Narrative:

Recently while flying my family's newly restored C310 I had an encounter with an air carrier jet, or more correctly, the captain thought I was going to. I was traveling up the west side of the portland metropolitan area at 4500 ft. As I neared the class C airspace that surrounds pdx I tried multiple times to attain flight following from portland approach. I was concerned about possibly being in conflict with the arriving aircraft into pdx even though I was outside, and above the class C airspace. After finally reaching the controller and receiving a frequency change I gave up and simply decided to dive under the protected airspace since the mode C reporting capability of the transponder had been intermittent. At this point it should be said that, after poring over approach plates for the ILS to runway 10R approach and the seattle sectional chart, it is my belief that at no time did I enter the class C airspace or present a conflict. The altitude shown for the northwestern floor of the class C airspace is 1800 ft. By the time I was directly off the approach end of runway 10R I was through 1600 ft for 1500 ft. Off my left wing I saw and tracked an air carrier jet turning onto the final approach course. The controller called traffic for the jet at their 2 O'clock position, northbound, altitude unknown. The response from the air carrier crew was that they had the traffic in sight and it appeared to them that the traffic was cutting right across the final approach path at GS intercept. The GS intercept is at 2010 ft, 500 ft above my indicated altitude. At no time did either of us take action in regard to our relative position. The next series of comments is a bit confusing, and I now in reflection believe that I may have not been the aircraft in conflict. After watching the jet pass overhead, the crew stated that the traffic had been a definite conflict and appeared to be a piper. Furthermore there was a string of remarks regarding the fact that the aircraft should be followed and the pilot confronted. My experience and expertise are by no means boundless, however, I fail to see how a very distinctive airplane like an old, straight tail twin cessna looks anything like any piper I've ever seen. I suppose in reflection there were other options available to both the air carrier crew and myself. For my part, knowing the intermediate altitudes for the ILS final approach would have told me that staying high would have put me in less danger of confronting a bigger, faster aircraft. Additionally if I had stayed persistent at trying to get on with portland approach everyone would have known who, where, and what I was. The reaction of the air carrier crew is typical, and unfortunate. I would very much like to see the radar track of both aircraft, as well as know for sure if it was really me they were looking at. My home base is very close to pdx and my course after the incident would have been very easy to follow on radar. I almost expected the tower to tell me that portland would appreciate and expect a phone call, but nothing of the sort was mentioned.

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Original NASA ASRS Text

Title: C310 WAS FLYING AT 4500 FT, HEADING FOR AN ARPT IN THE PDX VICINITY AND TRYING TO CONTACT PDX APCH CTL WITHOUT SUCCESS. HE DECIDED TO DIVE TO 1500 FT, AN ALT BELOW THE CLASS C AIRSPACE. HE THINKS HE COMPLETED DSCNT WITHOUT PENETRATING THE CLASS C AIRSPACE. AN ACR ACFT INTERCEPTING THE RWY 10R ILS AND GS CLAIMS A CONFLICT WITH A 'PIPER' BUT IT COULD HAVE BEEN THE RPTR. RPTR DENIES ANY CONFLICT.

