Dip 6´ wide 4 inches deep across full width of rwy aprx 660´ fr thld Rwy 09. Flare stack at gas plant 0.7NM E of YOP NDB may occasionally produce a flame reaching aprx 600 AGL, 2181 ASL. Lgtd twr aprx 6.6NM N A/D (N58 35 10 W119 18 17) 2621 ASL (421 AGL)
Effective 0901Z 0901Z 29 March 2018 to 0901Z 24 May 2018