I was out at Tullamarine this morning and because of the strong northerly winds, all aircraft were taking off on 34(?). I noticed that QF93 left the gate pretty much right on time (0920). It was taxiing behind about 9 other aircraft waiting to take off. It was about 50 mins by the time it left the gate until take off. My question is, how do you allow for this amount of fuel usage before take off? Are you informed by ATC about the delays when calculating fuel quantities?
We normally allow a tonne of fuel for the taxi, and that covers up to around 20 minutes. Beyond that it will start to eat into the variable fuel load, if you haven't allowed extra for the delay. Generally the company flight plan won't, but we'll often adjust it based on what we see of the conditions (we don't just sleep during the cab ride). Some places (JFK) were particularly bad for ground delays, and there the company will increase the planned fuel loading based upon previous flights. I think I once burnt about 8 tonnes waiting on the ground there, but it was all allowed for anyway. But, I have seen aircraft that have been delayed so long that they've had to go back to the gate.
Whilst on fuel flight plans, the company provides me with a minimum fuel flight plan. So, basically they're giving me information that would allow the minimum legal fuel carriage. The plan will often include adjustments that we can consider which use faster or slower cruise speeds, but they're just there so that I know the minimum I'd need with those cruise numbers. But, there is no requirement whatsoever for me to actually carry that minimum load...that's simply the line below which I can't go. Often, minimum is perfectly acceptable (generally when it includes something that's actually forced additional carriage anyway), but equally often I'll increase it by 1 to 5 tonnes. I think the largest amount I've ever added was 15 tonnes.
It is possible to put too much fuel on too. Maximum landing weight is generally not an issue, but if you were forced by weather or works to use a shorter than normal runway, you'd certainly want to have considered this when ordering the fuel. Also, that tonne that we normally allow for taxi won't actually be consumed in some cases (departing LA from 24L for instance) in which a short taxi combines with a short runway, and max take off weight. Then you'll have to load based on burning less (perhaps 500 kgs) and keep a very close eye on the actual weight before you start the takeoff.
And back to your original question. The A380 suffers very badly with congestion delays when Melbourne is on one runway. The gaps between the arriving aircraft are fairly close (and there are a lot of arriving aircraft). Whilst the smaller jets are quite nimble on the ground and a departure can often be squeezed between the arrivals, it takes a bit of time to actually get a 380 onto the runway and away.
