B767 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 210; Flight Crew Total 13000; Flight Crew Type 1300
Communication Breakdown; Situational Awareness
ATC Issue All Types; Inflight Event / Encounter Wake Vortex Encounter
Flight Crew Became Reoriented
Environment - Non Weather Related; Procedure
Approximately 9 miles behind a B747-400 both going to EHAM. ATC asked us to expedite descent (cleared to FL70) on our direct SPL. Aircraft on autopilot in Flight Level change. Speed 250 KIAS. We were not made aware of traffic category or type; but we had heard an aircraft told to speed up as we were told to slow down earlier and surmised that the target on TCAS was that traffic. I later figured out that it was a 747. We got a wake encounter at about FL94. Aircraft banked right about 15 degrees while control column was to left about 1/2 deflection. The roll was very uncoordinated (slip). I later saw on Flight Aware that our track changed by 3 degrees. The duration was about 10 seconds. The speed did vary but I did not see how much (aircraft was at flight idle). ATC didn't give us any 'caution wake' prior and we couldn't discern the word 'heavy' in any radio calls (either from ATC or the traffic). Language/accent may have been a factor. The native Dutch to Dutch transmissions; in English; are difficult to understand the call signs (might be radios). Probably was a minor wake upset; but could have been more severe if passengers hadn't been down earlier. Flight attendants did complain later; but no one was injured.
B767 First Officer reported encountering wake turbulence from a preceding B747 on arrival into EHAM.