Narrative:

On initial contact with bellingham tower 10 mi southeast from the field; the tower controller instructed me to report 3 mi southeast and to expect a right turn which was an unusual instruction from what I had expected (left turn for a straight-in for runway 34). I read back the instruction and proceeded to descend from my cruising altitude of 2500 ft for the approach. A short while later; the controller advises me that a P3 was coming in on a straight-in approach for the airport and for me to report him in sight. I looked to my 7 O'clock position and saw the P3 about 3 or 4 mi behind me on approach to runway 34. I acknowledged that I had the P3 in sight. I was about 6 or 7 mi southeast of the runway at this point and the controller instructed me to follow the P3 and to remain well east of the centerline for runway 34. I acknowledged his instruction and continued with my approach to the airport at a reduced speed so that the P3 can overtake me on the left. A short while later; an inbound cessna; that the tower had been in contact with; reported that he is entering the downwind for runway 34. The controller acknowledges the call and informs the cessna that he is #3 to follow me. The cessna pilot acknowledges the call. My position then was about 3 mi southeast of the runway and the P3 is at my 8 O'clock position and about to overtake me on the left. At that time the radio became busy and I could not get in a call to instruct the tower that I was about to begin a right 270 degree turn in order to get behind the P3. At that very moment I saw the cessna that the tower has been in contact with on a wide right downwind for runway 34 approaching on my right and eventually passing below me by a couple hundred ft. This surprised me as runway 34 is normally left downwind. The controller then queried the cessna for his position and the pilot reported that he was abeam the P3 who is now on a 1 mi final. The cessna apparently did not have me in sight. The controller then asks me for a position report and I responded that I am approaching the shoreline and that the cessna just went underneath me. There was some momentary confusion and the tower then instructed the cessna that he's now #2 to follow the P3. The cessna pilot acknowledged and the tower then instructed me to follow the cessna. I acknowledged the instruction and made a right 270 degree turn to follow the cessna. When I was finally on a long final for runway 34; the tower queried me why I didn't follow the P3 as originally instructed and I explained the situation to him and he responded with 'I think I see what happened there.' in retrospect; I did not adequately maintain a full situational awareness of the cessna's location relative to the airport and my aircraft in the class D environment. I was expecting the cessna to be on a left downwind on the western side of the airport and did not verify with the tower that this was the case. I should've inquired about the cessna's location relative to mine which may have alerted me to react sooner instead of watching the P3 overtake me on my left. I probably should've executed the right 180 degree turn sooner so as to put myself on a very extended right downwind relative to the P3 and ahead of the cessna.

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Original NASA ASRS Text

Title: PA28 ARR TO BLI; INSTRUCTED TO FOLLOW P3 ON STRAIGHT IN APCH TO RWY 34; EXPERIENCED NMAC WITH CESSNA ON DOWNWIND.

