EASA guidance material:
GM1 CAT.OP.MPA.150(c)(3)(i) fFUEL POLICY Factors that may influence fuel required on a particular flight in an unpredictable way include deviations of an individual aeroplane from the expected fuel consumption data, deviations from forecast meteorological condi- tions and deviations from planned routings and/or cruising levels/altitudes.