Casualties unknown

1994-07-19: Air Tractor AT-501 (N6073J) — Marianna, AR

Marianna, AR, US

On July 19, 1994, an Air Tractor AT-501 (registration N6073J) was involved in an aviation accident near Marianna, AR. Investigators recorded the probable cause as: The pilot's failure to ensure adequate takeoff performance in high-density altitude and wet grass conditions, resulting in insufficient climb gradient to clear trees. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 1781061362Data APIEditorial standards

A pilot attempted takeoff from a wet, grass runway with a tailwind and high temperatures. The aircraft settled back onto the strip before becoming airborne but struck trees at the end of the field.

What happened

The flight crew initiated takeoff operations from an unpaved sod strip under challenging environmental conditions. The runway surface was wet and covered with tall grass, which likely increased rolling resistance and reduced acceleration efficiency. Meteorological data indicated an outside air temperature of 90 degrees Fahrenheit, creating high-density altitude conditions that degrade engine performance and lift generation. Additionally, the aircraft encountered a five-knot quartering tailwind during the roll.

During the initial climb phase, the aircraft failed to gain sufficient altitude and settled back onto the runway surface. Recognizing the imminent danger, the pilot applied full available power and adjusted the flap configuration to optimize lift. To reduce weight and improve climb performance, the crew began jettisoning the onboard fuel load. Despite these corrective actions, the aircraft remained airborne but lacked the energy necessary to clear the tree line situated at the end of the runway.

The aircraft subsequently collided with the trees and crashed. The combination of high temperature, wet grass surface, and tailwind component critically compromised the takeoff performance envelope, preventing the aircraft from achieving a safe climb gradient.

The investigation

Examination of the event focused on the interaction between the aircraft's performance capabilities and the environmental factors present during the takeoff roll. The pilot's account confirmed that the aircraft settled back onto the runway shortly after liftoff. The decision to dump fuel indicates an attempt to reduce gross weight to improve climb rate, a standard emergency procedure for weight-imbalanced or underpowered climbs. However, the available runway length and surface conditions were insufficient to allow the aircraft to recover from the settling phase and clear the obstacle.

Findings

The primary factors contributing to this accident included:

  • High density altitude due to 90-degree temperatures
  • Wet, grass-covered runway surface increasing drag
  • Five-knot quartering tailwind reducing groundspeed efficiency
  • Insufficient climb performance to clear the tree line

The aircraft was unable to achieve the necessary climb gradient to clear obstacles after a failed initial ascent. The environmental conditions exceeded the safe operating limits for the takeoff configuration.

Safety message

Pilots must carefully calculate takeoff performance requirements before attempting operations from unpaved or wet surfaces, especially in high-temperature conditions. Tailwinds significantly reduce acceleration and lift generation. If an aircraft settles back onto the runway during takeoff, immediate action to reduce weight and apply full power is critical, but success depends on remaining runway length and surface conditions.

Probable cause

The pilot's failure to ensure adequate takeoff performance in high-density altitude and wet grass conditions, resulting in insufficient climb gradient to clear trees.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001206X01749. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.