Synopsis
On 2 December 2019 at approximately 06:30 UTC, a WACO YMF aircraft (registration HS-MWM) operated by Virus Pattaya Company Limited was conducting a takeoff from runway 34 at a temporary take-off and landing area in Banthi subdistrict, Lamphun province, Thailand. The pilot occupied the back seat and a passenger the front seat. During the takeoff roll, the aircraft veered to the right of the runway centerline. The pilot applied excessive corrective input (over-control), causing the aircraft to wobble before veering to the left side of the runway. The aircraft struck an obstacle, rolled on the ground, and came to a stop. The aircraft was heavily damaged, but both occupants were uninjured.
Flight History
On 30 November 2019 at 23:30 UTC, the same pilot and passenger departed from Eastern Pattaya Airfield in Chonburi province en route to Pai airport, Mae Hong Son province, with planned stops at Phitsanulok, Nan, and the temporary landing area at Banthi. They overnighted at Nan Nakhon airport. On 2 December 2019 at 03:00 UTC, they departed Nan for Banthi, arriving at 04:00 UTC for refueling. After a pre-flight inspection, the pilot started the engine and taxied to the threshold of runway 34 at 06:25 UTC. While increasing engine power for takeoff, the aircraft deviated right, leading to the accident sequence.
Injuries to Persons
Neither the pilot nor the passenger sustained injuries.
Damage to Aircraft
The aircraft was heavily damaged. The left upper wing sustained leading edge damage along its entire span, with two significant dents. The left lower wing had a dent near the landing light and a puncture on the bottom. The right lower wing was broken 190 centimeters from the wingtip; one interplane strut was bent. The right main landing gear was bent and its fairing broken. Both propeller blades were damaged: one blade had slight frontal damage and one blade tip was damaged. The aileron on the right lower wing was damaged and bent. The lower fuselage had slight abrasion, and the right fuselage near the landing gear was heavily damaged.
Personnel Information
The pilot, aged 42, held a Norwegian Private Pilot Licence issued by the Department of Civil Aviation (now CAAT) on 17 July 2012, last renewed 17 July 2017, valid until 16 July 2022, with a Single Engine Land rating. A valid Class 2 medical certificate was issued on 21 November 2019. Total flight time was 544:57 hours, with 24:15 hours on the WACO YMF, all within the previous 90 days. The rest period before the accident flight was 16 hours.
Aircraft Information
The aircraft was a WACO YMF F5C biplane, manufactured in 2003 by WACO Classic Aircraft Corporation, USA. It had one engine and two seats, with tailwheel ground control. The engine was a Jacobs R755B2M (serial 19383, manufactured 1943). The propeller was a Sensenich Wood W96JB468. The aircraft had a standard Certificate of Airworthiness valid from 25 September 2019 to 24 September 2022. Time since new was 330:51 hours; the last periodic maintenance (100-hour) was performed on 4 March 2019 at 307:00 hours. Take-off mass on the accident flight was 1,309.07 kilograms.
Meteorological Information
No weather reports were available at the accident site. The nearest weather report from Chiang Mai International Airport (METAR) at 06:30 UTC indicated surface wind from 170 degrees at 6 knots, visibility 10 kilometers or more, few clouds at 35,000 feet, temperature 31°C, dew point 18°C, and pressure 1015 millibars.
Conclusions
The investigation determined the causes of the accident to be the pilot's over-control and the pilot's insufficient experience flying the WACO YMF aircraft. Contributing factors included wet grass and an area used for farming, after harvesting and burning the field beside the runway.