Investigation Summary
The flight was a late-night scheduled service from San Juan to Ponce. Because the Mercedita Airport control tower was closed at the time of arrival, the crew was responsible for their own landing clearance and runway separation. While some early reports and contemporary sources suggested heavy fog was a factor, the NTSB investigation (AAR-75-17) confirmed that weather conditions at the time of the accident were actually clear with calm winds. After touching down, the crew initiated a go-around maneuver. During this transition, the aircraft was rotated to a nose-high attitude that exceeded its performance capabilities at that airspeed, leading to an aerodynamic stall. Post-crash investigation revealed that the right main gear was retracted and locked, while the left was retracted but unlocked. All four propeller governors were found in the low-pitch (high RPM) position, which is consistent with a go-around attempt. The aircraft crashed 260 feet south of the runway centerline. Initial NTSB findings were heavily influenced by eyewitness reports of a Puerto Rico Ports Authority vehicle on the runway, leading to a probable cause citing an 'unauthorized vehicle.' However, the case was reopened three years later when new evidence proved the suspected vehicle had left the airport 15 minutes prior to the crash. The NTSB subsequently issued a revised report removing the vehicle from the probable cause.
Final Conclusions
The National Transportation Safety Board determined the probable cause was the loss of directional control during a go-around from a landing attempt. Control was lost when the aircraft was over-rotated at too low an airspeed to sustain flight. The crew's reasons for rejecting the landing are not known.
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Crew Experience
Captain
Age 28
First Officer
Age 27
Systems & Failure Modes
DH.114 Heron Aerodynamics
The aircraft stalled due to over-rotation during a low-speed go-around, where the angle of attack exceeded the critical limit before sufficient airspeed was gained.
Interesting Facts
- 01The control tower at Mercedita Airport was closed at the time of the accident.
- 02Weather at the time of the accident was clear and winds were calm, contradicting initial reports of fog.
- 03The aircraft was destroyed by the impact and subsequent events.
- 04The captain had over 3,000 hours of experience on the DH-114 Heron type.
- 05The NTSB officially amended the probable cause three years after the initial report.
Safety Actions & Advisories
NTSB Investigation Re-opening Procedures
This case highlighted the importance of verifying eyewitness testimony against physical and log-based evidence, leading to the NTSB's willingness to reopen and amend reports (AAR-75-17) when conclusive contradictory evidence is presented.
Known Controversies & Unanswered Questions
The Unauthorized Vehicle Theory
Reference ↗The NTSB initially concluded an airport vehicle caused the crash, but later retracted this after evidence showed the vehicle had left the airport 15 minutes earlier.