Narrative:

An mdt and an large transport were noticed at our (air carrier X) 2 O'clock and 3 O'clock position and then showed up on our TCASII (TA mode only) at 10 mi. The mdt showed at 13700 ft MSL and the large transport was at 13200 ft MSL. ATC reported the traffic to us at this time. The controller told us they were VFR and wasn't aware of what the large transport and mdt traffic were doing. Captain stated traffic was in sight. The large transport stated he had us in sight. The controller told us to turn 20 degrees left, which still didn't help the situation. Captain called the controller to let him know this would not work and was a safety factor. The controller told us to take whatever heading was necessary. We then turned right towards the direction of the large transport's tail so as to pass behind it. Both aircraft now began a circling turn to the right. They crossed our flight path in front. They continued their circle and were heading directly at us still at their same altitudes. We eventually hit the wake turbulence from the large transport. The flight attendant was injured. Captain instructed me to descend. We vacated 13000 ft and descended to between 12600 ft and 12500 ft. The large transport passed over us and slightly behind. Supplemental information from acn 248223: during a mode south, 2 aircraft right&D mission, our large transport was traversing inbound on the acy 242 degree radial at approximately 25 DME at 13200 ft MSL and passing beneath the mdt which was inbound at 13700 ft MSL. Air carrier X was reported at our 7-8 O'clock position, 7-10 mi and 13000 ft MSL by ATC. We had and reported visual contact with this aircraft to ATC as he did with us. Subsequently, conversations were overheard between this aircraft and ATC, the substance of which was that air carrier X would maneuver to pass behind us. Later during our course reversal over acy to start the next outbound run, an unidented aircraft was heard to say 'get us away from them.' the mission was completed without further incident. Subsequent to the flight it was learned that air carrier X had maneuvered violently to avoid us and in so doing injured a cabin attendant.

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Original NASA ASRS Text

Title: ACR X TCASII TA WITH VFR LGT AND MDT EVASIVE ACTION TAKEN ENCOUNTERED WAKE TURB. FLT ATTENDANT INJURED. SEE AND AVOID CONCEPT.

Narrative: AN MDT AND AN LGT WERE NOTICED AT OUR (ACR X) 2 O'CLOCK AND 3 O'CLOCK POS AND THEN SHOWED UP ON OUR TCASII (TA MODE ONLY) AT 10 MI. THE MDT SHOWED AT 13700 FT MSL AND THE LGT WAS AT 13200 FT MSL. ATC RPTED THE TFC TO US AT THIS TIME. THE CTLR TOLD US THEY WERE VFR AND WASN'T AWARE OF WHAT THE LGT AND MDT TFC WERE DOING. CAPT STATED TFC WAS IN SIGHT. THE LGT STATED HE HAD US IN SIGHT. THE CTLR TOLD US TO TURN 20 DEGS L, WHICH STILL DIDN'T HELP THE SIT. CAPT CALLED THE CTLR TO LET HIM KNOW THIS WOULD NOT WORK AND WAS A SAFETY FACTOR. THE CTLR TOLD US TO TAKE WHATEVER HDG WAS NECESSARY. WE THEN TURNED R TOWARDS THE DIRECTION OF THE LGT'S TAIL SO AS TO PASS BEHIND IT. BOTH ACFT NOW BEGAN A CIRCLING TURN TO THE R. THEY CROSSED OUR FLT PATH IN FRONT. THEY CONTINUED THEIR CIRCLE AND WERE HDG DIRECTLY AT US STILL AT THEIR SAME ALTS. WE EVENTUALLY HIT THE WAKE TURB FROM THE LGT. THE FLT ATTENDANT WAS INJURED. CAPT INSTRUCTED ME TO DSND. WE VACATED 13000 FT AND DSNDED TO BTWN 12600 FT AND 12500 FT. THE LGT PASSED OVER US AND SLIGHTLY BEHIND. SUPPLEMENTAL INFORMATION FROM ACN 248223: DURING A MODE S, 2 ACFT R&D MISSION, OUR LGT WAS TRAVERSING INBOUND ON THE ACY 242 DEG RADIAL AT APPROX 25 DME AT 13200 FT MSL AND PASSING BENEATH THE MDT WHICH WAS INBOUND AT 13700 FT MSL. ACR X WAS RPTED AT OUR 7-8 O'CLOCK POS, 7-10 MI AND 13000 FT MSL BY ATC. WE HAD AND RPTED VISUAL CONTACT WITH THIS ACFT TO ATC AS HE DID WITH US. SUBSEQUENTLY, CONVERSATIONS WERE OVERHEARD BTWN THIS ACFT AND ATC, THE SUBSTANCE OF WHICH WAS THAT ACR X WOULD MANEUVER TO PASS BEHIND US. LATER DURING OUR COURSE REVERSAL OVER ACY TO START THE NEXT OUTBOUND RUN, AN UNIDENTED ACFT WAS HEARD TO SAY 'GET US AWAY FROM THEM.' THE MISSION WAS COMPLETED WITHOUT FURTHER INCIDENT. SUBSEQUENT TO THE FLT IT WAS LEARNED THAT ACR X HAD MANEUVERED VIOLENTLY TO AVOID US AND IN SO DOING INJURED A CABIN ATTENDANT.

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.