The board was critical of the airline's lack of adequate simulator training on the aircraft before placing it into passenger service, and made recommendations to the FAA that all large turbine-engine aircraft used in air transportation be equipped with a flight recorder. Over 90 percent of the primary structural components of the aircraft and most of the systems components were recovered by investigators. They found that at the moment of impact, the flaps were approximately in the approach position, the landing gear was extended, and propeller blade angles were relatively uniform and consistent with the power readings obtained from the recovered aircraft instruments and consistent with the testimony of the crew regarding the power being used during the approach. Neither of the two vertical speed indicator mechanisms were recovered. Both altimeters were recovered, but since the diaphragms of both had been overstressed due to submersion, it was impossible to establish the calibration or accuracy of either altimeter before the crash. Investigators obtained all of the maintenance records including pilot complaints of all operators, civil and military, of the type of altimeter used in the flight. None of the reported incidents involved more than one of the altimeters installed at a time, and after reviewing the possibility of a simultaneous failure of both altimeters, the CAB concluded that it would involve such an extreme mathematical improbability that it chose to reject that theory as well as reject portions of the testimony of the surviving crew members. It also concluded that after consideration of all possible scenarios, that a failure of just one of the altimeters was also unlikely to have occurred. Based upon eyewitness testimony and analysis of the point of impact, the CAB concluded that it was likely that one or more of the pilots had misread the altimeter due to their unfamiliarity with the new style. It also concluded that there was a possibility that the crew had misread the vertical speed indicators, which also used a different scale than what had been used in older aircraft or in the training received by the captain. The CAB concluded that all of the required airport, boundary, and runway lights were on and functioning at the time of the accident. However, because the lights were slanted upward at between three and five degrees, and because of a dike located between the end of runway 22 and the water, the CAB concluded that they would not have been visible to the crew because of the aircraft's premature descent below the cloud level. The CAB's conclusions were soundly criticized by the president of the Air Line Pilots Association, who called the report "grossly inaccurate in a number of respects", and that the report failed to satisfactorily explain the reason for the accident and assumed factors that had not been established by fact.