...well I'll just fill them up until it's running down the wings....
Fill your average C-172 or Cherokee like that, then load you and 3 of your friendly rugby team, pls baggage - and tell me how much runway you'd need to get airborne, or where the hole would be off the end for me to start digging for you, and if you did get airborne, and had some emergency that required you to return to the airfield pronto, like one of your mates suddenly had a heart attack, could you go around with full flap when some kid ran on to the runway just as you were about to flare ? Don't tell me it will never happen, Mr. Murphy is always with us.
I'm referring to operating a Cessna on Coastguard Search and Rescue at short notice. We can't leave the aircraft topped up in case the only crew who answer the pagers are the four heaviest of our team - and I can assure you that some are HEAVY !
We have to balance the length of time we can remain airborne to Search For Those In Peril On The Sea, against the length of runway we don't have available to take-off grossly overweight - even if we were prepared to.
We upgraded to a C-182 from a C-172 to give us more flexibility in this respect but still have weight/performance restraints, sometimes.
Course, if NZ Coastguard would give us a C-130 ..... ! ( and the money to fill the tanks ... )
Nb. On of our team relates to an experience in New Guinea operating a C-182. Filled to overflowing, one tank then started to syphon out of a cap that had not been properly secured, the base of the bladder tank rose to fill the space so that it continued syphoning out of the top and the fuel gauge probe still thought that there was petrol in the tank. Engine stopped. Trees. Jungle. ( Cannibals ? ) Mountains. Mist. He survived.
Mr. Murphy is always with us.
(Sorry, not trying to be rude, but you can't just say fill 'er up )