Narrative:

Our cessna cardinal was cruising northeast on autoplt at 7000 ft MSL, about 20 mi southwest of centralia VOR. We were in contact with a kansas city ARTCC controller. About XA15 zulu, our controller called to inform me of traffic 'at your 10 O'clock position, 7 mi, sebound at 6000 ft, a KC135. He'll be climbing.' before the controller finished speaking, my wife saw the tanker, and I immediately replied to center that we had visual contact. The tanker was easy to see, painting a black exhaust trail against a lower overcast layer. The center controller reported our type, direction, position, and altitude to the military pilot. Almost immediately, the military pilot reported 'I have the traffic,' and center responded by clearing him to climb and maintain 11000 ft. The controller then called to inform me of what I had just heard, and he added 'caution, wake turbulence.' at this point, the KC135 was about 4-5 mi at my 10 O'clock position, 1000 ft below, and I saw him start his climb. Our flight paths were almost perpendicular to each other, with the angle perhaps slightly greater than 90 degrees. As we continued, the other aircraft remained at our 10 O'clock position as he rose toward our altitude. Soon it become apparent to me that our 2 planes were proceeding toward the same point in space. The tanker was less than 2 mi away and looming large when I punched the autoplt disconnect and began a climbing left turn while keeping the other plane in sight. I had climbed about 150 ft and had altered course about 45 degrees, when the KC135 crossed our nose. I estimate the horizontal separation was 500 ft or less. The vertical separation was difficult to judge, because of our flight attitude, but I believe the tanker was at or slightly below our altitude (about 7150 ft MSL) at that instant. In just 2 or 3 seconds, as I maintained the climb and the altered heading, we crossed above the KC135's wake, feeling 2 distinct, but light bumps. We were just above 7200 ft MSL. I resumed our planned altitude and heading. The incident was over. The kansas city controller reported 'traffic no factor,' and I acknowledged and replied that I didn't believe the military pilot had actually seen us. The tanker pilot interjected 'that's why I came left.' I suspect he might have 'seen' us electronically from 5 mi away, but didn't actually eyeball us until much closer, and I began my maneuver. Our cardinal is blue-tinted white, and we were flying beneath high stratus that surely provided less-than-ideal contrast. In my opinion, no one involved in this incident committed any violations, but it was a case where the pilots might have been perfectly legal and perfectly dead. The controller handled the traffic by the book. When both pilots claimed visual contact, the onus was upon us to see-and-avoid. We did so, and life goes on. Nevertheless, I would strongly recommend these changes in traffic control procedures to reduce the likelihood of incidents such as this: when a brief delay in climb or descent instructions will avoid creation of a potential traffic conflict, controllers should exercise that delay, no matter if the pilots claim visual contact. This practice would seem especially appropriate when speeds and closing rates are high. Controllers should heed the capabilities of the respective aircraft when creating a potentially strong encounter with wake turbulence. Recitation of the 'caution, wake turbulence' mantra might satisfy the regulations, but it does little to enhance safety when a light plane pilot has no real opportunity to prevent wake encounter short of independent evasive action. If a controller must send a light plane across or near the wake of a large aircraft, a redirect of the light plane would be the safer choice.

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Original NASA ASRS Text

Title: CRUISING IFR C177 EXPERIENCED CONFLICT WITH CLBING KC135 UTILIZING VISUAL SEPARATION.

