Narrative:

On sep/sat/94 at XX15 am, a air carrier 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 destination. The 737 crew reported later that they were climbing through 11000 ft on a 272 degree course when they established visual contact with the citation 650. At that moment, the citation was descending through 12600 ft at a rate of 2500 FPM, on a heading of 160-170 degrees, approximately 5 mi n-nw of the 737. The citation canceled IFR with ZHU while descending through 17000 ft and was handed off to houston approach for flight following. The evasive action occurred before it was possible to establish radio contact with hou approach by the citation crew, although the citation crew did receive all xmissions on the approach frequency. The sic, flying the citation from the left seat, first noticed the TCASII target and stated to the PIC, who was attempting to contact approach control, 'we have a problem.' he then indicated to the PIC the visual TCASII display of the merging 737 at an altitude 2500 ft below and climbing to the left of the citation at a range of about 3 mi, and started a shallow right turn. The TCASII TA occurred within 1 or 2 seconds later. The PIC responded by making visual contact with the 737 through the left front windshield then asked the sic to 'go visual' (meaning: stop maneuvering the aircraft by observing the TCASII and look through the windshield), pointed the traffic out to the sic, questioned the turn to the right and then ordered a turn to the left. The right side of the 737 was visible to the citation crew. The sic acknowledged visual contact, disconnected the autoplt and increased the bank to the right. The increase in the rate of turn blocked the traffic from the PIC's view and he did not believe it was appropriate to take the controls at that point. At that moment the TCASII commanded, 'climb, climb, climb.' the sic requested the PIC to set the TCASII selector to the TA position and increased the rate of descent and rate of turn to the right. The PIC then monitored the TCASII display and updated the sic with his TCASII observations, including the fact that the 737 was suddenly descending instead of climbing. The next visual contact with the 737 by the PIC occurred near the bottom of the descent about 8000 ft MSL. The 2 aircraft were diverging from a parallel course within 500 to 600 ft horizontal separation and 100 ft vertical 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 left. The PIC should have taken the controls before the 737 was blocked from his view. It is important to note that the visual scenario observed by the citation pilots caused an overwhelming impulse to descend instead of climb. Consider this facts: the 737 was climbing, the citation was descending, and nearly perpendicular to their respective courses. At the moment when the citation crew obtained visual contact with the 737, the 2 aircraft were within 1500 ft vertical separation. It would have resulted in the citation stopping its descent and climbing into the flight path of the 737, unless a left turn to pass behind the 737 was executed quickly. It should also be noted that the decision to cancel IFR and make a visual approach into the uncontrolled airport was based on yrs of traffic problems experienced with the published arrival procedure. The IFR arrival requires aircraft landing at the houston satellite airports to descend into airspace frequently congested with VFR traffic. The citation crew has experienced countless traffic conflicts and evasive maneuvers resulting from extended flight at low altitudes on the IFR arrival. Telephone discussions and meetings with ATC management have not resolved this problem.

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Original NASA ASRS Text

Title: 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.

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.