Narrative:

At xx:46Z, small aircraft X called 7 mi south for landing. I issued the pilot an airport advisory. At xx:50Z, small aircraft Y, called departing runway 32. I issued an airport advisory to the aircraft and inadvertently neglected to issue the small aircraft X as traffic ('reported 7 mi south 4 mins ago'). The small aircraft Y then proceeded to taxi onto the runway, as the small aircraft X was on short final for runway 32. The small aircraft X made a turn to the right and leveled off at about 25', and then continued around the small aircraft Y and turned left off the runway at about 20' off the ground to the ramp across the grass. The small aircraft Y stopped short of the runway past the hold line. My inadvertent report of 'no reported traffic', set up the situation. In addition, pilots, who are ultimately responsible for the safety of their aircraft, must be aware of the situation, as well. In this case, if the small aircraft X had made a call 30 seconds prior to the small aircraft Y taxiing onto the runway, when the airport advisory was issued to the second aircraft (small aircraft Y), small aircraft X's evasive maneuver probably would not have been necessary. (Note: I did not see the small aircraft X until it was making its evasive maneuver). Small aircraft X was an executive business aircraft.

Related reports:

Google
 

Original NASA ASRS Text

Title: AT A NON-CONTROL ARPT, A LNDG ACFT CAME VERY CLOSE TO ACFT THAT TAXIING INTO POSITION FOR TKOF.

Narrative: AT XX:46Z, SMA X CALLED 7 MI S FOR LNDG. I ISSUED THE PLT AN ARPT ADVISORY. AT XX:50Z, SMA Y, CALLED DEPARTING RWY 32. I ISSUED AN ARPT ADVISORY TO THE ACFT AND INADVERTENTLY NEGLECTED TO ISSUE THE SMA X AS TFC ('RPTED 7 MI S 4 MINS AGO'). THE SMA Y THEN PROCEEDED TO TAXI ONTO THE RWY, AS THE SMA X WAS ON SHORT FINAL FOR RWY 32. THE SMA X MADE A TURN TO THE R AND LEVELED OFF AT ABOUT 25', AND THEN CONTINUED AROUND THE SMA Y AND TURNED L OFF THE RWY AT ABOUT 20' OFF THE GND TO THE RAMP ACROSS THE GRASS. THE SMA Y STOPPED SHORT OF THE RWY PAST THE HOLD LINE. MY INADVERTENT RPT OF 'NO RPTED TFC', SET UP THE SITUATION. IN ADDITION, PLTS, WHO ARE ULTIMATELY RESPONSIBLE FOR THE SAFETY OF THEIR ACFT, MUST BE AWARE OF THE SITUATION, AS WELL. IN THIS CASE, IF THE SMA X HAD MADE A CALL 30 SECS PRIOR TO THE SMA Y TAXIING ONTO THE RWY, WHEN THE ARPT ADVISORY WAS ISSUED TO THE SECOND ACFT (SMA Y), SMA X'S EVASIVE MANEUVER PROBABLY WOULD NOT HAVE BEEN NECESSARY. (NOTE: I DID NOT SEE THE SMA X UNTIL IT WAS MAKING ITS EVASIVE MANEUVER). SMA X WAS AN EXECUTIVE BUSINESS ACFT.

Data retrieved from NASA's ASRS site as of July 2007 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.