The de Havilland Heron crashed after a failed go-around; the cause is still unknown.

Prinair Flight 191 (Puerto Rico International Airlines) crashed at 23:17 EST on June 24, 1972, killing five of the 20 passengers and crew. The flight was a regularly scheduled flight between San Juan's Luis Muñoz Marín International Airport (SJU) and Mercedita International Airport (PSE) in Ponce.

The aircraft involved in the crash was a 17-year-old de Havilland DH-114 Prinair Heron 2B piloted by 28-year-old Captain Donald Price, a very experienced airman with 8,300 flight hours that included 3,000 flying the Heron. The co-pilot for the flight was 27-year-old Gary Belejeu, who only had 1,400 flight hours, including 102 hours in the DH-114.

The flight took off on time from San Juan for the short hop over the island to Ponce. Because it was late at night, the control tower at Mercedita Airport was closed. This left the flight crew responsible for ensuring that the runway was clear of all obstacles before landing.

After touching down on the runway, the plane's pilot decided to abort the landing and perform a go-around. Whoever had control of the aircraft over-rotated, causing the plane to stall at a low level and crash. Of the 20 people onboard the plane, both pilots and three passengers died. The remaining 15 passengers were injured, seven severely.

The National Transportation Safety Board (NTSB) was brought in to examine what could have been responsible and concluded that an unauthorized vehicle on the runway could be to blame. They thought the plane's pilot may have seen a vehicle on the runway and aborted the landing to avoid a collision. The sudden maneuver resulted in an over-rotation of the aircraft at too low an airspeed, which ultimately led to the crash.

Eyewitnesses say they saw a set of lights on the runway as the aircraft was landing. Another witness said that they saw a Puerto Rico Ports Authority vehicle being parked shortly after the crash and that the person driving the vehicle was acting suspiciously.

It later came to light that the person suspected of driving the unauthorized vehicle had left the airport 15 minutes before the crash happened. Three years after the incident, the NTSB felt compelled to reopen the investigation. The second investigation found that there was not a vehicle on the runway and that the reason for the go-around was unknown.

Following WWII, aircraft manufacturer de Havilland began work on a twin-engine passenger plane to replace the Dragon Rapide and compete with the DC-3. The result was the 11-passenger DH 104 Dove. In the late 1940s, a stretched version of the Dove with two added engines was designed for regional and commuter routes.

During its existence, Prinair operated the de Havilland Heron piston-engined aircraft for its services. Prinair later introduced their own version of the Heron after replacing the original 250 hp Gipsy Queen 30-2 engines for more powerful 300 hp Continental IO-520 engines. At one point, Prinair had 20 de Havilland Heron planes making it the largest operator of the Heron in the world.

Journalist - Mark is an experienced travel journalist having published work in the industry for more than seven years. His enthusiasm for aviation news and wealth of experience lends itself to some excellent insight, with his work cited in Forbes amongst other publications. Based in Alicante, Spain.