B777 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 175; Flight Crew Total 18410; Flight Crew Type 3124
Aircraft Equipment Problem Less Severe; Deviation - Speed All Types; Deviation / Discrepancy - Procedural MEL / CDL; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Became Reoriented
MEL; Company Policy; Human Factors
Our flight was dispatched with MEL 32060 (main gear uplock spring missing). Though flight can be flown with gear up; MEL restricts it to max gear extend speed of 270/.82. Feeling the flight plan needed to better account for this restriction the Captain was on the phone with dispatch for quite some time going over scenarios and safety issues associated with this limitation. While this was going on we agreed that the FO and I would head to the airplane to run preflight and setup checks. 10;000 lbs of fuel was added at Captains request per our situation in regards to the MEL issue. Halfway into the flight the other IRO and myself entered the cockpit; at the completion of our rest period; and shortly after we began discussing the speed restriction as it pertains to anything that we might have overlooked. We then sent a message to dispatch about our concern that if we had to divert from a critical point to an alternate the planned divert speed would be limited to 270 and had that been accounted for? Apparently it was not and we were told this info would be passed on to the Sabre people. We asked for a follow up response if it were possible for them. Though we didn't hear back before conclusion of flight. The FOM does say Sabre takes into account MEL and performance adjustments for weight and speed; though it didn't in our case. We could have used better VVM earlier on in digging deeper into being sure we accounted for all the issues the MEL would affect.
Flight operated with MEL 3232D. The MEL was for a missing main gear up lock spring and required that the entire flight be operated at or below the maximum gear speed of 270KTS/.82M. My assumption for the restriction is that it protects against unanticipated gear deployment on the affected side. I also assume that while such a threat is remote; there would seem to be at least a more elevated risk of such an event occurring or else the MEL would not include the speed restriction. During the early preflight planning stage the Captain phoned dispatch to inquire what our fuel burn might look like if the gear were to partially deploy at ETOPS CPS. I believe the Captain also inquired as to the point at which the gear might be able to deploy and the a/c would be able to continue on. Such questions seem reasonable to me. In the event that our gear drops while operating on a 180 ETOPS over Polar Oceanic airspace with MEL 3232D what might the burn look like with respect to the critical points. Getting any sort of even a ballpark figure seemed very difficult. What was missed by all during this discussion was that our ETOPS times/distances were figured using a speed of 329KTS. This was in violation of what the MEL required. I'm not sure if this means that the flight failed to comply the required 180 ETOPS rules. The error was noticed in the vicinity of our final CP and a message was sent to dispatch at that time.My understanding of SABRE is that it will account for MEL restrictions. With respect to ETOPS calculations SABRE does not appear to account for MELs. Another issue with the SABRE flight plan is that while it never showed a speed above .82M; it did not seem to be able to determine where in the flight the speed would transition from KIAS to M. The flight plan showed .82M at the initial FL280 cruise altitude. At FL280 and approximately 610lbs we were 270KIAS/.69M. The actual transition to .82M did not occur until about 9 hours into the flight. Prior to that point the a/c was limited to 270KIAS. The fuel burn for the flight was mostly accurate with SABRE calculations; but the flight time was off by 30+ minutes. Is it possible for SABRE to compute a cruise speed in both KIAS and M for different parts of a flight? Another potential area of concern with the 270KIAS/.82M restriction for such a long haul flight is for turbulence. The turbulence forecast along our route was good; but having the MEL speed restriction meant that we would be operating below the recommended severe turbulence penetration speed for the first 9 hours of our flight. Much of that time would also be spent in remote ETOPS Polar airspace. Any type of encounter with significant turbulence would create issues that the MEL and SABRE may not be accounting for. At the initial cruise altitude of FL280 the 270KIAS was only about 10KIAS above the start of the yellow band. This is not the most comfortable spot to be cruising around at while at such a heavy weight. Does SABRE and Dispatch consider turbulence penetration speeds while flight planning with the MEL restriction? Should some amount of ADD fuel be required for such contingicies?Finally; with respect to MEL 3232D; is there any extra consideration with respect to terrain and partial gear deployment? Polar flights often cruise over parts of Greenland during the initial hours while still at very heavy weights. While very remote; what might gear deployment look like over Greenland while operating with the MEL? If the risk for such an occurrence is no greater than during a regular flight then why does the MEL restrict our speed for the duration of the flight? A little more help in the preflight stage would have been appreciated and might have given the crew a better understanding of the best option available in the event of any unplanned inflight issues. There are times during Polar ops were you are mostly on your own and the ability to communicate with dispatch in a timely manner is not even remotely possible.
B777 flight crew reported being dispatched with a MEL restricting airspeed to 270 knots or Mach .82. They felt that the computer flight plan did not reflect these limitations in its calculations.