Tankering of Fuel

[Doors to Automatic]

A friend of mine flew on a 2 hour 40 sector back to the UK on a 737-800 (189 seats) and did not observe any refuelling at the outstation, suggesting that the entire return sector was covered by fuel tankered in on the outbound.

I understand that the plane has an empty weight of 41 tonnes, and a max landing weight of 65 tonnes leaving 24 tonnes for pax, bags and fuel. Assuming around 18 tonnes for the pax and bags this only leaves around 6 tonnes.

Given a consumption of 2.4t per hour this trip would require almost 6 tonnes of fuel but reserves would take it over MLW on the inbound flight.

I just wondered how this is possible? Do some airlines have a higher MLW?

[FlyingStone]

Assuming around 18 tonnes for the pax and bags this only leaves around 6 tonnes.

Not all flights have high traffic load, especially with low cost carriers there are normally very few bags carried in the hold, comparing to the legacy airlines or long-haul flights.

Given a consumption of 2.4t per hour this trip would require almost 6 tonnes of fuel but reserves would take it over MLW on the inbound flight.

Tankered fuel counts into reserves for the first flight - if you have fuel on board, you can use it.

[737aviator]

While 100kg per pax & bag is a good mental gross error check, the actual weight is usually lighter, especially if there are a lot of children. Only on long holiday flights (e.g. Canary Islands from UK) do I see a lot of checked in bags; maybe 100 on a full flight, but then still a lot of children. So even if your friends inbound flight was full with 189 pax, it probably didn't have the same traffic load as you estimated.

[B737900er]

Max theoretical fuel that can be uplifted can be calculated by using said formulae.

Max uplift = MLW+trip-EZFW.

For tanking sectors you would take the min block fuel for the second sector plus 1st sector trip fuel and taxi.

Of course you will need to work out the RTow for both sectors to see fi your performance limited in anyway.

My outfit flies fully loaded majority of the time, and the payload comes to around 15-17t

[enicalyth]

just doodling for fun

Suppose EGNX – LPFR, 1050 nam at 447ktas and FL330-370 with a second alternate at 180 nm. Winds are light, almost negligible; temperature 18*, CAVOK 9999, Dewpoint 5*C, Q1021 in other words conditions are ideal. Suppose TORA = 2870m; TODA = 3330m; ASDA = 2900m [there is a small local shortening]. There are 174 passengers, 15 seats are empty. Each passenger weighs 80kg and the bags total is 18kg per person. The aircraft is a B737-800W in good condition so I am going to slide in some figures from my tablet. I won’t list them all. MTOW is 75210kg, OEW is 42990, MZFW 61680kg, MLW is 65310kg. I press the tablet keys and the fuel at take-off 9220kg with 6300kg block and 2920kg remaining. It’s a flaps 1, TO1 33* assumed temp departure from RW27, flight time 148~152 minutes no problems expected. The underload is estimated at 1600kg and is a start point to think about the tanker option. Airlines like to keep TOW costs low. Also the "invisible bowser" might have been a hydrant.

[Doors to Automatic]

Thanks for replies folks. Enicalyth - it was the return sector and you might wish to assume 3544m for the TORA