Narrative:

The problem arose during a runway 13L departure from boeing field when the departure controller pointed out another aircraft, an air carrier 767 climbing out of seatac airport sbound, and asked us if we had visual contact. We did and so advised. The controller then asked us to maintain visual separation with that aircraft during the climb but then unexpectedly and immediately gave us a heading that would put us on a perfect head-on collision course with that aircraft. The altitudes and climb rates of both aircraft were very similar. Our desired route was wbound and the air carrier 767 was turning eastbound. The altitude and relative position of the 767 was monitored on the TCASII display. I could see a conflict developing as we turned to the requested heading. The FAA flight test pilot was the PF at the time through the autoplt. I then assumed manual control first officer the airplane and increased the rate of climb several thousand FPM so as to pass above the 767. Shortly after that, a TA was issued by TCASII. Within a few seconds a preventative RA was issued, which came out as an aural warning 'monitor vertical speed.' the corresponding pitch limit indication on the primary flight display (pfd) to avoid the other aircraft was to maintain a pitch attitude no lower than about 15 to 20 degrees nose up. The RA did not require any additional maneuvering or any deviation from our clearance. We had to make a very rapid climb to our assigned altitude of 9000 ft MSL to avoid the 767. I'm a little uncertain what the crew of the 767 were told about the separation given to them. If they were also maintaining visual separation, then perhaps they were also expediting their climb to avoid us. I don't know. In the future, I won't be so quick to volunteer to do the visual separation function, especially when a conflict can be seen in the making. Does accepting responsibility for visual spn allow you to disregard subsequent radar vectors? Will ATC give the 2 aircraft involved the same 'maintain visual separation' clearance? ATC should not be providing vectors that create a risk of collision that the pilot then has to recover from. 2 aircraft both climbing and turning towards a head-on encounter make it difficult to judge what evasive action might be required to 'maintain visual separation.'

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Original NASA ASRS Text

Title: B-777 TCASII TA RA HAD NMAC WITH B-767. VISUAL SEPARATION USED SEE AND AVOID CONCEPT IN CLASS B AIRSPACE.

Narrative: THE PROB AROSE DURING A RWY 13L DEP FROM BOEING FIELD WHEN THE DEP CTLR POINTED OUT ANOTHER ACFT, AN ACR 767 CLBING OUT OF SEATAC ARPT SBOUND, AND ASKED US IF WE HAD VISUAL CONTACT. WE DID AND SO ADVISED. THE CTLR THEN ASKED US TO MAINTAIN VISUAL SEPARATION WITH THAT ACFT DURING THE CLB BUT THEN UNEXPECTEDLY AND IMMEDIATELY GAVE US A HDG THAT WOULD PUT US ON A PERFECT HEAD-ON COLLISION COURSE WITH THAT ACFT. THE ALTS AND CLB RATES OF BOTH ACFT WERE VERY SIMILAR. OUR DESIRED RTE WAS WBOUND AND THE ACR 767 WAS TURNING EBOUND. THE ALT AND RELATIVE POS OF THE 767 WAS MONITORED ON THE TCASII DISPLAY. I COULD SEE A CONFLICT DEVELOPING AS WE TURNED TO THE REQUESTED HDG. THE FAA FLT TEST PLT WAS THE PF AT THE TIME THROUGH THE AUTOPLT. I THEN ASSUMED MANUAL CTL FO THE AIRPLANE AND INCREASED THE RATE OF CLB SEVERAL THOUSAND FPM SO AS TO PASS ABOVE THE 767. SHORTLY AFTER THAT, A TA WAS ISSUED BY TCASII. WITHIN A FEW SECONDS A PREVENTATIVE RA WAS ISSUED, WHICH CAME OUT AS AN AURAL WARNING 'MONITOR VERT SPD.' THE CORRESPONDING PITCH LIMIT INDICATION ON THE PRIMARY FLT DISPLAY (PFD) TO AVOID THE OTHER ACFT WAS TO MAINTAIN A PITCH ATTITUDE NO LOWER THAN ABOUT 15 TO 20 DEGS NOSE UP. THE RA DID NOT REQUIRE ANY ADDITIONAL MANEUVERING OR ANY DEV FROM OUR CLRNC. WE HAD TO MAKE A VERY RAPID CLB TO OUR ASSIGNED ALT OF 9000 FT MSL TO AVOID THE 767. I'M A LITTLE UNCERTAIN WHAT THE CREW OF THE 767 WERE TOLD ABOUT THE SEPARATION GIVEN TO THEM. IF THEY WERE ALSO MAINTAINING VISUAL SEPARATION, THEN PERHAPS THEY WERE ALSO EXPEDITING THEIR CLB TO AVOID US. I DON'T KNOW. IN THE FUTURE, I WON'T BE SO QUICK TO VOLUNTEER TO DO THE VISUAL SEPARATION FUNCTION, ESPECIALLY WHEN A CONFLICT CAN BE SEEN IN THE MAKING. DOES ACCEPTING RESPONSIBILITY FOR VISUAL SPN ALLOW YOU TO DISREGARD SUBSEQUENT RADAR VECTORS? WILL ATC GIVE THE 2 ACFT INVOLVED THE SAME 'MAINTAIN VISUAL SEPARATION' CLRNC? ATC SHOULD NOT BE PROVIDING VECTORS THAT CREATE A RISK OF COLLISION THAT THE PLT THEN HAS TO RECOVER FROM. 2 ACFT BOTH CLBING AND TURNING TOWARDS A HEAD-ON ENCOUNTER MAKE IT DIFFICULT TO JUDGE WHAT EVASIVE ACTION MIGHT BE REQUIRED TO 'MAINTAIN VISUAL SEPARATION.'

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.