Flight planning - computer flight plans and operational flight plan
Flight planning - computer flight plans and operational flight plan tests your ability to read a computed OFP and check it against the route, weather and fuel policy. It covers the nav log, winds, temperatures, Mach and cost index, fuel breakdown, alternates and actual time over.
OFP content
- The nav log shows route, waypoints, track, distance, wind, ground speed, time, fuel flow and fuel remaining.
- Cost index trades time against fuel; a higher CI generally increases speed and burn.
- The operational flight plan includes fuel figures, alternates, equal-time points, ATO and performance data.
- The ATC flight plan is not the same document as the OFP.
Worked example
A leg is 1,200 NM with ground speed 450 kt. Time = 1,200 ÷ 450 = 2.667 h, or 2 h 40 min. At 2,500 kg/h fuel flow, fuel = 2.667 × 2,500 = 6,667 kg. If the OFP shows 7,000 kg, the 333 kg difference is about 8 minutes at that flow; check whether the OFP included a different wind, taxi fuel or a different cost index.
Traps
Do not read Zulu times as local time. Fuel remaining is not the same as endurance. Do not keep using planned ground speed after a wind update. Check whether taxi fuel is included in the total you are comparing.