B767-300 and 300 ER
Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Engineer; Flight Crew Instrument
Flight Crew Last 90 Days 189; Flight Crew Total 26000; Flight Crew Type 8200
Situational Awareness; Fatigue
Deviation - Altitude Crossing Restriction Not Met; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter Wake Vortex Encounter
Air Traffic Control Issued New Clearance; Flight Crew Became Reoriented
Environment - Non Weather Related; Human Factors
[We were] operating out of RKSI (Seoul/Incheon). ATC clearance received: 'ENKAS 1G departure; maintain FL290; Squawk XXXX'. [We] departed Runway 33L behind heavy Airbus. At 400 FT AGL 'LNAV' was selected. At 1;000 FT AGL 'VNAV' selected and flaps retracted to 5; autopilot engaged. At approximately 1;800 FT MSL encountered heavy wake turbulence from preceding Airbus; aircraft rolled quickly 20 degrees left. At this point I selected Flight Lever Change to maintain present speed and increase climb rate to climb above the wake turbulence. Continued this climb rate until above 5;000 FT MSL where a more normal climb rate was established. At 6;500 MSL Seoul Departure advised level off at 7;000 MSL; we leveled at 7;000 MSL and reported level to ATC. I than realized we had climbed above the 5;500 MSL altitude restriction required by waypoint (S1752) that was still 4 miles in front of us. We maintained 7;000 MSL for several minutes and than were re-cleared to FL290. The problem was caused when I selected Flight Level Change; this took us out of 'VNAV' and we lost the vertical protection the flight guidance system would have given us. To prevent this recurrence; the practice of setting the altitude restriction in the MCP instead of the 'cleared to' FL would have prevented this from happening when operating in either 'Level Change' or 'VNAV'. Factors Human Performance: Operating at 0130 per body clock.
SID states that aircraft violating DMZ will be shot down. At around 2;000 FT we encountered strong wake turbulence from preceding heavy Airbus. As I was concentrating on our critical ground track I failed to notice that Captain selected FL change to climb through turbulence at a higher rate. This removed our VNAV altitude protection and we climbed through the 5;500 FT restriction. Passing through approximately 6;500 FT Departure advised us to stop climb and level at 7;000 FT; which we did. We were subsequently cleared to resume our climb unrestricted to FL290.The lesson learned here is that 5;500 FT should have been set in our altitude alerter. This would have prevented us from relying solely on VNAV protection. FL290 could then have been set after we passed the restrictive waypoint.Human factors include general fatigue and jet lag from an extended period of international flying; and fear of violating North Korean airspace.
B767-300 flight crew reported deviating from charted departure procedure at RKSI when they encountered wake turbulence in trail of heavy Airbus.