Overview
On February 1, 2013, at 0805 central standard time, a Cirrus SR22 (N247RB) and a Cessna 152 (N93124) collided in flight approximately 13 miles west-southwest of Easterwood Field Airport (CLL) in College Station, Texas. Both airplanes subsequently landed at CLL. The Cirrus SR22, operated as a demonstration airplane by Cirrus Aircraft Corporation, sustained substantial damage to the upper cockpit fuselage, and the commercial pilot suffered minor injuries. The Cessna 152, owned and operated by the Texas A&M Flying Club, sustained minor damage to the right main landing gear assembly; the flight instructor and the student pilot were not injured.
Pilot Accounts
The Cirrus pilot reported that after climbing above the departure airport's traffic pattern altitude, he engaged the autopilot and proceeded direct to CLL at 3,500 feet mean sea level (msl). As the flight neared CLL, the windshield suddenly imploded from an apparent impact with an object. He initially suspected a bird strike, having received no traffic advisories and not seeing another aircraft. He recovered from an unintended descent, continued toward CLL, and declared an emergency with the tower controller, though he had not established radio contact before the collision. He landed normally on runway 16.
The Cessna flight instructor stated that he was conducting a local training flight with a primary student on her second instructional flight, performing basic attitude maneuvers. While climbing to 3,500 feet msl on a southeast heading, they felt an impact and heard a loud bang from the right side aft of the main cabin. No flight control issues arose. The student observed another airplane in a rapid descent at their 10 o'clock position. The instructor entered a descending left turn to follow and heard an emergency declaration on the tower frequency. He turned toward CLL and informed the tower they had hit something. After the other aircraft landed, the tower advised that it had tire marks on its roof and requested a low approach to check the Cessna's landing gear. The instructor found that the right main landing gear wheel had separated; the student confirmed the left gear appeared undamaged. They performed a low pass, circled until emergency equipment was in position, and landed uneventfully on runway 22.
Flight Path Analysis
Global positioning system (GPS) data from both aircraft were analyzed. The Cirrus maintained a true course of 080 degrees at 3,500 feet msl for about 14 minutes before the collision. The Cessna, after departing CLL, conducted maneuvers consistent with flight instruction. About 90 seconds before impact, it was in a climbing left turn from west-southwest to south-southeast. During the 70 seconds before the collision, the Cessna held a 160-degree true course, climbing from 3,100 feet to a maximum GPS altitude of 3,573 feet about 12 seconds before impact, then descending approximately 60 feet at a rate of about 300 feet per minute. The collision occurred at 0805:47 at 3,500 feet msl. The angle between the flight paths was about 80 degrees. The average relative position of the Cessna to the Cirrus was 27 degrees left (11 o'clock), while the Cirrus was 72 degrees right of the Cessna (between 2 and 3 o'clock).
Traffic Advisory and Transponder Status
The Cirrus was equipped with a Garmin GTS 800 traffic advisory system, which interrogates aircraft transponders to provide traffic alerts. The system only displays targets from aircraft with responsive transponders. The Cirrus's Recoverable Data Module recorded that a traffic advisory was issued shortly after takeoff but none thereafter. Air traffic control (ATC) radar data showed that the Cessna did not produce transponder beacon returns after its departure until 2 minutes 34 seconds after the collision. Primary radar returns matching the Cessna's GPS track were recorded, but without altitude or beacon information. At 0808:21, the Cessna began transmitting a 1200 beacon code with mode-C altitude. The flight instructor acknowledged that he likely departed with the transponder off or in standby and turned it on after the collision. Postaccident testing of the Cessna's altitude, static, and transponder systems revealed no anomalies.
Weather Conditions
At 0753, the CLL automated surface observing system reported wind calm, visibility 10 miles, sky clear, temperature 7°C, dew point 3°C, and an altimeter setting of 30.35 inches of mercury. Astronomical data indicated that at the time of the collision, the sun was positioned 8–10 degrees above the horizon and about 115 degrees east of true north.