Narrative:

We were letting down in a gradual descent to 11000. Off airways cleared direct to vulcan VOR. Pilot in jumpseat reported an aircraft up ahead doing aerobatics. I saw a tandem seat straight wing foreign jet trainer zoom straight through 12000, pull through the top of a loop and dive straight down to the deck and disappear under the nose. We got a TA with no altitude at 12 O'clock. I also reported the aircraft to ZTL. I held course and altitude because I didn't know what he was going to do next. He then reappeared at 12:30 O'clock zooming straight up. I grabbed the controls, disconnected the autoplt and rolled a 30 degree bank to the left. As I lost sight of him he was zooming straight through our altitude. Intruder was squawking 1200, mode C off. No clearing turns, and may have been supersonic on the dives. TCASII has no defense for this. No injuries. 1 flight attendant landed in a passenger's lap. Everyone else was seated, seat belt sign was off. My evasive maneuver was rapid, but a coordinated turn. I used to be an aerobatic instructor, too. On the ground at bhm (our destination) the supervisor at ZTL told me the pilot of the jet had immediately landed at alberville, al, and phoned the center. He idented himself as (pilot name) (phone number). He was flying from the back seat with a student in the front. His aircraft was MTR. There are many excellent pilots who enjoy aerobatics and fly responsibly and safely. Other aircraft pilot is not one of them.

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Original NASA ASRS Text

Title: FLC OF AN MLG ACR ACFT TOOK EVASIVE ACTION BY MAKING AN ABRUPT TURN TO AVOID AN MTR ACFT DOING ACROBATICS.

Narrative: WE WERE LETTING DOWN IN A GRADUAL DSCNT TO 11000. OFF AIRWAYS CLRED DIRECT TO VULCAN VOR. PLT IN JUMPSEAT RPTED AN ACFT UP AHEAD DOING AEROBATICS. I SAW A TANDEM SEAT STRAIGHT WING FOREIGN JET TRAINER ZOOM STRAIGHT THROUGH 12000, PULL THROUGH THE TOP OF A LOOP AND DIVE STRAIGHT DOWN TO THE DECK AND DISAPPEAR UNDER THE NOSE. WE GOT A TA WITH NO ALT AT 12 O'CLOCK. I ALSO RPTED THE ACFT TO ZTL. I HELD COURSE AND ALT BECAUSE I DIDN'T KNOW WHAT HE WAS GOING TO DO NEXT. HE THEN REAPPEARED AT 12:30 O'CLOCK ZOOMING STRAIGHT UP. I GRABBED THE CTLS, DISCONNECTED THE AUTOPLT AND ROLLED A 30 DEG BANK TO THE L. AS I LOST SIGHT OF HIM HE WAS ZOOMING STRAIGHT THROUGH OUR ALT. INTRUDER WAS SQUAWKING 1200, MODE C OFF. NO CLRING TURNS, AND MAY HAVE BEEN SUPERSONIC ON THE DIVES. TCASII HAS NO DEFENSE FOR THIS. NO INJURIES. 1 FLT ATTENDANT LANDED IN A PAX'S LAP. EVERYONE ELSE WAS SEATED, SEAT BELT SIGN WAS OFF. MY EVASIVE MANEUVER WAS RAPID, BUT A COORDINATED TURN. I USED TO BE AN AEROBATIC INSTRUCTOR, TOO. ON THE GND AT BHM (OUR DEST) THE SUPVR AT ZTL TOLD ME THE PLT OF THE JET HAD IMMEDIATELY LANDED AT ALBERVILLE, AL, AND PHONED THE CTR. HE IDENTED HIMSELF AS (PLT NAME) (PHONE NUMBER). HE WAS FLYING FROM THE BACK SEAT WITH A STUDENT IN THE FRONT. HIS ACFT WAS MTR. THERE ARE MANY EXCELLENT PLTS WHO ENJOY AEROBATICS AND FLY RESPONSIBLY AND SAFELY. OTHER ACFT PLT IS NOT ONE OF THEM.

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.