Hi mathy,
Not 352 tonnes – well below that for this route. The passenger load is much less than some would expect. I've seen a few people do these analyses based on maximum passenger capacity which for the 777 can be anything from 305 to 550 pax. In service though, the airline seat fit can be much less than this, and my pax numbers are based on an actual airline and they are fitted for below 300 in a 3 class layout. And the cargo load is low for this route. And the fuel load is quite a bit less than maximum. It all adds up, and this operation is planned at some 50 tonnes lighter than MTOW.
For me, looking at the runway, it makes quite a difference. There is something in this which is a lesson to airport engineers and perhaps some pilots as well. Forgive me if I speak in simple terms – I am used to explaining this to governments and airports and they need it being kept simple. In the old days, inter-continental operations meant long runways – 3500m was a typical figure, and more if the runway was at elevation or in a hot place. Johannesburg is up to 4390m long. I took a look at a runway last week for another very high and warmish country, and the first pass come out at 5000 metres which is too long for the tyre temperature limits. I have a simplistic rule of thumb that tyres tend to blow at about 4500m on the takeoff run – not scientific but it alerts me to check it properly if I am close.
The outstanding performance of the modern twins has changed some of the rules of the game in terms of runway length. The aircraft that go an ultra-long distance need a lot of fuel just to be able to carry ALL the fuel required for the flight. The engines are massively up-sized so they can haul the whole lot off the ground on just one engine. When those aircraft operate on a somewhat shorter route, then the drop in fuel load needed is significant but the massive engines are still there. The takeoff performance is nothing short of astonishing (without de-rate), and inter-continental operations can easily take place off short 2500m or 2700m runways.
Cheers
Overrun
PS - and I share Mutt's confidence in the figures