Medium Large Transport; Low Wing; 2 Turbojet Eng
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 3.5
Situational Awareness; Confusion
ATC Issue All Types; Conflict Ground Conflict; Less Severe; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued New Clearance; Air Traffic Control Provided Assistance; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Became Reoriented
ATC Equipment / Nav Facility / Buildings; Airport
Aircraft X landed and checked into my frequency for Gate X. I looked at that gate (not fully visible from the tower) and didn't see a tail sticking above the terminal; so I told him to taxi via A. I returned to other tasks. About 5 minutes later I looked again at that alley (there was no other traffic in that area) and saw Aircraft X stopped in the middle of the alley. I questioned him about whether he was waiting for a ground crew. It took him a moment to respond; during which time I observed him beginning a 180-degree turn in the alley. He replied that there was another aircraft in gate X. Tug 40 called for push. This delayed my cautionary advisory to Aircraft Y that there were bag carts behind his right engine and to use minimum power leaving the alley. We have been instructed that aircraft cannot push and start in this alley (they must tow all the way out to Twy A before starting) and I do not know what the wingtip clearances are in there.The pilot should have advised me before turning in to the alley that the gate was occupied. This will continue to be a problem in the new tower; since Gates X and Y are directly below the tower and not visible. We should install a downward-pointing CCTV to allow us to see whether those gates are in use.
A Ground Controller issued taxi instructions for an arriving aircraft to proceed down an alley to gate. Unknown to the Controller; that gate was already occupied by an aircraft not visible from the newly constructed Control Tower.