曝光台 注意防骗
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The first officer‘s failure to activate and identify the ILS frequency earlier in the approach prevented the flight crew from recognizing that the airplane was off course and below the glideslope. The fast/slow indicator on the EADI resembles the glideslope indicator and is visible on the EADI at all times, whereas the glideslope indicator only appears on the screen once an ILS frequency has been activated. Postaccident flight simulations revealed that the fast/slow indicator would have been centered within one dot during the approach sequence and that the indications would have been consistent with the first officer‘s comments about the glideslope if he had mistaken the fast/slow indicator for the glideslope indicator.
The first officer did not switch the VOR frequency to the ILS frequency until about 1 minute before impact. When the first officer realized that he had not switched to the ILS frequency, he should have called for a missed approach because the airplane was not properly configured for the approach and was not receiving proper vertical guidance during the most critical phase of the flight. Once the first officer selected the ILS frequency, the glideslope indicator would have appeared on the screen and both pilots‘ displays would have shown a full-scale deviation below the glideslope and a full-scale or near full-scale deviation of the localizer; however, the CVR did not record either pilot mention the glideslope deviation. The fast/slow indicator would have remained visible on the EADI even after the ILS frequency was selected, which may explain why the pilots did not immediately notice the glideslope indicator deviation after the first officer selected the ILS frequency. Therefore, the pilots most likely mistook the fast/slow indicator for the glideslope indicator throughout the approach sequence.
The Safety Board is concerned that the first officer switched the frequency of a primary navigational aid and failed to inform the captain. If the pilot-not-flying takes such actions without first checking with or simultaneously informing the flying pilot, confusion can occur, as evidenced by the captain‘s remark, —What happened? Did you change my frequency?“ In this case, because the airplane was at such a low altitude (about 1,000 feet) in IMC, such a major change should have prompted the captain to immediately initiate a missed approach.
Shortly after activating the ILS frequency, the first officer stated, —we‘re all squared away now.“ The captain replied, —I don‘t know if I can get back on it [the ILS localizer] in time.“ The first officer stated, —yeah you will. you‘re squared away now.“ These comments indicate that the pilots were focused on correcting the localizer deviation. The first officer dismissed the captain‘s concerns, and the captain did not proceed to assert his authority. As noted, earlier in the approach, the flight crew had attempted unsuccessfully to activate the flight director APR mode, and no evidence indicates that either pilot tried to reactivate the APR mode on their flight directors once the ILS frequency was selected. Therefore, the flight crew continued to perform the approach without the advantage of flight director guidance. The CVR did not record the pilots making any of the required altitude callouts, except at 0614:40, when the first officer announced that they had reached the DH of 244 feet. The airplane hit the light pole immediately thereafter.
FDR data show that the airplane exceeded a descent rate of 1,000 fpm within 500 feet of the touchdown elevation, which was outside of the stabilized approach window. In addition, although the localizer deviation was less than one dot by the time the airplane reached 500 feet, the localizer would have shown a full-scale or near full-scale deviation of the localizer when the first officer initially activated the ILS frequency. Both of these factors should also have prompted the flight crew to initiate a missed approach.
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Crash During Approach to Landing Gulfstream G-1159A (G-III),(14)
