On rotate out of Johannesburg the aircraft systems gave a spurious warning that the thrust reverser doors (Used on landing to assist in braking the aircraft) on engines 2 + 3 were unlocked (possibly open or deployed leading to the engine thrust being deployed forward not rearward).
A potentially dangerous situation as a thrust reverser deployment in flight, especially at low speed/low level can cause a disastrous departure from controlled flight! The system has three interlocks which should prevent actual deployment in flight.
The crew could not know what that actual deployment of the thrust reverser doors was, however an actual deployment would most certainly be felt by the flying pilot!
As a damage security system the 744 automatically retracts the mid and inboard leading edge slats to prevent damage to the slats from the thrust of the engine now coming forward. As JNB is a high airfield in hot conditions with a heavy aircraft these lift enhancing devices on the leading edge are vital, all take off and climb out speeds would be calculated using LE slats deployed. Loss of those, without quick intervention could lead to a stall.
The aircraft stick shaker is there to warn the crew of impending approach toward the stall. Thus, at the onset of stick shaker the crew selected full Take Off/ Go Around (TOGA) power, brought the landing gear up to reduce drag and flew the aircraft away from a potentially dangerous situation. Normal take offs are conducted at a 'flexible' power dependant on the conditions of the day to save on engine wear.
Excellently handled and I think I can see the next 6 monthly simulator check scenario now.