Narrative:

At XX28Z climbing out of seoul, korea, IMC, passing approximately FL140, we passed within about 300 ft of a flight of 2 aircraft. TCASII sounded to descend and we descended sharply. In about 2 seconds, the TCASII sounded to resume climb, which we did. The 2 aircraft were observed on the TCASII screen to be at 200 ft and 300 ft, respectively, above us. We queried ATC and they stated there was VFR traffic in that area but ATC would not tell us who they were. We advised korea ATC of the near miss. Flight progressed normally on to narita. Route G597 is a 1-WAY routing for departures leaving seoul. Quite often, aircraft appear on this route on the TCASII without elevation readouts. The route needs to be dedicated to civil departure aircraft or else another route needs to be specified. The closure rate in this near miss was around 800 KTS and to miss at 300 ft is terrible! Supplemental information from acn 377669: during climb out on G597, departure control gave us a TA, 'traffic at 10 O'clock.' there was an area of numerous targets at approximately 20 NM. Due to the density of targets, their altitudes could not be delineated. About 20 seconds later, a target was read at approximately 10 mi and 1200 ft above at 11 O'clock. I suggested to PF, 'we should level off briefly.' he started to decrease the climb. ATC called again, 'traffic at 11 O'clock.' TCASII alert, 'descend!' the pilot commenced the avoidance maneuver. Initial descent rate 1500 FPM down. The traffic was observed on TCASII screen at +200/+300 (2 targets) 200 ft and 300 ft above us. We were just entering an area of clouds and never saw the traffic. The horizontal separation was not clear on the screen, possibly 0- 400 yards off the left side. Total time from first warning by ATC till end of incident was 1 min or less. Center: 'who was the traffic we just missed?' the answer was, 'it was VFR traffic not in their control.' in 30 yrs of flying, this was perhaps the 'closest call' I've ever had! VFR traffic flying uncontrolled on an airway will eventually cause disastrous results! Supplemental information from acn 377470: climbing out of sel, IMC, passing approximately 14000 ft, we passed within about 300 ft of a flight of 2 aircraft. TCASII sounded to descend and the pilots descended. In about 2 seconds, the TCASII sounded to resume climb, which the pilots did. The 2 aircraft were observed on the TCASII screen to be at 200 ft and 300 ft, respectively, above us. The only way to prevent this type of incident from happening again, is to restrict VFR military traffic from flying near the airways.

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Original NASA ASRS Text

Title: A B747-100 DEPARTING OUT OF SEOUL, KOREA, HAS AN NMAC WITH MIL FIGHTER.

Narrative: AT XX28Z CLBING OUT OF SEOUL, KOREA, IMC, PASSING APPROX FL140, WE PASSED WITHIN ABOUT 300 FT OF A FLT OF 2 ACFT. TCASII SOUNDED TO DSND AND WE DSNDED SHARPLY. IN ABOUT 2 SECONDS, THE TCASII SOUNDED TO RESUME CLB, WHICH WE DID. THE 2 ACFT WERE OBSERVED ON THE TCASII SCREEN TO BE AT 200 FT AND 300 FT, RESPECTIVELY, ABOVE US. WE QUERIED ATC AND THEY STATED THERE WAS VFR TFC IN THAT AREA BUT ATC WOULD NOT TELL US WHO THEY WERE. WE ADVISED KOREA ATC OF THE NEAR MISS. FLT PROGRESSED NORMALLY ON TO NARITA. RTE G597 IS A 1-WAY ROUTING FOR DEPS LEAVING SEOUL. QUITE OFTEN, ACFT APPEAR ON THIS RTE ON THE TCASII WITHOUT ELEVATION READOUTS. THE RTE NEEDS TO BE DEDICATED TO CIVIL DEP ACFT OR ELSE ANOTHER RTE NEEDS TO BE SPECIFIED. THE CLOSURE RATE IN THIS NEAR MISS WAS AROUND 800 KTS AND TO MISS AT 300 FT IS TERRIBLE! SUPPLEMENTAL INFO FROM ACN 377669: DURING CLBOUT ON G597, DEP CTL GAVE US A TA, 'TFC AT 10 O'CLOCK.' THERE WAS AN AREA OF NUMEROUS TARGETS AT APPROX 20 NM. DUE TO THE DENSITY OF TARGETS, THEIR ALTS COULD NOT BE DELINEATED. ABOUT 20 SECONDS LATER, A TARGET WAS READ AT APPROX 10 MI AND 1200 FT ABOVE AT 11 O'CLOCK. I SUGGESTED TO PF, 'WE SHOULD LEVEL OFF BRIEFLY.' HE STARTED TO DECREASE THE CLB. ATC CALLED AGAIN, 'TFC AT 11 O'CLOCK.' TCASII ALERT, 'DSND!' THE PLT COMMENCED THE AVOIDANCE MANEUVER. INITIAL DSCNT RATE 1500 FPM DOWN. THE TFC WAS OBSERVED ON TCASII SCREEN AT +200/+300 (2 TARGETS) 200 FT AND 300 FT ABOVE US. WE WERE JUST ENTERING AN AREA OF CLOUDS AND NEVER SAW THE TFC. THE HORIZ SEPARATION WAS NOT CLR ON THE SCREEN, POSSIBLY 0- 400 YARDS OFF THE L SIDE. TOTAL TIME FROM FIRST WARNING BY ATC TILL END OF INCIDENT WAS 1 MIN OR LESS. CTR: 'WHO WAS THE TFC WE JUST MISSED?' THE ANSWER WAS, 'IT WAS VFR TFC NOT IN THEIR CTL.' IN 30 YRS OF FLYING, THIS WAS PERHAPS THE 'CLOSEST CALL' I'VE EVER HAD! VFR TFC FLYING UNCTLED ON AN AIRWAY WILL EVENTUALLY CAUSE DISASTROUS RESULTS! SUPPLEMENTAL INFO FROM ACN 377470: CLBING OUT OF SEL, IMC, PASSING APPROX 14000 FT, WE PASSED WITHIN ABOUT 300 FT OF A FLT OF 2 ACFT. TCASII SOUNDED TO DSND AND THE PLTS DSNDED. IN ABOUT 2 SECONDS, THE TCASII SOUNDED TO RESUME CLB, WHICH THE PLTS DID. THE 2 ACFT WERE OBSERVED ON THE TCASII SCREEN TO BE AT 200 FT AND 300 FT, RESPECTIVELY, ABOVE US. THE ONLY WAY TO PREVENT THIS TYPE OF INCIDENT FROM HAPPENING AGAIN, IS TO RESTRICT VFR MIL TFC FROM FLYING NEAR THE AIRWAYS.

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.