deteriorating weather last night may cause the crash
METAR ZYLD 241600Z 00000MPS 0600 FG NSC 13/13 Q1015=
METAR ZYLD 241500Z 00000MPS 0600 FG NSC 13/13 Q1015=
METAR ZYLD 241400Z 15001MPS 1000 BR NSC 12/12 Q1014=
METAR ZYLD 241300Z 15001MPS 8000 NSC 13/13 Q1014=
The deteriorating visibility caused by thickening fog in ZYLD from 2100 to 2400, Aug. 24, local time. Limited round trip fuel on board might forced the captain broke non-precision approach visibility limit (>2800 meters) and made a landing decision. According to the Henan Airlines ZYLD operation manual, night flight is "generally" not permitted after Sep. 1 each year in this airport but no reason is provided. The airport even does not equipped with ILS, only non-precision approach procedures are available. Poor weather coupled with poor navigation system, as well as incorrect decision making by crews might put down the plane.