# Calculating fuel to load, and crusie level (etc).?

Quite often we see questions here about 'How much fuel?' 'How long can an aircraft fly?' 'What earns more - self-loading cargo or loaded cargo?'. Often, the experienced contributors (pilots) give a generalised answer, and often a lot of it boils down to 'depends' on a lot of... show more Quite often we see questions here about 'How much fuel?' 'How long can an aircraft fly?'

Often, the experienced contributors (pilots) give a generalised answer, and often a lot of it boils down to 'depends' on a lot of things.

So, my question is a challenge. I'm sure it's one pilots learn to do during training, and thereafter it is mostly (?) done by tapping the info into the computer and pressing the 'Gimme answer' button.

Scenario. (See end of question full full technical spec of the aircraft).

B737-400.

You are routing from Point A to B to C. Airfields at points A and C are at sea level. Point B is at 5000ft AMSL. Points A,B,C are in a plumb line direct line. Between point B and C - you have to get over a 10,000ft peak within 5 mins of departure. Thereafter it is 'downhill' to Point C which is at sea level.

Temperature between Point A is Ground = 20c, B is Ground = 35c, C is 20c, No winds/jetstreams.

Crew = 2 flight deck, 4 cabin.

Aicraft has just recently been through overhaul and tanks are completely empty. Last snagging list reported faulty fuel readings.

Engineers report states that 'faults rectified'

Point A to B. Distance 2200 nautical miles. Nearest alternate to Point B is 200 nautical miles.

Passengers onboard = 80
Passenger baggage = 800kg
Cargo you can load = unlimited - assume earn rate of 1 GECU per KG/unit area of cargo.
Cost of fuel at Point A = 1 GECU/litre

Point B to C. Distance 1500 mautical miles. Nearest alternate to Point C is 100 nautical miles.

Passengers onboard = 160
Passenger baggage = 2400kg
Cargo you can load = unlimited - assume earn rate of 0.5GECU per KG/unit area of cargo.
Cost of fuel at Point B = 3 GECU/litre !!!!

1 GECU = One Global Economic Currency Unit.

So, essentially, the question is, is it cheaper to load up with lots of fuel so that you do not need to buy so much expensive fuel at Point B, and a few other variables thrown in for good measure.

Your company will reward you 50% of the profit it makes on arrival in point C, after paying for fuel - and raking in whatever you've earned from cargo ops.

I hope the below is all the technical data you need, and I'm sorry if I've missed important data out, or the imaginary figues I've quoted are totally off-the-wall. I'm not a pilot.

Have fun. Best answer goes to whoever makes the best reasoned profit statement.

Series B737-400
Powerplant:
Model CFM56-3
Type C-1
Static Thrust (kN) 104.5
Static Thrust (Lb) 23,500
Bypass Ratio 4.9
EGT Margin (C) 45
Operational Items:
Accomodation:
Max certified seating 188
Hold volume (m³) 38.9
Volume per Passenger 0.22
Std Weights (kg):
Max. ramp 63049
Max. take-off 62822
Max. landing 54885
Max. zero-fuel 51256
IGW Weights:
Max. ramp 68266
Max. take-off 68039
Max. landing 56245
Max. zero-fuel 53070
Fuel capacity (ltrs) 20103
Fuel capacity (kg) 16200
Typical DOW 35100
Weight Ratios:
Ops Empty/Max T/O 0.516
Max Fuel/Max T/O 0.237
Fuel (litres):
Standard 20105
Optional 23829
Performance:
Thrust/Weight Ratio 0.3133
Take-off (m):
ISA s.l. 2540
ISA +20ºC s.l. 2665
ISA 5,000ft 2932
ISA +20ºC 5,000ft 4005
Landing (m):
ISA s.l. 1540
Speeds (kt/Mach):
V2 F5 at MTOW 167
Vref F40 at MLW 139
Vmo/Mmo 340/0.82
CLmax (T/O @ MTOW) 2.02
CLmax (Land @ MLW) 2.76
Long range cruise:
IAS / Mach 250/0.745
TAS (kt) 430
Ceiling (ft) 37000
L.R. Fuel flow (kg/h) 2377
Range with max payload (nm) 2800
Design Parameters:
(W/S)/CLmax 2296
W/SCLtoST 2792
Seat x Range (seats.nm) 469800