What happened
On November 1, 1979, a hot air balloon, registration HB-BBE, was conducting a promotional flight from Valangin toward Biel with five passengers on board. After several unsuccessful attempts to land near the shores of Lake Biel due to shifting winds, the pilot attempted a low-altitude flight over the western part of the city of Biel, targeting an open area near a regional hospital.
During this low-altitude transit, the balloon's basket struck the cross atop the spire of the Sainte Marie Catholic Church. The impact was forceful enough to tear the cross from its mountings, causing it to fall onto a nearby roof. Following the collision, the balloon ascended rapidly to an altitude of 450 meters. Faced with dwindling fuel reserves, the pilot eventually managed to land the Colt Balloons Ltd aircraft on a nearby motorway.
The investigation
The investigation established that the pilot was properly licensed and the aircraft was airworthy, with no technical malfunctions contributing to the event. The inquiry examined the flight path, noting that the pilot had bypassed safer landing opportunities in open terrain in favor of a low-altitude flight over a populated urban area. The investigation also reviewed the fuel status, finding that the remaining gas was only sufficient for approximately 20 minutes of flight time, which likely pressured the pilot to find an immediate landing site.
Findings
- The primary cause of the accident was inappropriate flight tactics.
- The pilot flew at an altitude significantly below the required minimum of 300 meters over a built-up area.
- The pilot underestimated the inertia of the large balloon, which hindered the ability to maneuver away from obstacles.
- The obstacle (the church spire) was identified too late to prevent the collision.