Narrative:

How the problem arose: aircraft #1 (mine) was northbound, tracking V-39 to gve VOR. Mc 032 at 5500 ft. Winds were forecast (and appeared) westerly near 20 KTS, so my magnetic heading was about 010 degrees. #1 was monitoring but not in contact with richmond approach 132.85 sector. Aircraft #2 apparently was nwbound, level above (or descending very slowly into) the same altitude, and either IFR or VFR advisories with ric approach. Courses crossed at near right angles. How the problem was discovered: #1 heard ric approach call traffic for #2 'at your 9 O'clock, 1 mi...heading north at 5500 ft' or words to that effect. After a short delay, I heard #2 inform ric approach that they had 'traffic in sight.' recognizing that my direction and altitude matched the ric description, I immediately began looking for #2 on my right (east) side, as I assumed traffic might be out of ric. I rolled my right wing up but was unable to locate #2. I then began looking behind and below me, under both wings. Still unable to locate traffic (I had no knowledge of #2's altitude), I returned to forward scan and immediately spotted #2 at my 1-2 O'clock position, roughly 1/3 mi ahead and above me +100-150 ft. Aircraft #2 appeared to be in near level flight on a near right angle crossing course. Given my heading and altitude (about 5600 ft, my mode C reads slightly low), I later concluded #2 was heading about 300 degrees (assuming a smaller wca) at an altitude of about 5750 ft. I would have expected level VFR crossing traffic at an even-plus altitude, yielding a 1000 ft separation. IFR would (should) have had better separation -- unless descending en route. (Possible but unlikely: there are mountains west of, and no public airfields anywhere near this location.) corrective actions needed: it probably took at least 3-4 seconds to assess and confirm a potential collision course (ie, constant angle of convergence), during which both aircraft continued to close rapidly. I went nose down, to immediately increase vertical separation, preparatory to a right turn to pass clear aft or, and give way to, aircraft #2. As I did so, and before my right turn was executed, #2 suddenly dived through my altitude while passing right to left (west) ahead of me, at a distance of not more than 250 yards. I rolled right (east) immediately and passed clear, aft of #2 at not more than 200 yards horizontal, and -200 ft vertical separation (#2 now below #1). Thereafter, I lost contact with #2 and heard nothing more on 132.85, from either #1 or ric. Human performance factors, perceptions, judgements, decisions and actions or inactions: given that #2 reported 'traffic in sight,' I was surprised the situation developed as it did. Under the circumstances, I was the burdened aircraft, required to give way. To do that, however, one must have the other aircraft in sight, which I did not (immediately). My first reaction on acquiring 32 so close by was surprise (and, perhaps, disbelief). This only increased response delay. Once I made contact and assessed the situation, I probably should have turned right, before dropping the nose, so as to signal clearly my sighting of #2 and intentions (to pass aft of it). Learnings: first, I learned how quickly 'proximity' can turn into 'near miss.' second, whenever operating near north or south (ie, across directional altitude demarcations), course/heading changes, for whatever reason, may create conflicts with other aircraft and/or confuse a radar controller. Once stabilized on track, it is important to hold course as steady as possible at the appropriate altitude. Third, when encountering conflicting traffic, it is important to hold course as steady as possible at the appropriate altitude. Third, when encountering conflicting traffic, it is important to maneuver so as to give clear indications of intended actions to the other aircraft. Delay or indecision only adds uncertainty -- and risk. Fourth, whenever reporting 'traffic in sight' it is important to remember that same may not be the case for the other aircraft. Right-of-way does not relieve one of responsibility to avoid incidents. I will make it a point to maneuver well clear, regardless. Finally, I have reviewed scan procedures. This was simply too close for comfort.

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Original NASA ASRS Text

Title: NMAC BTWN A C150 IN LEVEL FLT AT 5500 FT MSL NBOUND AND A C172 NWBOUND IN A SLOW DSCNT UNDER FLT FOLLOWING PROVISIONS. TA ISSUED TO C172 TO WHICH THE PLT RPTED THE C150 IN SIGHT.

