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 Further, although the approach procedure specified that at least 1,440 feet msl should be maintained after passing the GUQQY outer marker and until passing the UNZ VOR, flight 801 descended below 1,440 feet about 2.1 DME before reaching the UNZ VOR. (None of the indications of UNZ station passage would have been presented on the flight crew's instrument panels at any time before impact.)

CVR information indicated that the captain was flying the airplane on autopilot during the approach. As flight 801 descended on the approach, the captain twice commanded the entry of lower altitudes into the airplane's altitude selector before the airplane had reached the associated step-down fix. After the captain heard the first officer call out "approaching fourteen hundred [feet]" about 0140:33, as the airplane was passing 5 DME at 2,400 feet msl, the captain directed the first officer to reset the altitude selector to 1,440 feet, replacing the step-down altitude of 2,000 feet before the autopilot had captured that altitude or reached the GUQQY outer marker/1.6 DME fix. Further, about 0141:33, with the flight neither having leveled off at 1,440 feet msl nor reached the UNZ VOR step-down fix, the captain instructed the first officer to set 560 feet, the MDA, in the altitude selector.

The altitude selector provides the basis for the altitude alert's aural annunciations and the autopilot's altitude capture functions. The captain's premature orders to reset the altitude selector indicated that he had lost awareness of the airplane's position along the final approach course. Therefore, as a result of the captain's commanded input to the altitude selector, the autopilot continued to descend the airplane prematurely through the 2,000- and 1,440-foot intermediate altitude constraints of the approach procedure. The CVR comments indicated no awareness by the captain that the airplane was descending prematurely below the required intermediate altitudes.

2.4.1.1 Approach Briefing

Korean Air cockpit procedures call for an approach (landing) briefing before descent. Also, company training instructs the flying pilot to conduct an approach briefing before descent. According to the Korean Air 747 landing briefing checklist card and testimony by Korean Air officials during the Safety Board's public hearing, this briefing should include a discussion of weather conditions, a review of the instrument approach