Narrative:

My initial plan was to depart pearson VFR to the northwest, and contact pdx approach for a clearance into pdx. However, an airline pilot at pearson told me there was some sort of informal 'quasi-tower-to-tower' procedure wherein you contact the pdx tower on takeoff for a quick clearance into pdx. I obtained the current pdx ATIS. They were landing runways 10, but the runway in use at pearson was 26 (confirmed by the windsock and the tetrahedron). Just after takeoff, climbing out of 4000', I contacted pdx tower, idented myself and requested a VFR clearance into pdx. I was at 1000' and had turned to the northwest (the standard VFR departure procedure under the arsa cutout) when the controller responded with, 'small aircraft squawk XXXX, enter left base for 1-0 left.' when I received the clearance, I repeated it back to the controller, set the transponder, and turned about 110 degrees left to effect a base entry as directed. However, by the time I completed the turn, I had crossed the extended centerline of 10L and was approaching the centerline of 10R. I spotted an light transport aircraft about 1/2 to my right on the G/south for 10R. At that time, the frequency was very busy, and before I could break in to ask the controller what he wanted me to do, I had passed above and in front of the approaching aircraft and crossed the extended centerline of 10R. The crew of the light transport apparently did not see me until they were nearly past, and it startled them to the point they complained to the tower. No evasive action was required for me to safely avoid the light transport aircraft. I advised the tower I had the commuter in sight and requested instructions. The controller told me, 'turn left 180, enter right base for 10L, clear to land.' I complied and landed. The ground controller told me to phone the tower after I parked. I phoned as instructed, and discussed the incident with the tower supervisor, he was very friendly, and during the course of the discussion told me that when the first controller told me to '...enter left base for 10L,' what he really wanted was for me to continue northwest, then make a right 180 degree turn to enter left base. I told him that expectation was neither stated nor implied in the spoken instructions. The supervisor told me he would talk to the controller and to the pilot of the commuter aircraft, and that when coming to pdx from pearson, I should contact the pdx tower prior to takeoff.

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Original NASA ASRS Text

Title: ACFT FLEW THROUGH THE FINAL APCH COURSE OF A RWY AND CAME VERY CLOSE TO AN ACFT ON FINAL TO THE OTHER PARALLEL RWY.

Narrative: MY INITIAL PLAN WAS TO DEPART PEARSON VFR TO THE NW, AND CONTACT PDX APCH FOR A CLRNC INTO PDX. HOWEVER, AN AIRLINE PLT AT PEARSON TOLD ME THERE WAS SOME SORT OF INFORMAL 'QUASI-TWR-TO-TWR' PROC WHEREIN YOU CONTACT THE PDX TWR ON TKOF FOR A QUICK CLRNC INTO PDX. I OBTAINED THE CURRENT PDX ATIS. THEY WERE LNDG RWYS 10, BUT THE RWY IN USE AT PEARSON WAS 26 (CONFIRMED BY THE WINDSOCK AND THE TETRAHEDRON). JUST AFTER TKOF, CLBING OUT OF 4000', I CONTACTED PDX TWR, IDENTED MYSELF AND REQUESTED A VFR CLRNC INTO PDX. I WAS AT 1000' AND HAD TURNED TO THE NW (THE STANDARD VFR DEP PROC UNDER THE ARSA CUTOUT) WHEN THE CTLR RESPONDED WITH, 'SMA SQUAWK XXXX, ENTER LEFT BASE FOR 1-0 LEFT.' WHEN I RECEIVED THE CLRNC, I REPEATED IT BACK TO THE CTLR, SET THE XPONDER, AND TURNED ABOUT 110 DEGS LEFT TO EFFECT A BASE ENTRY AS DIRECTED. HOWEVER, BY THE TIME I COMPLETED THE TURN, I HAD CROSSED THE EXTENDED CENTERLINE OF 10L AND WAS APCHING THE CENTERLINE OF 10R. I SPOTTED AN LTT ACFT ABOUT 1/2 TO MY RIGHT ON THE G/S FOR 10R. AT THAT TIME, THE FREQ WAS VERY BUSY, AND BEFORE I COULD BREAK IN TO ASK THE CTLR WHAT HE WANTED ME TO DO, I HAD PASSED ABOVE AND IN FRONT OF THE APCHING ACFT AND CROSSED THE EXTENDED CENTERLINE OF 10R. THE CREW OF THE LTT APPARENTLY DID NOT SEE ME UNTIL THEY WERE NEARLY PAST, AND IT STARTLED THEM TO THE POINT THEY COMPLAINED TO THE TWR. NO EVASIVE ACTION WAS REQUIRED FOR ME TO SAFELY AVOID THE LTT ACFT. I ADVISED THE TWR I HAD THE COMMUTER IN SIGHT AND REQUESTED INSTRUCTIONS. THE CTLR TOLD ME, 'TURN LEFT 180, ENTER RIGHT BASE FOR 10L, CLR TO LAND.' I COMPLIED AND LANDED. THE GND CTLR TOLD ME TO PHONE THE TWR AFTER I PARKED. I PHONED AS INSTRUCTED, AND DISCUSSED THE INCIDENT WITH THE TWR SUPVR, HE WAS VERY FRIENDLY, AND DURING THE COURSE OF THE DISCUSSION TOLD ME THAT WHEN THE FIRST CTLR TOLD ME TO '...ENTER LEFT BASE FOR 10L,' WHAT HE REALLY WANTED WAS FOR ME TO CONTINUE NW, THEN MAKE A RIGHT 180 DEG TURN TO ENTER LEFT BASE. I TOLD HIM THAT EXPECTATION WAS NEITHER STATED NOR IMPLIED IN THE SPOKEN INSTRUCTIONS. THE SUPVR TOLD ME HE WOULD TALK TO THE CTLR AND TO THE PLT OF THE COMMUTER ACFT, AND THAT WHEN COMING TO PDX FROM PEARSON, I SHOULD CONTACT THE PDX TWR PRIOR TO TKOF.

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.