Good post, and spoken with far more confidence and assurance in the subject than I!
In addition, you hear stories of some more stingy airlines who fuel up to the absolute minimum they can get away with too, to ensure their aircraft is as light as possible. I guess at some point there will be international safety laws that ensure aircraft are fuelled sufficiently at all times, but I guess there will be some that push it as close to the wire as they can get away with.
All UK airlines have to be stingy, because fuel costs are astronomically high compared to other operating costs. The amount of fuel is carefully calculated and legally required.
The flight plan will tell you how much fuel you need which, in basic terms, will be this as a minimum:
- Fuel to taxi to the departure runway
- Fuel to fly to destination
- 30 minutes holding fuel
- Fuel to get to alternate
You’re not legally obliged to take any extra and there is a 3 or 5% contingency built into the figure which covers most eventualities such as not getting the cruise level you expect etc.
Most UK airlines will ask the commander to justify taking any fuel above this amount. Different airlines have subtlety different attitudes to taking extra fuel, but there is rarely anything beyond a gentle pressure to not take more than you need.
The usual reasons for taking extra would be forecast bad weather (enroute or at destination) or experience of delays (you’ll always hold on your way into a busy airport such as Heathrow).
In reality, if you took the minimum fuel as calculated by the flight plan every day, you’d be fine 99% of the time, so there’s no suggestion that taking minimum fuel marks you out as some sort of cowboy. The 1% (actually less) when this fuel isn’t enough will result in a diversion and associated costs, but this cost is lower than taking extra fuel on every flight and therefore adding unnecessary weight to the aircraft which, in turn, means the fuel burn is higher. Everything relates to the cost of fuel.
The rare exception is fuel tankering, where you take as much as you can fit/need, restricted by the maximum takeoff or landing weight of the aircraft or, in extreme cases, the maximum amount of fuel you can fit in the tanks. The cost of fuel tankering is calculated for every flight and reflects the price of fuel in each airport. If, for example, you’re going from Gatwick to Nice and back, the fuel prices at each airport will be looked at to work out whether it’s worth carrying extra. If you needed 5000kgs of fuel to get to Nice and 5000kgs to get back, it’d be worked out whether it’s actually cheaper to just load up 10000kgs in Gatwick and carry the extra to Nice so that you don’t need to buy your fuel there at higher cost. It’s a questionable practice because, whilst it saves money, it unnecessarily burns fuel so doesn’t fit too well with the industry’s green credentials...