Narrative: RECENTLY WHILE FLYING MY FAMILY'S NEWLY RESTORED C310 I HAD AN ENCOUNTER WITH AN ACR JET, OR MORE CORRECTLY, THE CAPT THOUGHT I WAS GOING TO. I WAS TRAVELING UP THE W SIDE OF THE PORTLAND METROPOLITAN AREA AT 4500 FT. AS I NEARED THE CLASS C AIRSPACE THAT SURROUNDS PDX I TRIED MULTIPLE TIMES TO ATTAIN FLT FOLLOWING FROM PORTLAND APCH. I WAS CONCERNED ABOUT POSSIBLY BEING IN CONFLICT WITH THE ARRIVING ACFT INTO PDX EVEN THOUGH I WAS OUTSIDE, AND ABOVE THE CLASS C AIRSPACE. AFTER FINALLY REACHING THE CTLR AND RECEIVING A FREQ CHANGE I GAVE UP AND SIMPLY DECIDED TO DIVE UNDER THE PROTECTED AIRSPACE SINCE THE MODE C RPTING CAPABILITY OF THE XPONDER HAD BEEN INTERMITTENT. AT THIS POINT IT SHOULD BE SAID THAT, AFTER PORING OVER APCH PLATES FOR THE ILS TO RWY 10R APCH AND THE SEATTLE SECTIONAL CHART, IT IS MY BELIEF THAT AT NO TIME DID I ENTER THE CLASS C AIRSPACE OR PRESENT A CONFLICT. THE ALT SHOWN FOR THE NORTHWESTERN FLOOR OF THE CLASS C AIRSPACE IS 1800 FT. BY THE TIME I WAS DIRECTLY OFF THE APCH END OF RWY 10R I WAS THROUGH 1600 FT FOR 1500 FT. OFF MY L WING I SAW AND TRACKED AN ACR JET TURNING ONTO THE FINAL APCH COURSE. THE CTLR CALLED TFC FOR THE JET AT THEIR 2 O'CLOCK POS, NBOUND, ALT UNKNOWN. THE RESPONSE FROM THE ACR CREW WAS THAT THEY HAD THE TFC IN SIGHT AND IT APPEARED TO THEM THAT THE TFC WAS CUTTING RIGHT ACROSS THE FINAL APCH PATH AT GS INTERCEPT. THE GS INTERCEPT IS AT 2010 FT, 500 FT ABOVE MY INDICATED ALT. AT NO TIME DID EITHER OF US TAKE ACTION IN REGARD TO OUR RELATIVE POS. THE NEXT SERIES OF COMMENTS IS A BIT CONFUSING, AND I NOW IN REFLECTION BELIEVE THAT I MAY HAVE NOT BEEN THE ACFT IN CONFLICT. AFTER WATCHING THE JET PASS OVERHEAD, THE CREW STATED THAT THE TFC HAD BEEN A DEFINITE CONFLICT AND APPEARED TO BE A PIPER. FURTHERMORE THERE WAS A STRING OF REMARKS REGARDING THE FACT THAT THE ACFT SHOULD BE FOLLOWED AND THE PLT CONFRONTED. MY EXPERIENCE AND EXPERTISE ARE BY NO MEANS BOUNDLESS, HOWEVER, I FAIL TO SEE HOW A VERY DISTINCTIVE AIRPLANE LIKE AN OLD, STRAIGHT TAIL TWIN CESSNA LOOKS ANYTHING LIKE ANY PIPER I'VE EVER SEEN. I SUPPOSE IN REFLECTION THERE WERE OTHER OPTIONS AVAILABLE TO BOTH THE ACR CREW AND MYSELF. FOR MY PART, KNOWING THE INTERMEDIATE ALTS FOR THE ILS FINAL APCH WOULD HAVE TOLD ME THAT STAYING HIGH WOULD HAVE PUT ME IN LESS DANGER OF CONFRONTING A BIGGER, FASTER ACFT. ADDITIONALLY IF I HAD STAYED PERSISTENT AT TRYING TO GET ON WITH PORTLAND APCH EVERYONE WOULD HAVE KNOWN WHO, WHERE, AND WHAT I WAS. THE REACTION OF THE ACR CREW IS TYPICAL, AND UNFORTUNATE. I WOULD VERY MUCH LIKE TO SEE THE RADAR TRACK OF BOTH ACFT, AS WELL AS KNOW FOR SURE IF IT WAS REALLY ME THEY WERE LOOKING AT. MY HOME BASE IS VERY CLOSE TO PDX AND MY COURSE AFTER THE INCIDENT WOULD HAVE BEEN VERY EASY TO FOLLOW ON RADAR. I ALMOST EXPECTED THE TWR TO TELL ME THAT PORTLAND WOULD APPRECIATE AND EXPECT A PHONE CALL, BUT NOTHING OF THE SORT WAS MENTIONED.

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.