What happened
On August 3, 2015, a Boeing 737-800 was performing an approach to landing at LPFR under adverse weather conditions. During the approach, the flight crew lost visual contact with the runway. Consequently, the crew decided to execute a missed approach procedure and divert to an alternate airport.
During the execution of the missed approach, the aircraft's Ground Proximity Warning System (GPWS) activated, issuing a "DON'T SINK" alert to the cockpit.
The investigation
An investigation into the incident examined flight parameters recorded during the maneuver. The analysis focused on the flight path and the aircraft's configuration during the transition from the approach to the climb.
Findings
Technical analysis revealed that the GPWS alert was triggered by an insufficient climb gradient. This lack of performance was caused by an error in the aircraft's configuration, specifically the unintended setting of the flaps to position 5 instead of the required position 15.
The investigation concluded that the primary cause was improper crew performance while executing the missed approach procedure.
Safety action
Following a review of the incident within the training department, the crew was assigned to a remedial simulator training session.