What aircraft was involved and where did it happen?

The accident on 2014-05-01 involved a Aérospatiale SA 365N « Dauphin 2 », registration F-GVFE, at Aérodrome de Maripasoula, FR.

What was the probable cause of the accident?

The accident was caused by the pilot continuing the final approach beyond the decision height while the aircraft was in an unstabilized state, exacerbated by a lack of crew coordination procedures and visual illusions caused by poor lighting.

Hard landing of medical helicopter at Maripasoula aerodrome

An Aérospatiale SA 365N Dauphin 2 sustained heavy damage during a hard landing while performing an emergency medical mission at night.

What happened

On May 1, 2014, at approximately 04:24 local time, an Aérospatelle SA 365N Dauphin 2, registration F-GVFE, was conducting an emergency medical service (HEMS) flight from Cayenne to the Maripasoula aerodrome. The crew consisted of the pilot and a safety pilot.

During the night approach, the pilot noted that one of the portable light beacons marking the landing area was non-functional. Additionally, the aircraft's steerable landing light became stuck, preventing the pilot from clearly seeing the runway centerline. While the safety pilot provided airspeed and descent rate information, they were unable to monitor the radio altimeter due to its position on the instrument panel.

As the aircraft continued the approach, the pilot failed to notice a significant deviation from the glide path. The safety pilot eventually observed the airspeed dropping to zero and felt the aircraft sinking. Despite an attempt to increase power, the helicopter performed a hard landing approximately 100 meters short of the marked landing zone, resulting in heavy damage to the airframe, including the fenestron blades and the main landing gear.

The investigation

The BEA examined the crew's performance, the aircraft's technical state, and the environmental conditions. The investigation focused on the lack of established crew resource management (CRM) procedures within the operator's manual for multi-pilot HEMS missions. Investigators also analyzed the impact of the night conditions, specifically the lack of moonlight and the malfunctioning lighting equipment, which contributed to visual illusions. The investigation also considered the physiological state of the crew, noting that the landing occurred during a period of naturally low human vigilance (between midnight and 06:00).

Findings

The primary cause of the accident was the continuation of the final approach after the decision height despite an unstabilized approach.
The lack of formal procedures and training regarding crew coordination prevented the crew from effectively monitoring flight parameters and external references.
The failure of the steerable light and a portable ground beacon made it difficult to maintain visual references.
The crew was susceptible to the "black hole" illusion (Kraft illusion), where a lack of visual cues leads to a distorted perception of height and distance.
The absence of defined task allocation between the pilot and safety pilot led to a lack of situational awareness regarding the aircraft's descent path.

Safety action

Following the accident, the operator reviewed human factors related to night VFR sensory illusions and conducted a fatigue risk study for night HEMS missions. The operator also planned to change the configuration of the portable lighting to a "T" shape to better define the approach axis.