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2 air carrier aircraft at same altitude during heavy radio congestion could not talk to ATC. Visual separation finally used to separate aircraft.
| Attributes | |
| ACN | 152941 |
| Time | |
| Date | 199008 |
| Day | Fri |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | airport : sea |
| State Reference | WA |
| Altitude | msl bound lower : 7000 msl bound upper : 7000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : sea |
| Operator | common carrier : air carrier |
| Make Model Name | Medium Large Transport, Low Wing, 2 Turbojet Eng |
| Navigation In Use | Other |
| Flight Phase | cruise other descent : approach |
| Route In Use | enroute : on vectors |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | common carrier : air carrier |
| Make Model Name | Medium Large Transport, Low Wing, 2 Turbojet Eng |
| Flight Phase | cruise other descent : approach |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : cfi pilot : atp |
| Experience | flight time last 90 days : 240 flight time total : 10500 flight time type : 6500 |
| ASRS Report | 152941 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Events | |
| Anomaly | other anomaly other |
| Independent Detector | other controllera other flight crewa |
| Resolutory Action | controller : issued new clearance |
| Consequence | Other |
| Miss Distance | horizontal : 21000 vertical : 0 |
| Supplementary | |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | other |
Narrative:
I approached seatac on the malay 1 arrival, portland transition, and had turned north, heading 340 degree and had just leveled at 7000' as instructed by seattle approach and switch to frequency 133.65. Holding a speed of 210 KIAS, contact with approach was made and first officer reported at 7000' during, before and after this contact I heard seattle approach make several attempts to call air carrier Y (company aircraft) who was coming southbound on the jawbn 4 arrival. The frequency was busy but I also heard air carrier Y call level at 7000'. I became concerned and just at that point approach called me and ask if I had traffic at 12 O'clock, 4 mi. We said we had him (visibility) and approach said 'maintain visibility and descend to 4000'.' about the same time radio contact was made with air carrier Y by approach and instructed air carrier Y to turn north. It appears to me that due to frequency being very busy neither air carrier Y or seattle approach could talk to each other. Because of VFR conditions, we saw other aircraft early however, if this had been in IMC it could have had another out come.
Original NASA ASRS Text
Title: 2 ACR ACFT AT SAME ALT DURING HEAVY RADIO CONGESTION COULD NOT TALK TO ATC. VISUAL SEPARATION FINALLY USED TO SEPARATE ACFT.
Narrative: I APCHED SEATAC ON THE MALAY 1 ARR, PORTLAND TRANSITION, AND HAD TURNED N, HDG 340 DEG AND HAD JUST LEVELED AT 7000' AS INSTRUCTED BY SEATTLE APCH AND SWITCH TO FREQ 133.65. HOLDING A SPD OF 210 KIAS, CONTACT WITH APCH WAS MADE AND F/O RPTED AT 7000' DURING, BEFORE AND AFTER THIS CONTACT I HEARD SEATTLE APCH MAKE SEVERAL ATTEMPTS TO CALL ACR Y (COMPANY ACFT) WHO WAS COMING SBND ON THE JAWBN 4 ARR. THE FREQ WAS BUSY BUT I ALSO HEARD ACR Y CALL LEVEL AT 7000'. I BECAME CONCERNED AND JUST AT THAT POINT APCH CALLED ME AND ASK IF I HAD TFC AT 12 O'CLOCK, 4 MI. WE SAID WE HAD HIM (VIS) AND APCH SAID 'MAINTAIN VIS AND DSND TO 4000'.' ABOUT THE SAME TIME RADIO CONTACT WAS MADE WITH ACR Y BY APCH AND INSTRUCTED ACR Y TO TURN N. IT APPEARS TO ME THAT DUE TO FREQ BEING VERY BUSY NEITHER ACR Y OR SEATTLE APCH COULD TALK TO EACH OTHER. BECAUSE OF VFR CONDITIONS, WE SAW OTHER ACFT EARLY HOWEVER, IF THIS HAD BEEN IN IMC IT COULD HAVE HAD ANOTHER OUT COME.
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.