Narrative:

A cherokee was initially told to enter right traffic for runway 12R. When a king air checked from the northwest; I told the king air to make a straight-in approach to runway 12R. After evaluating the ground speeds; I changed the cherokee's instructions to cross over the top of the airport for left traffic to runway 12L. The cherokee read back the instructions including the runway assignment. I cleared the king air to land on runway 12R and the king air correctly read back the landing clearance for runway 12R. I cleared the cherokee to land on runway 12L; and the cherokee read back the landing clearance for runway 12L. As the cherokee approached where I determined his base leg would start; I advised him of the king air's position; told him that the king air was for the parallel runway; and that he is still number 1 for landing. He read back the information but instead said 'still number 1 for runway 12R.' I missed the read back at the time; but did hear it when the tapes were reviewed later. The king air saw the cherokee and elected to take evasive action by starting a go-around. Due to the close proximity of the cherokee to the runway; I decided that the safest course of action would be to let the cherokee continue its landing. Once the cherokee was at taxi speed; I clarified that his clearance was for runway 12L and that he had landed on the wrong runway. He said that as soon as he turned over the runway he knew he landed on the wrong runway. The king air executed a go-around and landed uneventfully after making right traffic for runway 12R. Recommendation; after reviewing the audio tapes of the event; I could clearly hear that I missed a read back when the cherokee pilot mistakenly claimed to be 'number 1 for runway 12R'. The usual recommendation would be reinforcement of read back/hear back errors. In this case; a better view of the approach end of runway 12L and 12R would have helped me determine that the cherokee was not only overshooting final; but also landing on the runway. Our tower is among the shortest I have ever seen in the country; which puts us at a disadvantage for determining an aircraft's position on final. The size difference between the two aircraft can be misleading to be able to give a 100% determination for an aircraft's position and which runway they are lined up for. Additionally; the tinted shades in our control tower are scratched and in poor repair. During sunset; this is a very serious factor as the glare off of the bent and cracked parts of the shade makes it hard to see clearly out the window.

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Original NASA ASRS Text

Title: VGT Controller described a pilot initiated go around event when traffic set up for left traffic for Runway 12L read back a landing clearance for Runway 12R and conflicted with the 12L aircraft.

Narrative: A Cherokee was initially told to enter right traffic for Runway 12R. When a King Air checked from the northwest; I told the King Air to make a straight-in approach to Runway 12R. After evaluating the ground speeds; I changed the Cherokee's instructions to cross over the top of the airport for left traffic to Runway 12L. The Cherokee read back the instructions including the runway assignment. I cleared the King Air to land on Runway 12R and the King Air correctly read back the landing clearance for Runway 12R. I cleared the Cherokee to land on Runway 12L; and the Cherokee read back the landing clearance for Runway 12L. As the Cherokee approached where I determined his base leg would start; I advised him of the King Air's position; told him that the King Air was for the parallel runway; and that he is still number 1 for landing. He read back the information but instead said 'Still number 1 for Runway 12R.' I missed the read back at the time; but did hear it when the tapes were reviewed later. The King Air saw the Cherokee and elected to take evasive action by starting a go-around. Due to the close proximity of the Cherokee to the runway; I decided that the safest course of action would be to let the Cherokee continue its landing. Once the Cherokee was at taxi speed; I clarified that his clearance was for Runway 12L and that he had landed on the wrong runway. He said that as soon as he turned over the runway he knew he landed on the wrong runway. The King Air executed a go-around and landed uneventfully after making right traffic for Runway 12R. Recommendation; after reviewing the audio tapes of the event; I could clearly hear that I missed a read back when the Cherokee pilot mistakenly claimed to be 'number 1 for Runway 12R'. The usual recommendation would be reinforcement of read back/hear back errors. In this case; a better view of the approach end of Runway 12L and 12R would have helped me determine that the Cherokee was not only overshooting final; but also landing on the runway. Our Tower is among the shortest I have ever seen in the country; which puts us at a disadvantage for determining an aircraft's position on final. The size difference between the two aircraft can be misleading to be able to give a 100% determination for an aircraft's position and which runway they are lined up for. Additionally; the tinted shades in our Control Tower are scratched and in poor repair. During sunset; this is a very serious factor as the glare off of the bent and cracked parts of the shade makes it hard to see clearly out the window.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.