Background
The Swedish Coastguard (Kustbevakningen) aircraft registered SE-IVF, with call sign 585, was tasked with two routine maritime surveillance flights over the southern Baltic Sea and along the south and west coasts of Sweden, including the Kattegatt. The crew comprised two pilots and two system operators. The first flight of the day was planned from Ronneby to Malmö/Sturup airport, with a route passing the southern tip of Öland, reporting point KOLJA, south of Gotland, and then back via KOLJA to a point south of Smygehamn.
Flight
Takeoff occurred at 11:09 from runway 19 under Visual Flight Rules (VFR) weather conditions. The aircraft was assigned an altitude band of 1500 feet or lower. Immediately after takeoff, the crew requested and performed a 360-degree left turn at about 500 feet around the airfield. The air traffic controller later learned that this maneuver may have been intended to show the aircraft to a work experience student.
After the circuit, KBV 585 continued with the flight plan, climbing south then turning left. During the climb, the aircraft exceeded the assigned altitude of 1500 feet, reaching 2000 feet before requesting and receiving clearance to climb to 2500 feet. The pilots then changed radio frequency without reporting to the area controller, which was described as unusual by the controller.
The flight proceeded north-west according to the plan. Tasks included environmental and fishing surveillance, as well as searching for traces from a previously sunken barge. No problems were reported during the flight.
Fly-by
While en route south-west after turning at the southern tip of Gotland, the crew received a request from the KBV coordination center to perform a fly-by over Falsterbo. A study visit by two school classes was taking place at the KBV base at the Falsterbo canal. The pilots accepted and revised the final part of the flight plan.
At 13:23, KBV 585 came over the coast at Falsterbonäset on a north-northwesterly course along the canal. The aircraft went out over the sea, made a left turn, and returned to approach the base. It then performed a second fly-by at low speed and low altitude over the base and along the canal in the opposite direction (south-south-east). The flight path was partly over the canal, partly over the beach and buildings along the north-eastern shore. Beyond the far end of the canal, the aircraft executed a 180-degree left turn, first climbing then descending. On its final approach, it came over the beach on the north-eastern side of the canal on a north-westerly course, later altered to north-north-westerly as it crossed the canal again.
Accident
As the aircraft neared the base, it began wing tipping. After two or three wing tippings, when the aircraft was approximately above the bridge at the north-west entrance to the canal, a loud bang was heard. The entire left wing separated from the aircraft and fell into the basin. The aircraft rolled onto its back and also fell into the basin somewhat further out. The impact created a large cascade of water. The remains of the aircraft and wing quickly sank to the bottom. Various pieces of wreckage floated on the surface at the point of impact. All four persons on board sustained fatal injuries. The accident occurred at position 55° 25' N 012° 56' E, at sea level.
Probable Cause
The official investigation determined that the accident was caused by an inadequate maintenance system with respect to inspections for fatigue cracks. A contributing factor to the crack formation was an unsuitable design of the attachment of the wings to the aircraft fuselage.