The aircraft used reheat (afterburners) only at take-off and to pass through the upper transonic regime to supersonic speeds, between Mach 0.95 and 1.7. Reheat was switched off at all other times.[99] Due to jet engines being highly inefficient at low speeds, Concorde burned two tonnes (4,400 lb) of fuel (almost 2% of the maximum fuel load) taxiing to the runway.[100] Fuel used is Jet A-1. Due to the high thrust produced even with the engines at idle, only the two outer engines were run after landing for easier taxiing and less brake pad wear – at low weights after landing, the aircraft would not remain stationary with all four engines idling requiring the brakes to be continuously applied to prevent the aircraft from rolling.