Operationally, carrying of fuel in two tanks, one each fore and aft of the cockpit; and a ventral fuselage tank beneath, the Me 262 would have a total flight endurance of 60 to 90 minutes. Fuel was usually J2 (derived from brown coal), with the option of diesel or a mixture of oil and high octane B4 aviation petrol. Fuel consumption was double the rate of typical twin-engine fighter aircraft of the era, which led to the installation of a low-fuel warning indicator in the cockpit that notified pilots when remaining fuel fell below .