Narrative:

At approximately XA38 I departed small aircraft X IFR sunol 3 departure. Local position combined working moderate to heavy traffic mostly departures. X was 1 1/2 mi off departure end runway 30. I then taxied commuter Y into position runway 30L and hold. Pilot acknowledged instructions. Aircraft Y was also a sunol 3 departure and I had to wait about 2 more mins before enough separation would exist between X and Y. However, I was also departing aircraft from 2 other runways. At XA40 I observed aircraft Y at taxiway G (5000 ft down runway 30L) nose up attitude. I then looked at my coordinator and asked who was departing and after that was established, did I clear aircraft Y for takeoff? I immediately scanned the radar for small aircraft X while coordinator was on landline with bay trying to coordinate what to do. I realized that a decision was imminent to avoid collision. Both aircraft were going to enter IFR conditions within seconds. Aircraft Y was also 50-70 KTS faster. I observed X leaving 1500 ft 2 1/2 mi off departure end. Aircraft Y was 1 mi behind and I turned Y to 360 degree. I issued X as traffic. Y reported X in sight. Bay gave approval for 360 degree for sunol. Bay turned X behind Y. I usually state a reason for the hold when not obvious. This time I did not. I felt that I took the most appropriate action with regard to time constraints. Also, aircraft characteristics were taken into consideration. Tapes verified Y was never issued takeoff clearance. 360 degree is not a standard departure heading. Should have turned aircraft Y left to 270 degree or 140 degree but then would have had a system deviation for violating bay's airspace. Resolution: if takeoff clrncs will not be issued for more than 2 mins, do not put aircraft into position on runway.

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Original NASA ASRS Text

Title: LTSS BTWN SMA AND COMMUTER ACFT. PLTDEV.

Narrative: AT APPROX XA38 I DEPARTED SMA X IFR SUNOL 3 DEP. LCL POS COMBINED WORKING MODERATE TO HVY TFC MOSTLY DEPS. X WAS 1 1/2 MI OFF DEP END RWY 30. I THEN TAXIED COMMUTER Y INTO POS RWY 30L AND HOLD. PLT ACKNOWLEDGED INSTRUCTIONS. ACFT Y WAS ALSO A SUNOL 3 DEP AND I HAD TO WAIT ABOUT 2 MORE MINS BEFORE ENOUGH SEPARATION WOULD EXIST BTWN X AND Y. HOWEVER, I WAS ALSO DEPARTING ACFT FROM 2 OTHER RWYS. AT XA40 I OBSERVED ACFT Y AT TAXIWAY G (5000 FT DOWN RWY 30L) NOSE UP ATTITUDE. I THEN LOOKED AT MY COORDINATOR AND ASKED WHO WAS DEPARTING AND AFTER THAT WAS ESTABLISHED, DID I CLR ACFT Y FOR TKOF? I IMMEDIATELY SCANNED THE RADAR FOR SMA X WHILE COORDINATOR WAS ON LANDLINE WITH BAY TRYING TO COORDINATE WHAT TO DO. I REALIZED THAT A DECISION WAS IMMINENT TO AVOID COLLISION. BOTH ACFT WERE GOING TO ENTER IFR CONDITIONS WITHIN SECONDS. ACFT Y WAS ALSO 50-70 KTS FASTER. I OBSERVED X LEAVING 1500 FT 2 1/2 MI OFF DEP END. ACFT Y WAS 1 MI BEHIND AND I TURNED Y TO 360 DEG. I ISSUED X AS TFC. Y RPTED X IN SIGHT. BAY GAVE APPROVAL FOR 360 DEG FOR SUNOL. BAY TURNED X BEHIND Y. I USUALLY STATE A REASON FOR THE HOLD WHEN NOT OBVIOUS. THIS TIME I DID NOT. I FELT THAT I TOOK THE MOST APPROPRIATE ACTION WITH REGARD TO TIME CONSTRAINTS. ALSO, ACFT CHARACTERISTICS WERE TAKEN INTO CONSIDERATION. TAPES VERIFIED Y WAS NEVER ISSUED TKOF CLRNC. 360 DEG IS NOT A STANDARD DEP HDG. SHOULD HAVE TURNED ACFT Y L TO 270 DEG OR 140 DEG BUT THEN WOULD HAVE HAD A SYS DEV FOR VIOLATING BAY'S AIRSPACE. RESOLUTION: IF TKOF CLRNCS WILL NOT BE ISSUED FOR MORE THAN 2 MINS, DO NOT PUT ACFT INTO POS ON RWY.

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.