NTSB Factual Report

On February 18, 2008, at 1430 central standard time, a McDonnell Douglas MD-88, N935DL, operating as Delta Air Lines flight 1877, sustained minor damage when it struck a large bird while on a visual approach to Runway 35R at Austin Bergstrom International Airport (AUS), Austin, Texas. None of the 5 crew members or 135 passengers were injured. A instrument flight rules flight plan was filed for the flight that departed Hartsfield-Jackson Atlanta International Airport (ATL), Atlanta, Georgia, at 1311, and was destined for Austin. Visual meteorological conditions prevailed for the schedule passenger flight conducted under 14 Code of Federal Regulations Part 121.

The captain and first officer provided similar accounts of the incident. According to the captain's statements, the airplane was at an altitude of 1,800 feet above ground level (agl), approximately 4 to 5 miles from the airport, and at an airspeed of 210 knots, when he and the first officer saw two large birds in front of the airplane. Moments later one of the birds struck the bottom right side of the radome. The impact resulted in airframe vibrations; however, both engine indications remained normal. The first officer then declared an emergency and the captain informed the passengers about what had happened since it was "obvious we had collided with something." The airplane landed uneventfully, and once clear of the runway, the captain asked the airport's rescue and fire fighting (ARFF) personnel to assess the damage. They reported the impact area was "quite large with the bird imbedded into the radome."

Federal Aviation Administration (FAA) safety inspectors performed an on-scene examination of the airplane. According to an inspector, the bird struck the lower right hand corner of the radome (as viewed from the cockpit). As a result, the glide slope antenna mount, the lower nose-web, and outer fuselage skin was damaged. In addition, the forward bulkhead (non-pressurized) fuselage rib was torn. Blood was also observed on the right engine's nacelle; however, an inspection of the first and second stage blades revealed no damage.

Austin airport operations personnel sent photographs and feathers of the deceased bird to the Feather Identification Laboratory at the Smithsonian Institution, Museum of Natural History, who identified the bird as a Black Vulture. Airport operations personnel also produced several Airport Noise and Operations Monitoring System (ANOMS) plots, which showed that when the airplane was at a 1,800 agl, it was approximately 9 miles from the airport.

A review of Federal Aviation Regulation (FAR) 139.337(a), titled Wildlife Hazard Management, revealed that a certificate holder is required to conduct an ecological study (Wildlife Hazard Assessment) if an air carrier aircraft experiences a multiple bird strike, an engine ingestion, or a damaging collision with wildlife other than birds. Part 139 also requires that an assessment be conducted if wildlife of a size or in numbers capable of causing one of these events is observed to have access to any airport flight pattern or movement area.

According to a representative of Austin Airport, he said the airport "...does not have an FAA approved Wildlife Management Plan. To date there have been no incidents here at [AUS] that fits the criteria set aside by FAR 139.337(a) or [Advisory Circular 150/5200-33B, titled Hazardous Wildlife Attractants on or Near Airports] requiring such a plan."

NTSB Probable Cause

The airplane struck a large bird while making a visual approach to the airport.