What happened
On 8 February 2005, a Boeing B737-800, registration ZS-SJD, was performing a scheduled domestic flight from Johannesburg International Airport to Cape Town International Airport. During the takeoff roll on Runway 21R, the pilot-in-command noted that the aircraft's acceleration seemed slower than usual, leading to a suspicion of a flat tire. At the time, the aircraft was facing a 90-degree crosswind from the left.
As the aircraft became airborne, the crew encountered difficulties maintaining directional control as the plane began rolling to the right. In an attempt to stabilize the aircraft, the pilot applied significant right rudder and 69.6 degrees of left aileron. This resulted in a cross-control state that caused the co-pilot to declare a "MAYDAY" due to concerns regarding controllability at a low altitude. Once the aircraft reached approximately 1000ft AGL, the captain corrected the inputs, and the aircraft resumed a normal climb rate of 1100ft/min. The flight proceeded to its destination without further issues, with 0 fatalities and 0 injuries recorded.
The investigation
The investigation examined the aircraft's maintenance history and the environmental conditions at the time of the incident. The aircraft had recently undergone a Check ‘A’ just one day prior to the event. Meteorological data indicated thunderstorm activity in the vicinity of the airport. The investigators also reviewed the flight crew's actions regarding engine power and control surface inputs during the critical moments after liftoff.
Findings
- The primary cause of the incident was the pilot's application of crossed controls, specifically 4 degrees of right rudder combined with 69.6 degrees of left aileron.
- A contributing factor was the presence of a crosswind and nearby thunderstorm activity, which likely prompted an overreaction to the aircraft's rightward roll.
- The investigation concluded that the combination of lateral acceleration, roll-yaw coupling, and the specific control forces used created a flight condition that mimicked engine failure or loss of control.