Narrative: ON INITIAL CONTACT WITH BELLINGHAM TWR 10 MI SE FROM THE FIELD; THE TWR CTLR INSTRUCTED ME TO RPT 3 MI SE AND TO EXPECT A R TURN WHICH WAS AN UNUSUAL INSTRUCTION FROM WHAT I HAD EXPECTED (L TURN FOR A STRAIGHT-IN FOR RWY 34). I READ BACK THE INSTRUCTION AND PROCEEDED TO DSND FROM MY CRUISING ALT OF 2500 FT FOR THE APCH. A SHORT WHILE LATER; THE CTLR ADVISES ME THAT A P3 WAS COMING IN ON A STRAIGHT-IN APCH FOR THE ARPT AND FOR ME TO RPT HIM IN SIGHT. I LOOKED TO MY 7 O'CLOCK POS AND SAW THE P3 ABOUT 3 OR 4 MI BEHIND ME ON APCH TO RWY 34. I ACKNOWLEDGED THAT I HAD THE P3 IN SIGHT. I WAS ABOUT 6 OR 7 MI SE OF THE RWY AT THIS POINT AND THE CTLR INSTRUCTED ME TO FOLLOW THE P3 AND TO REMAIN WELL E OF THE CTRLINE FOR RWY 34. I ACKNOWLEDGED HIS INSTRUCTION AND CONTINUED WITH MY APCH TO THE ARPT AT A REDUCED SPD SO THAT THE P3 CAN OVERTAKE ME ON THE L. A SHORT WHILE LATER; AN INBOUND CESSNA; THAT THE TWR HAD BEEN IN CONTACT WITH; RPTED THAT HE IS ENTERING THE DOWNWIND FOR RWY 34. THE CTLR ACKNOWLEDGES THE CALL AND INFORMS THE CESSNA THAT HE IS #3 TO FOLLOW ME. THE CESSNA PLT ACKNOWLEDGES THE CALL. MY POS THEN WAS ABOUT 3 MI SE OF THE RWY AND THE P3 IS AT MY 8 O'CLOCK POS AND ABOUT TO OVERTAKE ME ON THE L. AT THAT TIME THE RADIO BECAME BUSY AND I COULD NOT GET IN A CALL TO INSTRUCT THE TWR THAT I WAS ABOUT TO BEGIN A R 270 DEG TURN IN ORDER TO GET BEHIND THE P3. AT THAT VERY MOMENT I SAW THE CESSNA THAT THE TWR HAS BEEN IN CONTACT WITH ON A WIDE R DOWNWIND FOR RWY 34 APCHING ON MY R AND EVENTUALLY PASSING BELOW ME BY A COUPLE HUNDRED FT. THIS SURPRISED ME AS RWY 34 IS NORMALLY L DOWNWIND. THE CTLR THEN QUERIED THE CESSNA FOR HIS POS AND THE PLT RPTED THAT HE WAS ABEAM THE P3 WHO IS NOW ON A 1 MI FINAL. THE CESSNA APPARENTLY DID NOT HAVE ME IN SIGHT. THE CTLR THEN ASKS ME FOR A POS RPT AND I RESPONDED THAT I AM APCHING THE SHORELINE AND THAT THE CESSNA JUST WENT UNDERNEATH ME. THERE WAS SOME MOMENTARY CONFUSION AND THE TWR THEN INSTRUCTED THE CESSNA THAT HE'S NOW #2 TO FOLLOW THE P3. THE CESSNA PLT ACKNOWLEDGED AND THE TWR THEN INSTRUCTED ME TO FOLLOW THE CESSNA. I ACKNOWLEDGED THE INSTRUCTION AND MADE A R 270 DEG TURN TO FOLLOW THE CESSNA. WHEN I WAS FINALLY ON A LONG FINAL FOR RWY 34; THE TWR QUERIED ME WHY I DIDN'T FOLLOW THE P3 AS ORIGINALLY INSTRUCTED AND I EXPLAINED THE SITUATION TO HIM AND HE RESPONDED WITH 'I THINK I SEE WHAT HAPPENED THERE.' IN RETROSPECT; I DID NOT ADEQUATELY MAINTAIN A FULL SITUATIONAL AWARENESS OF THE CESSNA'S LOCATION RELATIVE TO THE ARPT AND MY ACFT IN THE CLASS D ENVIRONMENT. I WAS EXPECTING THE CESSNA TO BE ON A L DOWNWIND ON THE WESTERN SIDE OF THE ARPT AND DID NOT VERIFY WITH THE TWR THAT THIS WAS THE CASE. I SHOULD'VE INQUIRED ABOUT THE CESSNA'S LOCATION RELATIVE TO MINE WHICH MAY HAVE ALERTED ME TO REACT SOONER INSTEAD OF WATCHING THE P3 OVERTAKE ME ON MY L. I PROBABLY SHOULD'VE EXECUTED THE R 180 DEG TURN SOONER SO AS TO PUT MYSELF ON A VERY EXTENDED R DOWNWIND RELATIVE TO THE P3 AND AHEAD OF THE CESSNA.

Data retrieved from NASA's ASRS site as of May 2009 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.