70th Place, southeast of the runway, in a residential area of the city's West Lawn community, one and a half blocks west of Marquette Park. Victims The three-man flight crew died, along with 40 of the 55 passengers. The crash destroyed five houses and damaged three others, killing two people on the ground. Survivors credited the actions of stewardesses as heroes, as the stewardesses called out to survivors to exit the plane through a hole in the rear of the plane. Investigation The National Transportation Safety Board (NTSB) was notified of the accident at 14:40 CST and immediately dispatched an investigation team to the scene. Agents of the Federal Bureau of Investigation (FBI) were on the scene about 45 minutes after the crash, before any investigators from the NTSB. The Flight Data Recorder (FDR) on board the aircraft was not functioning at the time of the crash due to a mechanical failure. Fortunately, the ARTS-III (Automated Terminal Radar Services) system at nearby O'Hare International Airport was in operation at the time of the accident, and saved recorded transponder data on magnetic tape. The tapes were analyzed extensively and compared to Boeing flight profile data to develop the course, speed, rate of descent, and altitudes of the plane as it made its approach to Chicago Midway. The system had tracked the plane from a position of east of its antenna site to close to the crash site. The Cockpit Voice Recorder (CVR) was working normally and the tape in that "black box" was relatively undamaged, which enabled the NTSB to sequence it in time with the readings of ARTS-III. The NTSB then was able to determine the power output of the engines, at any given point in time, with CVR tape sound analysis. That correlation, CVR with ARTS-III, allowed the NTSB to reconstruct the flight's performance, and to determine that the stick shaker first sounded 6 to 7 seconds after the plane leveled off at MSL ( AGL) and continued until ground impact. No evidence was found of sabotage or foul play. The NTSB Report described nonsurvivors’ injuries in unusual detail, finding this “necessary” because of the allegations “injected into the publicity surrounding” the accident. The Board’s official finding of the probable cause of the accident was the captain’s failure to exercise positive flight management. The Analysis section of the Report concludes with a paragraph to “emphasise” that the accident sequence resulted from that failure, and “reiterate[d] its often-expressed concern about the apparent lack of crew coordination and cockpit discipline during nonprecision approaches”. It went on to make comparison with the then-recent Eastern Airlines hard landing at Fort Lauderdale and Southern Airways accident at Huntington Tri-State, and refers the reader to the Report on the Southern Airways accident which quotes in full an FAA Bulletin raising issues of training and culture. The CVR showed cockpit discussion of the FDR fault and it has since been reported as fact that the crew had become distracted by it. At 14:27 the final-descent checklist was completed and the first officer then called out "thousand feet", apparently in reference to the plane's altitude reaching MSL, a height of only above the ground at the eventual impact point. According to the airline’s procedures, the First Officer should by then have been monitoring instruments, and calling out conformance to the specified descent profile, every . A similar 1000ft call and instrument check should have been made at a height above ground of 1000ft (1000 AGL) but had been omitted. Ground impact occurred at 14:28. The NTSB sought to understand how the rapid descent had been accomplished. From