Narrative: HOW THE PROB AROSE: ACFT #1 (MINE) WAS NBOUND, TRACKING V-39 TO GVE VOR. MC 032 AT 5500 FT. WINDS WERE FORECAST (AND APPEARED) WESTERLY NEAR 20 KTS, SO MY MAGNETIC HDG WAS ABOUT 010 DEGS. #1 WAS MONITORING BUT NOT IN CONTACT WITH RICHMOND APCH 132.85 SECTOR. ACFT #2 APPARENTLY WAS NWBOUND, LEVEL ABOVE (OR DSNDING VERY SLOWLY INTO) THE SAME ALT, AND EITHER IFR OR VFR ADVISORIES WITH RIC APCH. COURSES CROSSED AT NEAR R ANGLES. HOW THE PROB WAS DISCOVERED: #1 HEARD RIC APCH CALL TFC FOR #2 'AT YOUR 9 O'CLOCK, 1 MI...HDG N AT 5500 FT' OR WORDS TO THAT EFFECT. AFTER A SHORT DELAY, I HEARD #2 INFORM RIC APCH THAT THEY HAD 'TFC IN SIGHT.' RECOGNIZING THAT MY DIRECTION AND ALT MATCHED THE RIC DESCRIPTION, I IMMEDIATELY BEGAN LOOKING FOR #2 ON MY R (E) SIDE, AS I ASSUMED TFC MIGHT BE OUT OF RIC. I ROLLED MY R WING UP BUT WAS UNABLE TO LOCATE #2. I THEN BEGAN LOOKING BEHIND AND BELOW ME, UNDER BOTH WINGS. STILL UNABLE TO LOCATE TFC (I HAD NO KNOWLEDGE OF #2'S ALT), I RETURNED TO FORWARD SCAN AND IMMEDIATELY SPOTTED #2 AT MY 1-2 O'CLOCK POS, ROUGHLY 1/3 MI AHEAD AND ABOVE ME +100-150 FT. ACFT #2 APPEARED TO BE IN NEAR LEVEL FLT ON A NEAR R ANGLE XING COURSE. GIVEN MY HDG AND ALT (ABOUT 5600 FT, MY MODE C READS SLIGHTLY LOW), I LATER CONCLUDED #2 WAS HDG ABOUT 300 DEGS (ASSUMING A SMALLER WCA) AT AN ALT OF ABOUT 5750 FT. I WOULD HAVE EXPECTED LEVEL VFR XING TFC AT AN EVEN-PLUS ALT, YIELDING A 1000 FT SEPARATION. IFR WOULD (SHOULD) HAVE HAD BETTER SEPARATION -- UNLESS DSNDING ENRTE. (POSSIBLE BUT UNLIKELY: THERE ARE MOUNTAINS W OF, AND NO PUBLIC AIRFIELDS ANYWHERE NEAR THIS LOCATION.) CORRECTIVE ACTIONS NEEDED: IT PROBABLY TOOK AT LEAST 3-4 SECONDS TO ASSESS AND CONFIRM A POTENTIAL COLLISION COURSE (IE, CONSTANT ANGLE OF CONVERGENCE), DURING WHICH BOTH ACFT CONTINUED TO CLOSE RAPIDLY. I WENT NOSE DOWN, TO IMMEDIATELY INCREASE VERT SEPARATION, PREPARATORY TO A R TURN TO PASS CLR AFT OR, AND GIVE WAY TO, ACFT #2. AS I DID SO, AND BEFORE MY R TURN WAS EXECUTED, #2 SUDDENLY DIVED THROUGH MY ALT WHILE PASSING R TO L (W) AHEAD OF ME, AT A DISTANCE OF NOT MORE THAN 250 YARDS. I ROLLED R (E) IMMEDIATELY AND PASSED CLR, AFT OF #2 AT NOT MORE THAN 200 YARDS HORIZ, AND -200 FT VERT SEPARATION (#2 NOW BELOW #1). THEREAFTER, I LOST CONTACT WITH #2 AND HEARD NOTHING MORE ON 132.85, FROM EITHER #1 OR RIC. HUMAN PERFORMANCE FACTORS, PERCEPTIONS, JUDGEMENTS, DECISIONS AND ACTIONS OR INACTIONS: GIVEN THAT #2 RPTED 'TFC IN SIGHT,' I WAS SURPRISED THE SIT DEVELOPED AS IT DID. UNDER THE CIRCUMSTANCES, I WAS THE BURDENED ACFT, REQUIRED TO GIVE WAY. TO DO THAT, HOWEVER, ONE MUST HAVE THE OTHER ACFT IN SIGHT, WHICH I DID NOT (IMMEDIATELY). MY FIRST REACTION ON ACQUIRING 32 SO CLOSE BY WAS SURPRISE (AND, PERHAPS, DISBELIEF). THIS ONLY INCREASED RESPONSE DELAY. ONCE I MADE CONTACT AND ASSESSED THE SIT, I PROBABLY SHOULD HAVE TURNED R, BEFORE DROPPING THE NOSE, SO AS TO SIGNAL CLRLY MY SIGHTING OF #2 AND INTENTIONS (TO PASS AFT OF IT). LEARNINGS: FIRST, I LEARNED HOW QUICKLY 'PROX' CAN TURN INTO 'NEAR MISS.' SECOND, WHENEVER OPERATING NEAR N OR S (IE, ACROSS DIRECTIONAL ALT DEMARCATIONS), COURSE/HDG CHANGES, FOR WHATEVER REASON, MAY CREATE CONFLICTS WITH OTHER ACFT AND/OR CONFUSE A RADAR CTLR. ONCE STABILIZED ON TRACK, IT IS IMPORTANT TO HOLD COURSE AS STEADY AS POSSIBLE AT THE APPROPRIATE ALT. THIRD, WHEN ENCOUNTERING CONFLICTING TFC, IT IS IMPORTANT TO HOLD COURSE AS STEADY AS POSSIBLE AT THE APPROPRIATE ALT. THIRD, WHEN ENCOUNTERING CONFLICTING TFC, IT IS IMPORTANT TO MANEUVER SO AS TO GIVE CLR INDICATIONS OF INTENDED ACTIONS TO THE OTHER ACFT. DELAY OR INDECISION ONLY ADDS UNCERTAINTY -- AND RISK. FOURTH, WHENEVER RPTING 'TFC IN SIGHT' IT IS IMPORTANT TO REMEMBER THAT SAME MAY NOT BE THE CASE FOR THE OTHER ACFT. RIGHT-OF-WAY DOES NOT RELIEVE ONE OF RESPONSIBILITY TO AVOID INCIDENTS. I WILL MAKE IT A POINT TO MANEUVER WELL CLR, REGARDLESS. FINALLY, I HAVE REVIEWED SCAN PROCS. THIS WAS SIMPLY TOO CLOSE FOR COMFORT.

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.