NMAC.

Narrative

ON SEP/SAT/94 AT XX15 AM; A ACR 737 AND CITATION 650; PERFORMED EVASIVE MANEUVERS IN RESPONSE TO A TCASII ADVISORY AND VISUAL OBSERVATION BY BOTH FLCS. THE FOLLOWING DESCRIPTION IS BASED ON A COCKPIT VOICE RECORDER TRANSCRIPT AND CONVERSATIONS WITH ALL PARTIES INVOLVED. THE 737 DEPARTED IAH AND FLEW RADAR VECTORS TO INTERCEPT J-86 FROM HOUSTON TO AUSTIN WITH ALBUQUERQUE AS THE DEST. THE 737 CREW RPTED LATER THAT THEY WERE CLBING THROUGH 11000 FT ON A 272 DEG COURSE WHEN THEY ESTABLISHED VISUAL CONTACT WITH THE CITATION 650. AT THAT MOMENT; THE CITATION WAS DSNDING THROUGH 12600 FT AT A RATE OF 2500 FPM; ON A HDG OF 160-170 DEGS; APPROX 5 MI N-NW OF THE 737. THE CITATION CANCELED IFR WITH ZHU WHILE DSNDING THROUGH 17000 FT AND WAS HANDED OFF TO HOUSTON APCH FOR FLT FOLLOWING. THE EVASIVE ACTION OCCURRED BEFORE IT WAS POSSIBLE TO ESTABLISH RADIO CONTACT WITH HOU APCH BY THE CITATION CREW; ALTHOUGH THE CITATION CREW DID RECEIVE ALL XMISSIONS ON THE APCH FREQ. THE SIC; FLYING THE CITATION FROM THE L SEAT; FIRST NOTICED THE TCASII TARGET AND STATED TO THE PIC; WHO WAS ATTEMPTING TO CONTACT APCH CTL; 'WE HAVE A PROB.' HE THEN INDICATED TO THE PIC THE VISUAL TCASII DISPLAY OF THE MERGING 737 AT AN ALT 2500 FT BELOW AND CLBING TO THE L OF THE CITATION AT A RANGE OF ABOUT 3 MI; AND STARTED A SHALLOW R TURN. THE TCASII TA OCCURRED WITHIN 1 OR 2 SECONDS LATER. THE PIC RESPONDED BY MAKING VISUAL CONTACT WITH THE 737 THROUGH THE L FRONT WINDSHIELD THEN ASKED THE SIC TO 'GO VISUAL' (MEANING: STOP MANEUVERING THE ACFT BY OBSERVING THE TCASII AND LOOK THROUGH THE WINDSHIELD); POINTED THE TFC OUT TO THE SIC; QUESTIONED THE TURN TO THE R AND THEN ORDERED A TURN TO THE L. THE R SIDE OF THE 737 WAS VISIBLE TO THE CITATION CREW. THE SIC ACKNOWLEDGED VISUAL CONTACT; DISCONNECTED THE AUTOPLT AND INCREASED THE BANK TO THE R. THE INCREASE IN THE RATE OF TURN BLOCKED THE TFC FROM THE PIC'S VIEW AND HE DID NOT BELIEVE IT WAS APPROPRIATE TO TAKE THE CTLS AT THAT POINT. AT THAT MOMENT THE TCASII COMMANDED; 'CLB; CLB; CLB.' THE SIC REQUESTED THE PIC TO SET THE TCASII SELECTOR TO THE TA POS AND INCREASED THE RATE OF DSCNT AND RATE OF TURN TO THE R. THE PIC THEN MONITORED THE TCASII DISPLAY AND UPDATED THE SIC WITH HIS TCASII OBSERVATIONS; INCLUDING THE FACT THAT THE 737 WAS SUDDENLY DSNDING INSTEAD OF CLBING. THE NEXT VISUAL CONTACT WITH THE 737 BY THE PIC OCCURRED NEAR THE BOTTOM OF THE DSCNT ABOUT 8000 FT MSL. THE 2 ACFT WERE DIVERGING FROM A PARALLEL COURSE WITHIN 500 TO 600 FT HORIZ SEPARATION AND 100 FT VERT SEPARATION. USING 20/20 HINDSIGHT; IT IS OBVIOUS THAT THIS INCIDENT WOULD HAVE BEEN AVOIDED IF THE CITATION CREW HAD FOLLOWED THE TCASII RA AND THE PIC'S ORDER TO MAKE A TURN TO THE L. THE PIC SHOULD HAVE TAKEN THE CTLS BEFORE THE 737 WAS BLOCKED FROM HIS VIEW. IT IS IMPORTANT TO NOTE THAT THE VISUAL SCENARIO OBSERVED BY THE CITATION PLTS CAUSED AN OVERWHELMING IMPULSE TO DSND INSTEAD OF CLB. CONSIDER THIS FACTS: THE 737 WAS CLBING; THE CITATION WAS DSNDING; AND NEARLY PERPENDICULAR TO THEIR RESPECTIVE COURSES. AT THE MOMENT WHEN THE CITATION CREW OBTAINED VISUAL CONTACT WITH THE 737; THE 2 ACFT WERE WITHIN 1500 FT VERT SEPARATION. IT WOULD HAVE RESULTED IN THE CITATION STOPPING ITS DSCNT AND CLBING INTO THE FLT PATH OF THE 737; UNLESS A L TURN TO PASS BEHIND THE 737 WAS EXECUTED QUICKLY. IT SHOULD ALSO BE NOTED THAT THE DECISION TO CANCEL IFR AND MAKE A VISUAL APCH INTO THE UNCTLED ARPT WAS BASED ON YRS OF TFC PROBS EXPERIENCED WITH THE PUBLISHED ARR PROC. THE IFR ARR REQUIRES ACFT LNDG AT THE HOUSTON SATELLITE ARPTS TO DSND INTO AIRSPACE FREQUENTLY CONGESTED WITH VFR TFC. THE CITATION CREW HAS EXPERIENCED COUNTLESS TFC CONFLICTS AND EVASIVE MANEUVERS RESULTING FROM EXTENDED FLT AT LOW ALTS ON THE IFR ARR. TELEPHONE DISCUSSIONS AND MEETINGS WITH ATC MGMNT HAVE NOT RESOLVED THIS PROB.