Narrative:

Boarding; pushback and taxi out to runway were all uneventful. We were cleared for takeoff on runway xy. I was the pilot flying and the captain was the pilot monitoring. Shortly after gear retraction; the captain said 'bird'! As I looked up; I saw a large dark gray bird disappear under the nose. Moments later; there was a loud thump and the number 1 engine vibration gauge began to rise rapidly; while at the same time a vibration was felt and heard by both of us; as well as a strong burning flesh odor coming from the vents. I began to pull the number 1 throttle toward idle.as the engine N1 was reduced to 30 to 40 percent; the vibration stopped. We continued to climb and cleaned the aircraft up at 1000 feet AGL. When the captain checked in with departure control; he explained that we had ingested a bird and needed to level off around 5000 feet and would need some vectors to complete some items. The departure controller gave us vectors to the north and gave us instructions to level off at 6000 feet. We decided to keep the number 1 engine running near idle; as this took away all the vibration and allowed us to keep the services that the engine was still providing (hydraulics; electrics; etc). I took over ATC communications while the captain made a PA; talked to the flight attendants and to maintenance; who he asked to relay our situation to dispatch. He ran the numbers in the optimum performance capable (opc) and determined we would be landing overweight. I suggested because of our overweight status in an -800 [that we use] the longest runway available. The captain advised ATC of our runway request and told them we were ready for vectors back to the airport. Approximately ten miles from the airport; the captain took over as the pilot flying. The approach and landing were smooth and uneventful. We cleared the runway and the fire trucks followed us to the gate; with no indications of fire or fluids leaking.

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Original NASA ASRS Text

Title: B737-800 First Officer reported returning to departure airport after experiencing increased vibration associated with ingesting a large bird into #1 engine.

Narrative: Boarding; pushback and taxi out to runway were all uneventful. We were cleared for takeoff on Runway XY. I was the Pilot Flying and the Captain was the Pilot Monitoring. Shortly after gear retraction; the Captain said 'bird'! As I looked up; I saw a large dark gray bird disappear under the nose. Moments later; there was a loud thump and the number 1 engine vibration gauge began to rise rapidly; while at the same time a vibration was felt and heard by both of us; as well as a strong burning flesh odor coming from the vents. I began to pull the number 1 throttle toward idle.As the engine N1 was reduced to 30 to 40 percent; the vibration stopped. We continued to climb and cleaned the aircraft up at 1000 feet AGL. When the Captain checked in with Departure Control; he explained that we had ingested a bird and needed to level off around 5000 feet and would need some vectors to complete some items. The Departure Controller gave us vectors to the north and gave us instructions to level off at 6000 feet. We decided to keep the number 1 engine running near idle; as this took away all the vibration and allowed us to keep the services that the engine was still providing (hydraulics; electrics; etc). I took over ATC communications while the Captain made a PA; talked to the Flight Attendants and to Maintenance; who he asked to relay our situation to Dispatch. He ran the numbers in the Optimum Performance Capable (OPC) and determined we would be landing overweight. I suggested because of our overweight status in an -800 [that we use] the longest runway available. The Captain advised ATC of our runway request and told them we were ready for vectors back to the airport. Approximately ten miles from the airport; the Captain took over as the Pilot Flying. The approach and landing were smooth and uneventful. We cleared the runway and the fire trucks followed us to the gate; with no indications of fire or fluids leaking.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.