Human-Machine Interface; Situational Awareness
Aircraft Equipment Problem Less Severe; Deviation - Altitude Crossing Restriction Not Met; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued New Clearance; Flight Crew Became Reoriented; Flight Crew Requested ATC Assistance / Clarification
Aircraft; Human Factors
We were on the Lam 12X departure from RWY 35R and cleared above 5000 meters prior PD062. We had a frequency change; checked for anti-ice requirements after entering IMC; and had just finished the after takeoff checklist. The crossing restriction of 4930 feet was entered and verified for HSH prior to departure. The aircraft had around 40k lbs fuel and less than 5k lbs freight and was very light. The climb rate was close to 10;000 FPM. We had not reached PD062 and as the airplane started to pitch down to level off; the HSH altitude restriction disappeared from FMS and aircraft continued to climb. Since the clearance and FCP was in meters; and the FMS and chart was in feet; it took me a few seconds to confirm exactly what happened and that we were in fact supposed to level off at 4930 until passing HSH. Since I had never seen an FMS altitude deletion like that I thought I might have made a mistake in meters/feet conversion; or had the waypoints confused. In addition; as this was happening; we were cleared direct to HSH. Due to the high climb rate; by the time I confirmed that we had climbed above a restriction; we were already significantly higher; and we immediately asked for an unrestricted climb; which was granted. No mention was made by ATC of missing an altitude restriction. All both crewmembers saw out of the corner of our eyes was a flash on the FMS (similar to a waypoint sequencing) when the restriction was removed; and neither of us was making an FMS entry at the time. One reason it took me a few seconds to confirm that we were above the restriction was that the airplane acted as if it was approaching an altitude restriction and the waypoint of the restriction simultaneously. It appeared that the flash was normal waypoint sequencing as the altitude restriction was met; and that it was just continuing the climb. Again; since I'd never seen an altitude restriction removed by the FMS at first I thought I might have confused which waypoint had the altitude restriction. It didn't take long to realize what happened and to confirm that I understood where we were; but with a 10;000 FPM climb rate; 15 seconds is a climb of 2500 feet. I've never seen the FMS remove a restriction like that; nor have I ever seen the MD-11 automation not honor an FMS entered crossing restriction without alerting the crew before that it wasn't possible. I am not sure why the FMS removed the restriction. I don't know if there is a software issue or something else caused the restriction to be removed. The high climb rate may have been an issue. Obviously; better pilot monitoring of the situation could have prevented the event; but in some ways this was similar to taking controls from another pilot during a botched landing. There was only a small window when intervention was possible to prevent the deviation. The MD-11 can sometimes wait until the last second to make pitch changes when leveling off. Since we were climbing at 10;000 FPM and the plane just starting to pitch for level off; I assumed it would make the programmed restriction. In addition; there was a few seconds of confusion in my mind regarding meters/feet conversion. I think the cleared altitude was around 5500 meters which was numerically close to the altitude restriction in feet and it took a few seconds to ensure I understood the aircraft altitude in relation to both the cleared altitude and the crossing restriction. Normally a few seconds is not a factor; but when climbing at 10;000 FPM it is a significant altitude gain. Given our current procedures of mixing feet and meters in our operations; the best way to handle a ZSPD departure is for the pilot flying to focus only on the course and altitude and not get distracted backing up the pilot monitoring on radio; anti-ice; and FMS usage. This is less than ideal as both pilots need backup in a busy foreign environment. Either chart and operate in meters or feet. Using charts in feet and accepting clearances in meters can lead toconfusion. It is not a difficult conversion; but after takeoff with several other issues requiring attention; taking a few seconds to confirm altitude awareness can be critical.
MD11 Captain reports missing a crossing restriction at HSH during the LAM 12X departure from ZSPD. The aircraft was climbing at more than 10;000 FPM and was given direct HSH as the aircraft was starting to level off at 4;930 feet. For some reason the FMC deleted the HSH crossing restriction at that time and continued climbing.