What happened
On June 6, 2019, a Cessna 402B, registration HK5126, was performing a scheduled regional flight from Nuquí to Quibdó, Colombia. The aircraft was carrying two pilots and four passengers. During the approach to runway 13 at El Caraño Airport, the crew was managing heavy traffic and following instructions from Air Traffic Control to maintain spacing.
As the aircraft approached the runway, the crew performed landing checklists but deferred the extension of the landing gear until the aircraft reached a lower speed. Upon touchdown, the landing gear remained in the retracted position. The aircraft's engines and propellers struck the runway surface, causing both engines to stop abruptly. The fuselage slid approximately 700 meters along the asphalt before coming to a halt. All 6 occupants were able to evacuate the aircraft without injuries.
The investigation
The GRIAA investigation focused on the sequence of the landing and the mechanical state of the aircraft. Investigators found that while the aircraft was airworthy and maintenance schedules were up to date, a specific mechanical issue existed: the microswitch responsible for the landing gear warning alarm was out of calibration. Specifically, when power was reduced below 13 psi in the manifold, the alarm failed to trigger, removing a critical auditory warning that would have alerted the crew to the gear's status.
Furthermore, the investigation examined the crew's performance and the operator's safety management systems. It was noted that the crew's attention was divided by intense ATC communications and surrounding traffic, leading to the omission of the gear extension step.
Findings
- The primary cause was the crew's failure to extend the landing gear due to a lack of situational awareness.
- A miscalibrated microswitch prevented the landing gear warning alarm from activating during the final approach.
- Crew complacency led to the omission of critical landing checklists.
- Deficiencies were identified in the operator's Safety Management System (SMS), specifically regarding oversight, maintenance practices for gear indication systems, and a weak safety reporting culture.
- Maintenance practices regarding the adjustment of landing gear detection systems were found to be inadequate.