B767-300 and 300 ER
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Situational Awareness
Deviation - Speed All Types; Inflight Event / Encounter Wake Vortex Encounter
Flight Crew Became Reoriented; Flight Crew Took Evasive Action
Environment - Non Weather Related; Human Factors; Procedure
Departing RJAA. I was PF (Pilot Flying). Captain was PM (Pilot Monitoring). Relief FO (First Officer) was sitting in observer seat. We were within a close margin of max structural weight but within all limits. It was briefed that the best angle speed (258 kts.) and flaps up maneuver speed (254 kts.) would exceed the 250 [kts.] below 10;000 ft. restriction so we opted to keep Flaps 1 until passing 10;000 [ft.] so that we could maintain maneuverability. Once we cleaned up to Flaps 1; I opened the speed window and manually set speed to 240 kts. The overspeed margin was currently 250 kts. The underspeed margin was around 225 kts. Flaps 1 maneuver speed was about 235 kts. Upon reaching 10;000 ft.; I put 245 kts. in the speed window to initiate an acceleration that would then continue past 254 kts. for the Flaps Up speed as the flaps transitioned. The transition was going as planned until we hit some moderate wake turbulence from crossing traffic. The speed started to shoot up dramatically towards the upper limit. I applied some back pressure while keeping the AP engaged to get the nose up and arrest the speed increase. I was able to arrest most of the speed increase but it still resulted in a 1 or 2 kt. overspeed. At this time; the turbulence became more intense and both the low and high speed regimes converged. I disengaged the AP/AT (Autopilot/Autothrottle) and hand flew to best maintain airspeed as I anticipated a drop in airspeed on the other side of the wake turbulence. The airspeed started to drop but was arrested with manual input. Once the high and low speed margins stabilized and the turbulence subsided; we re-automated the aircraft and continued our departure without incident.I did not anticipate the wake of crossing traffic to be such a factor in our tight tolerances. When so close to max structural weight on TO (takeoff); the transition from Flaps 1 to Flaps Up is always on a razor thin margin. Any significant wake; turbulence or even wind shift will put you into and undesired airspeed regime. I would suggest not loading the aircraft right up to max weights and this has always been an issue for flap transition on the 767.
B767 F/O reported encountering wake turbulence departing RJAA at a heavy weight that resulted in an airspeed deviation.