Narrative: OUR CESSNA CARDINAL WAS CRUISING NE ON AUTOPLT AT 7000 FT MSL, ABOUT 20 MI SW OF CENTRALIA VOR. WE WERE IN CONTACT WITH A KANSAS CITY ARTCC CTLR. ABOUT XA15 ZULU, OUR CTLR CALLED TO INFORM ME OF TFC 'AT YOUR 10 O'CLOCK POS, 7 MI, SEBOUND AT 6000 FT, A KC135. HE'LL BE CLBING.' BEFORE THE CTLR FINISHED SPEAKING, MY WIFE SAW THE TANKER, AND I IMMEDIATELY REPLIED TO CTR THAT WE HAD VISUAL CONTACT. THE TANKER WAS EASY TO SEE, PAINTING A BLACK EXHAUST TRAIL AGAINST A LOWER OVCST LAYER. THE CTR CTLR RPTED OUR TYPE, DIRECTION, POS, AND ALT TO THE MIL PLT. ALMOST IMMEDIATELY, THE MIL PLT RPTED 'I HAVE THE TFC,' AND CTR RESPONDED BY CLRING HIM TO CLB AND MAINTAIN 11000 FT. THE CTLR THEN CALLED TO INFORM ME OF WHAT I HAD JUST HEARD, AND HE ADDED 'CAUTION, WAKE TURB.' AT THIS POINT, THE KC135 WAS ABOUT 4-5 MI AT MY 10 O'CLOCK POS, 1000 FT BELOW, AND I SAW HIM START HIS CLB. OUR FLT PATHS WERE ALMOST PERPENDICULAR TO EACH OTHER, WITH THE ANGLE PERHAPS SLIGHTLY GREATER THAN 90 DEGS. AS WE CONTINUED, THE OTHER ACFT REMAINED AT OUR 10 O'CLOCK POS AS HE ROSE TOWARD OUR ALT. SOON IT BECOME APPARENT TO ME THAT OUR 2 PLANES WERE PROCEEDING TOWARD THE SAME POINT IN SPACE. THE TANKER WAS LESS THAN 2 MI AWAY AND LOOMING LARGE WHEN I PUNCHED THE AUTOPLT DISCONNECT AND BEGAN A CLBING L TURN WHILE KEEPING THE OTHER PLANE IN SIGHT. I HAD CLBED ABOUT 150 FT AND HAD ALTERED COURSE ABOUT 45 DEGS, WHEN THE KC135 CROSSED OUR NOSE. I ESTIMATE THE HORIZ SEPARATION WAS 500 FT OR LESS. THE VERT SEPARATION WAS DIFFICULT TO JUDGE, BECAUSE OF OUR FLT ATTITUDE, BUT I BELIEVE THE TANKER WAS AT OR SLIGHTLY BELOW OUR ALT (ABOUT 7150 FT MSL) AT THAT INSTANT. IN JUST 2 OR 3 SECONDS, AS I MAINTAINED THE CLB AND THE ALTERED HDG, WE CROSSED ABOVE THE KC135'S WAKE, FEELING 2 DISTINCT, BUT LIGHT BUMPS. WE WERE JUST ABOVE 7200 FT MSL. I RESUMED OUR PLANNED ALT AND HDG. THE INCIDENT WAS OVER. THE KANSAS CITY CTLR RPTED 'TFC NO FACTOR,' AND I ACKNOWLEDGED AND REPLIED THAT I DIDN'T BELIEVE THE MIL PLT HAD ACTUALLY SEEN US. THE TANKER PLT INTERJECTED 'THAT'S WHY I CAME L.' I SUSPECT HE MIGHT HAVE 'SEEN' US ELECTRONICALLY FROM 5 MI AWAY, BUT DIDN'T ACTUALLY EYEBALL US UNTIL MUCH CLOSER, AND I BEGAN MY MANEUVER. OUR CARDINAL IS BLUE-TINTED WHITE, AND WE WERE FLYING BENEATH HIGH STRATUS THAT SURELY PROVIDED LESS-THAN-IDEAL CONTRAST. IN MY OPINION, NO ONE INVOLVED IN THIS INCIDENT COMMITTED ANY VIOLATIONS, BUT IT WAS A CASE WHERE THE PLTS MIGHT HAVE BEEN PERFECTLY LEGAL AND PERFECTLY DEAD. THE CTLR HANDLED THE TFC BY THE BOOK. WHEN BOTH PLTS CLAIMED VISUAL CONTACT, THE ONUS WAS UPON US TO SEE-AND-AVOID. WE DID SO, AND LIFE GOES ON. NEVERTHELESS, I WOULD STRONGLY RECOMMEND THESE CHANGES IN TFC CTL PROCS TO REDUCE THE LIKELIHOOD OF INCIDENTS SUCH AS THIS: WHEN A BRIEF DELAY IN CLB OR DSCNT INSTRUCTIONS WILL AVOID CREATION OF A POTENTIAL TFC CONFLICT, CTLRS SHOULD EXERCISE THAT DELAY, NO MATTER IF THE PLTS CLAIM VISUAL CONTACT. THIS PRACTICE WOULD SEEM ESPECIALLY APPROPRIATE WHEN SPDS AND CLOSING RATES ARE HIGH. CTLRS SHOULD HEED THE CAPABILITIES OF THE RESPECTIVE ACFT WHEN CREATING A POTENTIALLY STRONG ENCOUNTER WITH WAKE TURB. RECITATION OF THE 'CAUTION, WAKE TURB' MANTRA MIGHT SATISFY THE REGS, BUT IT DOES LITTLE TO ENHANCE SAFETY WHEN A LIGHT PLANE PLT HAS NO REAL OPPORTUNITY TO PREVENT WAKE ENCOUNTER SHORT OF INDEPENDENT EVASIVE ACTION. IF A CTLR MUST SEND A LIGHT PLANE ACROSS OR NEAR THE WAKE OF A LARGE ACFT, A REDIRECT OF THE LIGHT PLANE WOULD BE THE SAFER CHOICE.

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.