I flew for these guys for several years. Whilst the facts are not known and it could be anything at this stage, I will say that the majority of the Korean Pilots were lost without the G/S. Also, most of them had[have] a tendency to push forward and undershoot the Glide Slope in the last couple hundred feet in order to have a lower angle in the hope of the "smooth landing". These guys were obsessed with the smooth landing. Word got around about me, and when they flew with me they knew never to undershoot when I was next to them.
I am saddened by this news, although not surprised based on my personal experience.
Track Log - last 120 secs
19:26 37.5847 -122.2940 298° West 178kts 205mph 1,700ft -1,020 rate Descending
19:26 37.5900 -122.3070 297° West 169 194 1,400 -1,380 Descending
19:27 37.5988 -122.3270 299° West 145 167 800 -1,380 Descending
19:27 37.6016 -122.3340 297° West 141 162 600 -1,320 Descending
19:27 37.6045 -122.3410 298° West 134 154 400 -900 Descending
19:27 37.6073 -122.3480 297° West 123 142 300 -840 Descending
19:27 37.6103 -122.3550 298° West 109 125 100 -120 Descending
19:28 37.6170 -122.3740 294° West 85 98 200 120 Climbing