What happened
On August 16, 2008, at approximately 10:37 AM, a Grumman AA-5B flying from Aschaffenburg toward Wangerooge entered the Frankfurt/Main Class C airspace. While operating under Visual Flight Rules (VFR), the pilot climbed to 5,500 ft, which placed the aircraft within controlled airspace (the lower limit of which is 1,500 ft).
During the flight, the Grumman AA-5B crossed the flight paths of two separate commercial airliners on final approach. At 10:37 AM, the light aircraft crossed the path of an Airbus A320-211 approaching runway 25L. The crew of the Airbus A320-211 responded to a TCAS Resolution Advisory (RA) by initiating a climb. Radar data indicated a horizontal separation of 0.9 NM and a vertical separation of 400 ft between the aircraft.
One minute later, at 10:38 AM, the Grumman AA-5B crossed the path of a second Airbus A320-211 approaching runway 25R. In this instance, the air traffic controller instructed the Airbus crew to level off at FL 60 to maintain separation. Radar records showed a horizontal distance of 1.2 NM and a vertical distance of 500 ft between the two aircraft.
The investigation
The BFU investigation examined radar recordings from the air traffic service provider and radio communications between the controller and the Airbus crews. The investigation also reviewed the pilot's statements regarding his flight profile and navigation.
Findings
- The pilot of the Grumman AA-5B had climbed to 5,500 ft to fly above a cloud layer near Mainaschaff, which resulted in the aircraft entering the Frankfurt Class C airspace.
- The pilot reported that he was attempting to establish contact with Langen Information but was distracted by a radio setting error that prevented him from communicating effectively.
- Navigation was further complicated by difficult terrain visibility, as the pilot could only find sporadic holes in the cloud cover.
- No injuries or damage to aircraft or third parties were reported.