True that big jets like the 747 cannot have both full payload and full fuel?

Question

I mean, the max. take off weight for the 747 ist about 400 tons.

The empty mass (without payload/fuel) is about 180 tons.

Max. fuel capacity is about 180 tons.

So, if you calculate the empty mass with max. fuel (180+180 tons), you have 360 tons. So, you can put around 40 tons of payload (because max. take off weight is 400 tons) in the plane. However, the plane is certified to have about 50 tons of payload (but you cannot put it fully in because otherwise you would be over 400 tons).

So, if airlines make long flights (like LAX-Hong Kong), what do they do? Do they sell less seats, so that they can put enough fuel for the trip?

Answer 1

they carefully calculate the fuel...also, the max take-off weight is different from the max landing weight!  i believe you can take off with more than you can land (with)....

Answer 2

passenger flights aren't usually bumping up that close to the max payload (unless they are carrying freight or something too). That is more an issue for the cargo hauling versions.

Though from what I've seen, 50 tons seems on the lighter side of the 747 payload capacities. The 747 can carry at least 300 lbs per passenger with a full load, (including the person and their luggage, the average would be significantly less weight than that per person).

Like the previous answer said, it's all a balancing act. Carrying more fuel also means the plane burns more fuel because it's heavier, so they usually don't put in too much extra (other than the extra needed for safety margins). EXCEPT, when they are flying to an airport where the fuel is much more expensive, they will often fly with a full load and just top off there to avoid buying all the gas at the higher price. (even airlines have strategies for saving gas money).

Answer 3

Maximum Payload implies that you have the max pax + max fuel load for a total maximum take off weight.  This is not the maximum fuel load capablility.

If you reduce the number of pax then then you can have a max fuel load.  Obviously, if you have no passengers and a max fuel load you then may have maximum range.  Its all a trade off between the three  (range, passengers/baggage, fuel)

Answer 4

Yep you got it. Don't know of an airliner that can fill all the tanks and all the seats and still go. Unless of course it doesn't have all the seats like our 727 executive aircraft. It only has sixteen seats so no worries. The other answers here will misslead you.

Answer 5

I was flying from LAX to Hong Kong on a 747 as a passenger, and the captain told us that we would have to stop in Seoul Korea to get more fuel.  We had too much of a passenger and baggage load, so we couldn't do the trip direct without a fuel stop.  I suppose he could have bumped passengers, but they decided to make a stop instead.  

Back when I flew an RJ, I once had a passenger ask me why we had to bump bags to make our takeoff weight.  I told him that most aircraft were unable to carry full fuel and a full load of pax and bags at the same time.  He said, "What about a 747?"  I told him it didn't matter, but I don't think he believed me.  That was before I took the flight with the fuel stop.

Answer 6

this is where the cargo clerk or what we called in airline terms (load controller) comes in and he must be correct in his calculations i.e. take off weight and center of gravity placement it has some allowances whether you go more fwd or more aft. The pilot can even maximize the 747 fuel load around 150,000. The pilot with the more than heavy load he  has he will compensate the long runway of the departure airport he is in.

Answer 7

Theoretically there are some extremely heavy loads that a 747 carries on rare occasions, like spare parts for earthmoving equiptment, so if you don't have far to go, don't fill the tanks and the plane will still be able to get off the ground, even if it would be too heavy carrying both that load and full tanks.

Make sure the tanks are empty when you try to land it

Answer 8

Most airliners can fill all the fuel capacity and all the seats and fly.  This is NOT the longest range arrangement, which would have less payload (heavier the airplane = more drag).  It's not full payload either- full payload is full passenger count PLUS full cargo (belly) capacity.  It's cargo that is sacrificed first because cargo pays less per pound per mile than passengers.

There is a range called the 'max payload range' which is with the fuel load available with full passengers and cargo; another for max passenger count, and no cargo; and an endurance range with whatever mass can be carried as payload with full fuel (matters for freighters).