Abstract
Temperature rise during climb-out at an inversion layer can cause a loss of thrust. When calculating take-off performance, the highest temperature in the inversion layer should be considered. IFALPA suggests revising ICAO Annex 6, para. 5.2.6 to include ambient temperature aloft and on the ground as part of the factors that significantly affect aircraft performance, directly or indirectly through allowances or margins provided in performance data or operational codes.