78 = 1223 kg.

A. 1123 kg

380 x 3.785 = 1438 litres; x 0.78 = 1122 kg.

The question was recalled without its options; these options were written to it.

A. 235 l/h

Mass flow = 220 x 0.80 = 176 kg/h. Lighter fuel needs more litres: 176 / 0.75 = 235 l/h. (If the pump fixes the VOLUME instead, the mass flow falls - a different question.)

The question was recalled without its options; these options were written to it.

A. 17,420 kg

Tank capacity = 22,560 x 0.781 = 17,620 kg; less 200 kg taxi = 17,420 kg at take-off. MTOM would allow 66,000 - 43,500 = 22,500 kg, so the tanks limit.

The question was recalled without its options; these options were written to it.

A. 90,830 lb

1407 + 8743 x 4.25 (37,158) + 9800 x 5.333 (52,267) = 90,832 lb.

A. 43,288 kg

At destination only the reserves are left: ZFM 41,110 + alternate 1,190 + final reserve 988 = 43,288 kg.

The question was recalled without its options; these options were written to it.

B. 13000

Trip 5,325 + contingency 5% (266) + alternate 4,380 + final reserve 30 min at 6,000 = 3,000 = about 13,000 kg.

B. 7.0 t

The traffic load can only fill the gap between the dry operating mass and the maximum zero fuel mass: 13.5 t - 6.5 t = 7.0 t (fuel is not part of the zero fuel mass).

C. 17500 kg

ZFM limit gives 60,000 - 42,000 = 18,000; landing limit: ZFM + 3.5 t reserve <= 63,000 gives 17,500; take-off limit 20,000. The landing limit governs: 17,500 kg.

A. 16,100 kg

ZFM = 41,100 kg, so MTOM would allow 66,200 - 41,100 = 25,100 kg of take-off fuel - more than the tanks hold. The tank capacity, 16,100 kg, limits it (15,900 kg at take-off after taxi).

A. take-off and landing mass both rise by 2,000 kg and trip fuel increases slightly

The extra 2,000 kg is carried throughout: TOM up by 2,000; the heavier aircraft burns a little more trip fuel, and almost all of the extra is still on board at landing.

C. 17 t

Maximum payload = MZFM - DOM = 60.5 - 43.5 = 17 t.

C. 3,000 kg

Traffic-load limits: MZFM 53,000 - 35,500 = 17,500; MTOM 64,400 - 7,400 - 35,500 = 21,500; MLM 56,200 - 2,500 - 35,500 = 18,200. The lowest, 17,500, governs; 17,500 - 14,500 = 3,000 kg more.

A. landing mass + trip fuel

Trip fuel is burnt between take-off and landing, so TOM = landing mass + trip fuel (and landing mass = TOM - trip fuel).

A. the dry operating mass plus the take off fuel mass

Operating mass is the dry operating mass plus the take-off fuel mass.

A. ZFM = DOM + take-off fuel

The correct answer is: ZFM = DOM + take-off fuel.

A. 15,550 kg

MZFW limit: 62,600 - 45,680 = 16,920. MTOW limit: 76,850 - 15,620 - 45,680 = 15,550. The smaller, 15,550 kg, governs.

A. 30 minutes at holding speed at 1500 ft above the alternate (destination) aerodrome, ISA

Turbojet: 30 min holding at 1500 ft; piston: 45 min (VFR/IFR differ). Planned fuel = taxi + trip + contingency + alternate + final reserve (+ additional + extra).