Narrative:

After takeoff; a flock of birds was encountered at approximately 1;000 feet-1;100 feet AGL. The conditions were dark VFR. I first officer (first officer) was the pilot flying. Concurrently with the 1;000 feet call; I noticed a flock of white birds at the 12 o'clock position. There was no way to avoid the flock and we flew through it at approximately 170 knots with flaps 1 in takeoff power. The set speed call had already been made at this time and we were beginning to accelerate to the up bug speed. The left engine began surging and we reduced the power on the engine and it showed normal indications. I continued to fly the aircraft and the captain made the call to ATC to let them know our situation with the intent to return to the airport. I flew a left downwind at 3;000 feet MSL while the captain talked to the cabin crew and the passengers. We then began to run the appropriate checklists from the QRH. We flew an uneventful visual approach backed up. The landing was made at approximately 124;000 pounds. Airport fire/rescue was standing by as we landed; but we did not need their services. All aircraft systems performed normally during the approach; landing; and taxi phases except for the reduced thrust from the left engine. When we returned to the gate I performed a walkaround and noted damaged fan blades on the left engine and noted some bird remains (blood/feathers) inside; outside; and on the lip of the right engine.; and on the lip of the right engine.

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Original NASA ASRS Text

Title: At about 1;000 feet after departure; a B737-700 encountered a bird flock which caused left engine surging. The aircraft returned to the departure airport where severe left engine damage was discovered as well as bird remains in the functioning right engine.

Narrative: After takeoff; a flock of birds was encountered at approximately 1;000 feet-1;100 feet AGL. The conditions were dark VFR. I First Officer (FO) was the Pilot Flying. Concurrently with the 1;000 feet call; I noticed a flock of white birds at the 12 o'clock position. There was no way to avoid the flock and we flew through it at approximately 170 knots with flaps 1 in takeoff power. The set speed call had already been made at this time and we were beginning to accelerate to the up bug speed. The left engine began surging and we reduced the power on the engine and it showed normal indications. I continued to fly the aircraft and the Captain made the call to ATC to let them know our situation with the intent to return to the airport. I flew a left downwind at 3;000 feet MSL while the Captain talked to the Cabin Crew and the Passengers. We then began to run the appropriate checklists from the QRH. We flew an uneventful visual approach backed up. The landing was made at approximately 124;000 pounds. Airport Fire/Rescue was standing by as we landed; but we did not need their services. All aircraft systems performed normally during the approach; landing; and taxi phases except for the reduced thrust from the left engine. When we returned to the gate I performed a walkaround and noted damaged fan blades on the left engine and noted some bird remains (blood/feathers) inside; outside; and on the lip of the right engine.; and on the lip of the right engine.

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.