the crew suggested instead that an actuator on the #7 slat had failed, causing its inadvertent deployment. the ntsb rejected this as improbable and attributed the extension of the flaps to the deliberate actions of the crew. the crew claimed that such failures had happened on other 727s prior and subsequent to this incident. the ntsb report noted that between 1970 and 1973, seven separate cases involving a single leading edge slat extension and separation were reported, but none of these reports indicated whether or not the slat extension was due to flight crew involvement. records after 1974 did include this information, and (other than flight 174) only two slat extension problems were reported between 1974 and the close of the ntsb's investigation in 1981, one of which was inadvertently caused by the flight crew.