Investigation Summary
TAI Flight 307 was a multi-leg international service from Paris to Abidjan via Bordeaux and Bamako. After a two-hour stopover in Bordeaux, the aircraft departed Runway 23 into darkness and light drizzle. The flight profile was unusual: after reaching approximately 30 to 100 feet, the aircraft stopped climbing and maintained a nearly level or slightly descending trajectory. The investigation highlighted a specific aerodynamic characteristic of the DC-7C where, during the initial climbout, a slight increase in speed could result in a significant decrease in the rate of climb. Without external visual cues or rigorous instrument monitoring, the crew likely allowed the aircraft to settle back toward the ground. The aircraft struck pine trees approximately 2,950 meters from the runway end, breaking apart and catching fire. Rescue efforts were severely hampered by the lack of roads in the dense forest, forcing emergency workers to trek the final half mile on foot.
Final Conclusions
The Investigation Board concluded the accident was likely caused by a combination of factors including the lack of external visual references and the rapid sequence of cockpit operations. Reconstructed flights demonstrated that if optimum climbing speed is not strictly maintained and the altimeter is not carefully watched, the aircraft can inadvertently return to the ground. While the board listed potential mechanical failures (engine issues or instrument malfunctions) as possibilities, the primary focus remained on the pilot's inability to maintain a climb profile in the absence of visual cues.
Photographic Evidence (1)
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Crew Experience
Captain
First Officer
Systems & Failure Modes
Altimeter
The investigation noted that the altimeter may not have been watched carefully enough to detect the lack of climb.
Artificial Horizon
Potential wrong indications or lack of precision in the artificial horizon were cited as possible contributing factors.
Wright R-3350-30W Engines
The board considered the possibility of a failure in one or more of the four radial piston engines.
Interesting Facts
- 01The aircraft was nearly new, having been delivered to TAI less than two years prior to the accident.
- 02The crash site was located in a dense pine forest, which caused the fuselage to break up upon impact.
- 03Weather at the time included light drizzle and a 3-knot wind, providing poor visual references for a night departure.
- 04Of the 54 fatalities, all 9 crew members and 45 passengers were killed.
- 05There were 56 passengers on board; 12 initially survived the impact, but one died later in the hospital, leaving 11 survivors.
- 06The investigation used flight reconstruction to prove that speed increases during climbout could cause altitude loss.
Safety Actions & Advisories
DC-7C Climb Profile Awareness
The investigation highlighted a critical aerodynamic phase during the initial climb of the DC-7C where a slight increase in speed could paradoxically lead to a loss of altitude. Operators were cautioned to maintain optimum climbing speed and strictly monitor altimeters during night or low-visibility departures to prevent inadvertent descent.