B777-200
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 122; Flight Crew Total 25000; Flight Crew Type 878
Situational Awareness
Deviation / Discrepancy - Procedural Published Material / Policy
General None Reported / Taken
Human Factors; Procedure
During flight planning; I checked the fuel remaining vs. fuel required at CP-1 on the ETOPS Analysis at the end of the Operational Flight Plan; noting only a 700 pound pad at CP-1. Upon reading the Critical Point diversion Profile and Time; I noted the critical fuel scenario was predicated on a diversion speed of 256 kias. This is inconsistent with both FOM; ECL; and FM guidance. (Flight Plan and ETOPS Analysis attached)FOM describes the ETOPS Analysis page of the OFP. Item 9 titled Fuel (Critical Fuel Component Breakdown) states 'Descent/CRZ FL100/Approach' and assumes an emergency descent and cruise at FL100 'at the approved single engine diversion speed....' FM ETOPS Flight lists the 777-200A single engine diversion speed at .84M/290 kias. FM and the aircraft electronic checklist list the recommended speed as 320 kias/.83M. Regardless of which speed is used; it is significantly higher than 256 knots for ETOPS considerations; with a higher fuel burn. Most notable of the ETOPS concerns is fire suppression. By using 256 kias diversion speed in calculating the fuel required at a Critical Point; the flight may not have adequate fuel to divert at the approved single engine diversion speed as specified in Flight Manual and FOM guidance. On this particular flight; utilizing the slower speed results in a 205 minute diversion time with no option to increase the diversion speed under the worst case scenario. If the procedural guidance in the FM; FOM; and ECL recommends a diversion speed of 320 or 290; the flight planning process needs to use that number to calculate the diversion fuel in the critical fuel scenario.
B777 Captain reported noticing a flight planning anomaly related to ETOPS fuel calculations.