On November 14, 2009, approximately 1800 central standard time, an Airbus A319-111, N924FR, operated by Frontier Airlines as flight 820, struck a flock of birds shortly after taking off from runway 1R at Kansas City International Airport (MCI), Kansas City, Missouri. Visual meteorological conditions prevailed at the time of the incident. The scheduled domestic passenger flight was being conducted under the provisions of Title 14 Code of Federal Regulations (CFR) Part 121, and an IFR (flight rules) flight plan had been filed and activated. There were no injuries to the 5 crew members, 120 passengers, and 5 non-revenue passengers. The flight had just originated from MCI, and was en route to Denver International Airport (DEN), Denver, Colorado. The crew said they thought they had struck 6 or 7 geese. The event was captured at 0104:29 UTC (Universal Time Coordinated) on ACARS (Aircraft Communications Addressing and Reporting System) data as the airplane was climbing through 4,260 feet at 252 knots (see attachment to this report). The right engine spooled down to flight idle. When the crew attempted to advance the throttle, there were a series of compressor stalls. Passengers said they saw fireballs being ejected from the engine. The crew declared an emergency and returned to MCI. Inspection disclosed damage to both engine inlet cowlings, but boroscope examination revealed only the right engine, a General Electric CFM56-5B5P, had sustained internal damage. Bird remains were recovered from the right engine and sent to the Smithsonian Institute in Washington, DC. The remains were identified as Lesser Snow Goose (Chen caerulescens caerulescens). The average weight of the bird is 5.3 pounds. The number of birds ingested and the sex were not given (see letter attached to this report).