What happened
On February 16, 2014, a Sikorsky S-76C helicopter, registration PR-CHI, operated by BHS Braz. Hel. Services Taxi Aéreo S.A., was performing an offshore passenger transport mission. The flight originated from Cabo Frio (SBCB) with the intent to visit the helideck of the drillship Aban Abraham (NS-07) and the P-63 platform.
After completing landings at both maritime units, the crew returned to the Aban Abraham for a subsequent landing. During the final approach, the crew noted visible movements of the helideck. Although the crew briefly considered an aborted landing (go-around), they ultimately decided to proceed with the touchdown. Moments before contact, a sudden heave movement of the vessel caused the helideck to strike the aircraft's landing gear. The impact caused the right landing gear leg to retract, leaving the helicopter tilted at a 15-degree angle. All 12 occupants, including the two crew members and ten passengers, evacuated the aircraft without injury, though the aircraft sustained light damage.
The investigation
CENIPA's investigation focused on the accuracy of the environmental data provided to the crew and the decision-making process during the approach. Investigators reviewed Flight Data Monitoring (FDM) records, which confirmed that all aircraft systems and engines were operating normally.
The investigation examined the Helideck Monitoring System (HMS) on the NS-07 and the communication protocols used by the radio operator. While the radio operator provided pitch, roll, and heave (P/R/H) data approximately 20 minutes before landing that appeared to be within safe limits, records showed that significant heave peaks exceeding operational limits had occurred in the minutes immediately preceding the accident. These critical fluctuations were not communicated to the flight crew.
Findings
- Pilot judgment: The crew's decision to proceed with the landing despite observing significant deck movement contributed to the event.
- Support systems: The lack of a standardized time interval for radio operators to report maximum P/R/H values meant that the crew relied on outdated information that did not reflect the rapid change in sea conditions.
Safety action
Following the investigation, technical orders were updated to ensure that safety parameters for helideck operations include the monitoring of peak movements over at least a 20-minute window. Additionally, several maritime units have since been equipped with modernized HMS technology that provides real-time visual alerts (red or green lights) based on the last 20 minutes of motion data.