What happened
On August 21, 2021, at 23:30 UTC, an Airbus A300-B4-203F, registration YV562T, operated by Transcarga Intl. Airways C.A., departed Maiquetia International Airport (SVMI) for Bogota, Colombia. The flight was a scheduled cargo operation with a crew of three: the pilot, co-pilot, and flight engineer.
During the climb phase at FL170, the crew noticed attitude and direction warning lights activating on both Attitude Director Indicators (ADI). An inspection revealed a 5° pitch discrepancy between the captain's and first officer' and instruments. While maneuvering to follow instructions from Area Control Center (ACC-SVMI), the Flight Director flags deployed on both ADIs, causing the autopilot to automatically disconnect. A further 10° bank discrepancy was observed between the two instruments.
The crew attempted to rectify the failure using the Quick Reference Handbook (QRH) procedures, including switching the attitude selector, but were unsuccessful. The crew transitioned to flying via the standby horizon and visual references; however, they noted discrepancies between the terrain and the instrument readings. Consequently, the captain requested radar vectors for a return to the departure airport. During the descent, instrument functionality was recovered, and the aircraft landed safely at 00:57 UTC. There were no injuries and no damage to the aircraft.
The investigation
The JIAAC investigation involved interviewing the crew and reviewing all relevant documentation, including flight logs, maintenance records from the operator, and airworthiness certificates. Investigators also examined the maintenance history provided by the maintenance organization (OMAC-N 331).
Technical inspections were performed on the navigation instruments. Following the aircraft maintenance manual, investigators evaluated the condition of the pilot and co-pilot ADIs and the standby horizon. The investigation included a visual inspection of the cockpit and a review of the procedures followed by the crew during the emergency.