by National Transportation Safety Board

“ The challenges associated with operations to Guam International Airport support its immediate consideration as a special airport requiring special pilot qualifications.
8. Although the captain apparently became confused about the glideslope's status, the flight crew had sufficient information to be aware that the glideslope was unusable for vertical guidance and should have ignored any glideslope indications while executing the nonprecision localizer-only approach.
9. Navigation receivers other than glideslope receivers may be susceptible to spurious radio signals. ”

“ The captain was fatigued, which degraded his performance and contributed to his failure to properly execute the approach.
16. Korean Air's training in the execution of nonprecision approaches was ineffective, which contributed to the deficient performance of the flight crew.
17. U.S. air carrier pilots would benefit from additional training and practice in nonprecision approaches during line operations (in daytime visual conditions in which such a practice would not add a risk factor) . ”

“ The safety issues in this report focus on flight crew performance, approach procedures, and pilot training; air traffic control, including controller performance and the intentional inhibition of the MSAW system at Guam ”