The NTSB examined why the plane was unable to climb once it departed the runway. After conducting airplane performance studies, the NTSB determined that the events of Flight 1141 could only be explained by the aircraft attempting to take off without its flaps and slats extended to the proper take-off configuration. The aircraft's instability and sudden roll to the right was consistent with known performance of the Boeing 727 with the flaps and slats retracted. The captain continued to pull back on the control column in an attempt to keep the plane's nose raised, which created turbulence over the rear-mounted engines and caused the compressor surges. However, the NTSB concluded that the compressor surges would not have significantly reduced the engines' thrust, and that the plane's failure to gain speed was due to aerodynamic drag on the aircraft due to the high angle of attack, rather than a loss of engine thrust. The NTSB examined the CVR and noted that neither pilot is heard announcing the deployment of the flaps or slats, nor is the sound of the flap lever movement heard. The NTSB considered it extremely unlikely that a pilot would have moved either the flaps or the slats without announcing their actions to the rest of the flight crew. Based on the aircraft's failure to climb at takeoff speed, its roll instability, the position of the flap's jackscrews in the fully retracted position, and the absence of sounds indicating the flaps or slats were deployed, the NTSB determined that the plane's failure to climb resulted from the flight crew's failure to deploy the flaps and slats as required by the pre-flight checklist.