What happened
On 15 July 2006, a ROBIN DR 400-180, registration F-GTPB, departed Gorna Orahovica, Bulgaria, as part of a group of aircraft flying to Osijek, Croatia. The aircraft was carrying a pilot and three passengers.
While flying through Serbian airspace, the group encountered increasing cloudiness that reached the ground. While other aircraft in the formation requested climbs to higher altitudes to maintain visual flight rules (VFR), the pilot of F-GTP_PB reported a descent to 3,000 feet. The aircraft's last radar contact occurred at 08:57:15 UTC at an altitude of 3,000 feet. Shortly thereafter, the pilot could no longer be reached by Belgrade Approach Control or the other aircraft in the group.
Following a two-day search operation, the wreckage was located in a heavily forested, difficult-to-access area near Krivi Vir, Republic of Serbia. The impact was found to have occurred at a very steep angle, causing the aircraft to disintegrate upon hitting the terrain. All four fatalities were confirmed at the site.
The investigation
The investigation examined the flight history, meteorological conditions, and communications transcripts. Investigators analyzed radar records and recovered GPS data from the wreckage. The investigation also reviewed the aircraft's maintenance history and the pilot's flight experience.
Analysis of the wreckage indicated the propeller was rotating at a low speed at the time of impact. Meteorological data confirmed that while visibility was generally good, the area was experiencing increasing cloud layers and potential fog in ravines, which prompted other pilots in the group to climb to avoid IMC (Instrument Meteorological Conditions).