B767-300 and 300 ER
Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Flight Crew Total 15000
Aircraft Equipment Problem Critical
Flight Crew Diverted; Flight Crew Landed As Precaution; General Maintenance Action
Aircraft
Approximately 50 minutes after departure at FL360 we heard a loud bang and the aircraft shuddered. We looked at all the EICAS (Engine Indicating and Crew Alerting System) screens and they appeared normal. We were just handed off to ATC. The Captain then noticed the all the left engine parameters were fluctuating.Somewhere around this time we got a call from the back letting us know about what they heard and felt. The FA's (flight attendants) were concerned as well as passengers. We discussed the situation and decided to get Dispatch involved. I call the back to get the relief pilot back to the cockpit.We all decided that we should divert to [a nearby alternate] as a precaution. I told ATC that we would like to turn around and land. They cleared us back via a left turn. We landed without incident approximately 6;300 lbs over weight.
B767 First Officer reported diverting to an alternate airport after experiencing left engine anomalies; including a possible compressor stall.