Small Aircraft; Low Wing; 1 Eng; Retractable Gear
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) .2
Situational Awareness
ATC Issue All Types; Deviation / Discrepancy - Procedural Clearance; Ground Incursion Taxiway
Human Factors; ATC Equipment / Nav Facility / Buildings
Aircraft X was inbound from the north assigned a left downwind for RWY 35L; on initial call I widened out his downwind approach by 10 degrees as he appeared to be tracking up final for RWY 17R. He entered the left downwind for RWY 35L I cleared him to land on RWY 35L following a Cessna in the pattern ahead. Aircraft X read back the clearance correctly for landing RWY 35L. I then asked the pilot to confirm he had the Cessna ahead insight; he informed he did not. I then told Aircraft X to extend his downwind and I would call his base to allow for appropriate separation with the Cessna ahead. Then told Aircraft X to turn his base and again cleared to land RWY 35L; pilot acknowledged the clearance but did not read back the runway. Pilot asked for a wind-check and was given one. I observed what looked like from the tower Aircraft X lined up for RWY 35L. Then turned my attention to moving pattern traffic around for a runway change. The GC/CIC (Ground Control/ Controller in Charge) then stated he landed on TWY A. I looked back and confirmed he was in fact rolling out on the TWY. I contacted Aircraft X and informed him it appeared he just landed on TWY A and to contact GC for further instructions.I recommend we have a tower with a better perspective and closer proximity to the approach ends of 35L and 35R.
COS Tower controller reported an aircraft landed on a taxiway.