What happened
On April 28, 1973, at approximately 09:00 UTC, a Piper PA-25-260 Pawnee aircraft with registration CS-AGC was engaged in agricultural spraying operations over the Herdade de Palma near Alcácer do Sal, Portugal. The operator, Sanagri - Serviços Aéreos de Sanidade Agrícola Ld., had the aircraft registered under its name.
During the operation, the pilot attempted to abort a spray run and execute a 360-degree left turn to re-enter the aborted row. As the aircraft progressed through approximately 135 degrees of the turn, it encountered a moderate tailwind from the north (8-10 knots). This wind condition caused the aircraft to sink gradually.
Ahead of the aircraft's nose was an elevation covered with pine trees. The pilot recognized that under these conditions, he would have difficulty clearing this obstacle. In response, the pilot applied full available power and simultaneously activated the emergency release lever to jettison the solid spray product. Because the product was solid, it took time to be expelled, resulting in minimal altitude recovery.
The pilot was unable to avoid striking the canopy of one of the pine trees. Upon impact, the aircraft lost control, crashed into the ground approximately 50 meters ahead, caught fire, and slid about 40 meters before colliding with a smaller tree. The aircraft eventually came to rest after completing a 180-degree rotation along its trajectory. The pilot abandoned the aircraft after it stopped.
The investigation
The GPIAAF investigated the accident involving CS-AGC, a Piper PA-25-260 Pawnee (construction number 25/5220), powered by a Lycoming O-540-G1A5 engine. The aircraft was owned and operated by Sanagri for agricultural services.
The pilot, aged 34, held a valid pilot license with qualifications for single-engine land aircraft, flight instructor status, and an instrument rating. His medical certificate was valid until August 18, 1973. He had accumulated 4,800 total flight hours, including 650 hours in the Pawnee type. On the day of the accident, he had flown for 20 minutes and made two landings.
The aircraft's last periodic inspection was recorded on February 26, 1973, at 684:05 total time (100-hour interval). The engine had been inspected at 696:00 hours. Documentation indicated the aircraft was airworthy, though some records were lost in the post-crash fire.
Weather conditions were partly cloudy with a moderate north wind of 8-10 knots. The aircraft was equipped with an onboard fire extinguisher.
Findings
The investigation established that the primary cause of the accident was the moderate tailwind during the climb phase after initiating the turn, which contributed to the loss of altitude control. Additionally, the delay in expelling the solid spray product due to its physical state reduced the aircraft's ability to gain sufficient altitude to clear the tree line.
The combination of these factors prevented the pilot from successfully clearing the obstacle, leading to the collision with the pine trees and subsequent crash.
Safety action
No specific safety recommendations or actions taken are recorded in this report beyond the standard investigation process.