Narrative:

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.

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Original NASA ASRS Text

Title: B777 Captain reported noticing a flight planning anomaly related to ETOPS fuel calculations.

Narrative: 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.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.