Date: 201511
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Flight conditions: Mixed
Weather elements / visibility: 10
Light: Night
Aircraft: B737 Next Generation Undifferentiated
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Climb
Airspace: Class E ZZZ
ATC / advisory: TRACON ZZZ
Reporter organization: Air Carrier
Reporter function: Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Second reporter function: Pilot Not Flying; First Officer
Anomaly: Aircraft Equipment Problem Critical; Inflight Event / Encounter Bird / Animal
Detector: Person Flight Crew
When detected: In-flight
Result: Aircraft Aircraft Damaged; Flight Crew Landed in Emergency Condition; Flight Crew Returned To Departure Airport
Contributing factors: Environment - Non Weather Related
Primary problem: Environment - Non Weather Related

Narrative: After takeoff climbing through approximately 2000 feet AGL; flew through flock of large birds; type unknown; and experienced multiple impacts. Immediately had indications of engine damage with RT ENG vibration meter over 5.0 and smell of burning feathers/flesh. Retarded RT ENG thrust lever to idle and indications returned to normal. [Advised ATC]; turned to downwind; and leveled off at 8000 feet MSL; approximately 200 feet below overcast. Started with Excessive Vibration Checklist; but then switched to Engine Severe Damage Checklist. Due to fact that RT ENG indications had stabilized and that multiple impacts had been detected; elected to continue to operate RT ENG in case LF ENG developed problems as flight continued. Then executed One Engine Inoperative Checklist; coordinated with ATC for return to runway; coordinated with Company Ops; briefed Flight Attendants and Passengers; and briefed approach as flew to 15-mile downwind and turned base to return to field. Made uneventful landing; had CFR [Crash Fire Rescue] check out aircraft; and taxied to gate. Elected to continue to operate RT ENG due to normal indications and less than good braking conditions. On post-flight extensive damage to RT ENG noted as well as spray of blood and feathers throughout inlet.This would be a great discussion item to use for sim briefs; a dynamic time-sensitive problem with unknown possible complications.


Second narrative: Shortly after takeoff the aircraft impacted a flock of multiple birds. The aircraft was climbing through 8000 feet at the time of impact. The bird strike resulted in the vibration meter for the right engine to be pegged at 5.0. Shortly thereafter; we experience a burning smell. No other abnormal indications were noted from inside the flightdeck.We immediately [advised ATC]; descended back to 8000 feet to remain in VMC conditions; and turned left to enter a left downwind. We initially started the Engine High Vibration QRH; then changed it to the Engine Severe Damage QRH. At this point; the right engine was at idle; there was no vibration noted; and the burning smell had disappeared. Because the Pilot Flying had visually seen the large flock of birds; we decided not to shut down the engine for fear that we may have had damage to the left engine as well. We both felt comfortable keeping the right engine at idle since it seemed to be operating normally.We decided to return to the field expeditiously; briefed the approach and completed the Single Engine Approach QRH. The aircraft landed and came to a complete stop. We had personnel inspect the aircraft. They did not see any damage and we taxied the aircraft to the gate. We continued to leave the Number 2 engine running due to the icy conditions on taxiways and ramp.


Synopsis: B737 flight crew reported returning to departure airport after a bird flock encounter in initial climb caused extensive damage to the right engine.