Investigation Summary
The accident occurred during a short scheduled flight from St. Thomas to San Juan. As the aircraft approached Puerto Rico under Instrument Flight Rules (IFR), the San Juan approach controller, who was a trainee, established radar contact. However, the trainee misidentified a radar return, placing the aircraft 10 miles closer to the airport than its actual position. This error led the controller to issue a descent clearance to 3,000 feet and a vector for the Runway 07 ILS final approach while the aircraft was still over the rugged Sierra de Luquillo mountain range. The investigation revealed that the trainee was managing five flights simultaneously and was experiencing significant personal stress, having previously been referred to psychiatric care. Furthermore, the trainee's instructor had been assigned collateral duties by a supervisor shortly before the crash, leaving the trainee without adequate supervision during a period of high workload and frequency congestion.
Final Conclusions
The NTSB determined the probable cause was the vectoring of the aircraft into mountainous terrain under IFR conditions without adequate obstruction clearance altitude. This was attributed to a controller who was performing beyond his safe capability limits and without adequate supervision. Contributing factors included the controller's personal psychological state and the supervisor's decision to assign the instructor to other duties, leaving the trainee unsupported.
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Crew Experience
Captain
First Officer
Total multi-engine time was 1,200 hours.
Systems & Failure Modes
Radar Vectoring
The process where ATC provides specific headings to pilots to navigate them to a final approach path; in this case, the vector was based on a misidentified radar position.
Minimum Safe Altitude (MSA)
The lowest altitude that provides at least 1,000 feet of clearance above all obstacles; the controller cleared the flight to 3,000 feet in an area with peaks exceeding that height.
Interesting Facts
- 01The aircraft was approximately 10 miles east of where the controller believed it to be at the time of the descent clearance.
- 02The crash site was at an elevation of approximately 2,400 feet (731 m).
- 03The trainee controller was managing five flights at the time of the accident.
- 04The controller had been referred to a psychiatrist and psychologist three years prior and reported feeling tense on the day of the crash.
- 05Weather conditions at the time prevented the pilots from seeing the mountain peaks.
- 06The aircraft's serial number (14125) was later erroneously associated with another Prinair Heron (N575PR) that crashed in 1979.
Safety Actions & Advisories
ATC Supervision Review
The investigation highlighted the danger of removing instructors from direct supervision of trainees during high-workload periods.