B777 Undifferentiated or Other Model
Flight Crew Last 90 Days 240; Flight Crew Total 23735; Flight Crew Type 6500
Human-Machine Interface; Situational Awareness
Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued New Clearance; Flight Crew Became Reoriented
Human Factors
Cruising at FL360 we were cleared to FL310 while 10 NM north of GRB and requested to expedite. Subsequently cleared to FL280 while still in VNAV. MCP altitude window was reset to FL280 but button was not pushed. Aircraft leveled at FL310 while remaining in VNAV. Told by ATC to turn to 090 HDG and continue descent to FL280. Received TCAS traffic caution about this time from opposite direction aircraft at FL300. Next told by ATC to maintain FL310. We climbed from about FL307 to FL310. First Officer disconnected autopilot and started turn to 090 and climbed back up to FL310.
B777 First Officer reports being cleared to FL310 and initiating descent in VNAV. He is subsequently cleared to FL280 which is set in the MCP but the button is not pushed and the aircraft levels off at FL310. This is not immediately detected by ATC or the crew resulting in a conflict.