Narrative:

On ILS to runway 10L at pdx, TRACON called out traffic 11 O'clock. 'No contact,' was our reply. We observed the traffic on TCAS, closing on us and 500 ft below us, with vertical separation decreasing. When TCAS showed us within 300 ft, we received RA 'monitor vertical speed.' it appeared on TCAS that we passed directly over the traffic with approximately 300 ft separation. Tower said traffic was a VFR aircraft executing touch and goes at pearson airport, and that this TCAS event happens all the time. I submit to you that 1) ATC is not providing adequate separation from other traffic. 2) if this operation is permitted to continue, eventually 2 aircraft are going to collide to the west of kpdx, near pearson airport. Callback conversation with reporter revealed the following information: reporter was about to execute a TCAS evasive action when the alert downgraded to a 'TA.' reporter suggest airport be closed, or ATC restr pattern operations. Supplemental information: vuo airport representative advised that they have been aware of some air carrier concerns since the ILS runway 10L approach was implemented in 1996. It is alleged that the GS not be established at its present 3.0 angle, but be designed at a steeper gradient. It was not. The representative stated that vuo was an operating airport long before there ever was a pdx airport. The representative advised that he was not aware of any reported TCAS events when the ILS runway 10R approach was the only published instrument approach procedure to runways 10. A tower specialist advised that general traffic advisories are issued to aircraft on approach to runway's 10 by TRACON and tower, when observed. ATC receives frequency remarks from aircraft advising of a TCAS alert when passing in the vicinity of vuo airport, which is inside the runway 10L final approach fix, and descending through approximately 1300 ft. Vuo traffic is required to call pdx tower prior to entering and deping vuo airport. There are aircraft frequently operation within the vuo traffic pattern on unicom frequency. Vuo has a specific airport frequency that is continuously monitored at pdx tower. It has been suggested that changing the ILS runway 10L glide path might diminish the number of TCAS alerts for aircraft passing in the vicinity of vuo airport.

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Original NASA ASRS Text

Title: ON ILS RWY 10L APCH TO PDX, B767 FLC RECEIVES TCAS RA DUE TO PATTERN TFC AT VUO ARPT. PDX ADVISED COMMON OCCURRENCE.

Narrative: ON ILS TO RWY 10L AT PDX, TRACON CALLED OUT TFC 11 O'CLOCK. 'NO CONTACT,' WAS OUR REPLY. WE OBSERVED THE TFC ON TCAS, CLOSING ON US AND 500 FT BELOW US, WITH VERTICAL SEPARATION DECREASING. WHEN TCAS SHOWED US WITHIN 300 FT, WE RECEIVED RA 'MONITOR VERTICAL SPEED.' IT APPEARED ON TCAS THAT WE PASSED DIRECTLY OVER THE TFC WITH APPROX 300 FT SEPARATION. TWR SAID TFC WAS A VFR ACFT EXECUTING TOUCH AND GOES AT PEARSON ARPT, AND THAT THIS TCAS EVENT HAPPENS ALL THE TIME. I SUBMIT TO YOU THAT 1) ATC IS NOT PROVIDING ADEQUATE SEPARATION FROM OTHER TFC. 2) IF THIS OPERATION IS PERMITTED TO CONTINUE, EVENTUALLY 2 ACFT ARE GOING TO COLLIDE TO THE W OF KPDX, NEAR PEARSON ARPT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR WAS ABOUT TO EXECUTE A TCAS EVASIVE ACTION WHEN THE ALERT DOWNGRADED TO A 'TA.' RPTR SUGGEST ARPT BE CLOSED, OR ATC RESTR PATTERN OPS. SUPPLEMENTAL INFO: VUO ARPT REPRESENTATIVE ADVISED THAT THEY HAVE BEEN AWARE OF SOME ACR CONCERNS SINCE THE ILS RWY 10L APCH WAS IMPLEMENTED IN 1996. IT IS ALLEGED THAT THE GS NOT BE ESTABLISHED AT ITS PRESENT 3.0 ANGLE, BUT BE DESIGNED AT A STEEPER GRADIENT. IT WAS NOT. THE REPRESENTATIVE STATED THAT VUO WAS AN OPERATING ARPT LONG BEFORE THERE EVER WAS A PDX ARPT. THE REPRESENTATIVE ADVISED THAT HE WAS NOT AWARE OF ANY RPTED TCAS EVENTS WHEN THE ILS RWY 10R APCH WAS THE ONLY PUBLISHED INSTRUMENT APCH PROC TO RWYS 10. A TWR SPECIALIST ADVISED THAT GENERAL TFC ADVISORIES ARE ISSUED TO ACFT ON APCH TO RWY'S 10 BY TRACON AND TWR, WHEN OBSERVED. ATC RECEIVES FREQ REMARKS FROM ACFT ADVISING OF A TCAS ALERT WHEN PASSING IN THE VICINITY OF VUO ARPT, WHICH IS INSIDE THE RWY 10L FINAL APCH FIX, AND DESCENDING THROUGH APPROX 1300 FT. VUO TFC IS REQUIRED TO CALL PDX TWR PRIOR TO ENTERING AND DEPING VUO ARPT. THERE ARE ACFT FREQUENTLY OPERATION WITHIN THE VUO TFC PATTERN ON UNICOM FREQ. VUO HAS A SPECIFIC ARPT FREQ THAT IS CONTINUOUSLY MONITORED AT PDX TWR. IT HAS BEEN SUGGESTED THAT CHANGING THE ILS RWY 10L GLIDE PATH MIGHT DIMINISH THE NUMBER OF TCAS ALERTS FOR ACFT PASSING IN THE VICINITY OF VUO ARPT.

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.