Narrative:

I was working local control. At XA24 helicopter X called from northeast of airport and requested SVFR clearance through control zone, north to south, at or below 1000'. Ground control coordinated with sea approach and received clearance for X. I gave SVFR clearance to X to go through the control zone. (I thought I had restr the aircraft to at or below 1500', but later I found out I did not give any altitude to the aircraft after listening to the tape). At XA27 X called to request route change from east side to west side, which I approved. At XA29, helicopter X requested to climb to 1500', which I approved (after listening to the tape many times people at the facility determined that the pilot had said climb through 1500'). At XA30 the pilot of X said he was leveling at 2500', and that time I told him to maintain SVFR at or below 1500' while in control zone. There was mlt Y at 2500' approximately 3-4 mi southwest of helicopter X which was pointed out to the pilot and he acknowledged it. I think this situation occurred because I thought I gave correct clearance to the pilot and the pilot did not read back the clearance. Also, I did not hear correctly when he said, 'climb through 1500',' rather I thought I heard 'climb to 1500'' which I thought was not any problem because I thought I said, 'maintain SVFR conditions at or below 1500' while in control zone.' I should work on listening skills.

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Original NASA ASRS Text

Title: TWR CTLR ALLOWED HELICOPTER ON SVFR CLRNC TO CLIMB TO WRONG ALT AND INTO TRSA AIRSPACE. SET UP POSSIBLE LESS THAN STANDARD SEPARATION WITH MLT ACFT.

Narrative: I WAS WORKING LCL CTL. AT XA24 HELI X CALLED FROM NE OF ARPT AND REQUESTED SVFR CLRNC THROUGH CTL ZONE, N TO S, AT OR BELOW 1000'. GND CTL COORDINATED WITH SEA APCH AND RECEIVED CLRNC FOR X. I GAVE SVFR CLRNC TO X TO GO THROUGH THE CTL ZONE. (I THOUGHT I HAD RESTR THE ACFT TO AT OR BELOW 1500', BUT LATER I FOUND OUT I DID NOT GIVE ANY ALT TO THE ACFT AFTER LISTENING TO THE TAPE). AT XA27 X CALLED TO REQUEST ROUTE CHANGE FROM E SIDE TO W SIDE, WHICH I APPROVED. AT XA29, HELI X REQUESTED TO CLB TO 1500', WHICH I APPROVED (AFTER LISTENING TO THE TAPE MANY TIMES PEOPLE AT THE FAC DETERMINED THAT THE PLT HAD SAID CLB THROUGH 1500'). AT XA30 THE PLT OF X SAID HE WAS LEVELING AT 2500', AND THAT TIME I TOLD HIM TO MAINTAIN SVFR AT OR BELOW 1500' WHILE IN CTL ZONE. THERE WAS MLT Y AT 2500' APPROX 3-4 MI SW OF HELI X WHICH WAS POINTED OUT TO THE PLT AND HE ACKNOWLEDGED IT. I THINK THIS SITUATION OCCURRED BECAUSE I THOUGHT I GAVE CORRECT CLRNC TO THE PLT AND THE PLT DID NOT READ BACK THE CLRNC. ALSO, I DID NOT HEAR CORRECTLY WHEN HE SAID, 'CLB THROUGH 1500',' RATHER I THOUGHT I HEARD 'CLB TO 1500'' WHICH I THOUGHT WAS NOT ANY PROB BECAUSE I THOUGHT I SAID, 'MAINTAIN SVFR CONDITIONS AT OR BELOW 1500' WHILE IN CTL ZONE.' I SHOULD WORK ON LISTENING SKILLS.

Data retrieved from NASA's ASRS site as of August 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.