How is mission fuel requirement calculated?

Mission fuel calculated by integrating fuel flow along mission profile. Segments: Taxi and takeoff - Ground operations, takeoff fuel; Climb - Fuel to cruise altitude, distance covered; Cruise - Breguet range equation, step climbs for efficiency; Descent - Usually negligible fuel credit; Approach and landing - Fuel to landing; and Reserves - FAR (45 min hold), NBAA IFR (alternate + 45 min), or policy. Calculation: Break mission into segments, Calculate segment fuel from SFC, thrust, time, and Sum to get block fuel. Cruise fuel: F = Wi * [1 - exp(-R*SFC/(V*L/D))], where R is range, V is speed. Analysis: Specific Air Range (SAR) = V*L/D / (SFC*W) for cruise efficiency; Optimal altitude increases as weight decreases (step climb). Fuel planning: Block fuel + taxi fuel + reserve, Weight iteration (fuel affects weight affects fuel). Fuel efficiency metrics: Block fuel per seat-mile, critical competitive parameter.