Narrative:

I was practicing my aerobatic routine (I am a professional air show pilot) in the generally accepted, but not official, practice area. This is a small triangle of airspace near the mountains, ground level about 2000 ft MSL, which is the only area within many mi of my home airport that is more than 4 mi from the center of a federal airway and otherwise uncontrolled and unrestr airspace. Because of its unique status as a practice area, it receives heavy use, both by aerobatic pilots and by students practicing low level ground tracking turns around a pylon, etc. As I was coming out of a tumbling gyroscopic maneuver I noticed a white and blue twin rear engine bizjet type banking steeply away from my location, about 1/2 mi away, and at the same level as I was when I first noticed the airplane. Since I had just recovered from an inverted flat spin (intentionally) it took a second or so to regain straight and level flight away from where I saw the jet, and by the time I turned the airplane back to try to locate it, it had vanished from my visual field. There was never any conflict from my perspective. It appeared to me that my presence might have surprised the jet -- it banked sharply and turned away. I can understand how seeing an airplane going straight up and straight down, tumbling end over end, etc, could be disconcerting to the captain of a bizjet. Also, from my own experience, I know that watching aerobatics from an airplane always makes the aerobatic airplane below the observer airplane look much closer to the ground than it actually is. So I can understand how the pilot of the bizjet may have felt some concern. It would be greatly useful to have a standard frequency for the practice area, since it is not officially marked on the sectional chart, transient pilots have no way of knowing of the intense activity that occurs there. It is my practice to announce my presence and intentions on unicom for cable airport, 123.0. However, with 3 twred and 2 unicom airports within 10 or 15 mi of the practice area, at least some, if not most of the transient traffic through the area is not on that frequency. Also, this area falls right on the most heavily used route into the los angeles basin, since it is just south of the cajon pass. Many aircraft descending to any of the several airports in the area pass right through this area. It would not be my preference to fly there if there were anywhere else legal to fly, but this is the only area where aerobatics can be practiced legally within many mi. I might suggest that delineating the area as a practice area on the chart, and assigning it a specific frequency for both transient and practicing aircraft to announce their intentions and locations, might enhance safety. Callback conversation with reporter revealed the following information: reporter states that there has been no follow up. He feels the bizjet probably reacted to the sight of an aircraft seemingly out of control and exited the area as soon as possible. The aerobatic aircraft was a zlin 50LX, a czech aircraft imported to the united states.

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Original NASA ASRS Text

Title: AEROBATIC PLT FLYING A ZLIN 50LX AND DOING UNUSUAL MANEUVERS IN AN ACROBATIC PRACTICE AREA IS SUDDENLY AWARE OF A BIZJET BANKING STEEPLY AWAY FROM HIS IMMEDIATE VICINITY.

Narrative: I WAS PRACTICING MY AEROBATIC ROUTINE (I AM A PROFESSIONAL AIR SHOW PLT) IN THE GENERALLY ACCEPTED, BUT NOT OFFICIAL, PRACTICE AREA. THIS IS A SMALL TRIANGLE OF AIRSPACE NEAR THE MOUNTAINS, GND LEVEL ABOUT 2000 FT MSL, WHICH IS THE ONLY AREA WITHIN MANY MI OF MY HOME ARPT THAT IS MORE THAN 4 MI FROM THE CTR OF A FEDERAL AIRWAY AND OTHERWISE UNCTLED AND UNRESTR AIRSPACE. BECAUSE OF ITS UNIQUE STATUS AS A PRACTICE AREA, IT RECEIVES HVY USE, BOTH BY AEROBATIC PLTS AND BY STUDENTS PRACTICING LOW LEVEL GND TRACKING TURNS AROUND A PYLON, ETC. AS I WAS COMING OUT OF A TUMBLING GYROSCOPIC MANEUVER I NOTICED A WHITE AND BLUE TWIN REAR ENG BIZJET TYPE BANKING STEEPLY AWAY FROM MY LOCATION, ABOUT 1/2 MI AWAY, AND AT THE SAME LEVEL AS I WAS WHEN I FIRST NOTICED THE AIRPLANE. SINCE I HAD JUST RECOVERED FROM AN INVERTED FLAT SPIN (INTENTIONALLY) IT TOOK A SECOND OR SO TO REGAIN STRAIGHT AND LEVEL FLT AWAY FROM WHERE I SAW THE JET, AND BY THE TIME I TURNED THE AIRPLANE BACK TO TRY TO LOCATE IT, IT HAD VANISHED FROM MY VISUAL FIELD. THERE WAS NEVER ANY CONFLICT FROM MY PERSPECTIVE. IT APPEARED TO ME THAT MY PRESENCE MIGHT HAVE SURPRISED THE JET -- IT BANKED SHARPLY AND TURNED AWAY. I CAN UNDERSTAND HOW SEEING AN AIRPLANE GOING STRAIGHT UP AND STRAIGHT DOWN, TUMBLING END OVER END, ETC, COULD BE DISCONCERTING TO THE CAPT OF A BIZJET. ALSO, FROM MY OWN EXPERIENCE, I KNOW THAT WATCHING AEROBATICS FROM AN AIRPLANE ALWAYS MAKES THE AEROBATIC AIRPLANE BELOW THE OBSERVER AIRPLANE LOOK MUCH CLOSER TO THE GND THAN IT ACTUALLY IS. SO I CAN UNDERSTAND HOW THE PLT OF THE BIZJET MAY HAVE FELT SOME CONCERN. IT WOULD BE GREATLY USEFUL TO HAVE A STANDARD FREQ FOR THE PRACTICE AREA, SINCE IT IS NOT OFFICIALLY MARKED ON THE SECTIONAL CHART, TRANSIENT PLTS HAVE NO WAY OF KNOWING OF THE INTENSE ACTIVITY THAT OCCURS THERE. IT IS MY PRACTICE TO ANNOUNCE MY PRESENCE AND INTENTIONS ON UNICOM FOR CABLE ARPT, 123.0. HOWEVER, WITH 3 TWRED AND 2 UNICOM ARPTS WITHIN 10 OR 15 MI OF THE PRACTICE AREA, AT LEAST SOME, IF NOT MOST OF THE TRANSIENT TFC THROUGH THE AREA IS NOT ON THAT FREQ. ALSO, THIS AREA FALLS RIGHT ON THE MOST HEAVILY USED RTE INTO THE LOS ANGELES BASIN, SINCE IT IS JUST S OF THE CAJON PASS. MANY ACFT DSNDING TO ANY OF THE SEVERAL ARPTS IN THE AREA PASS RIGHT THROUGH THIS AREA. IT WOULD NOT BE MY PREFERENCE TO FLY THERE IF THERE WERE ANYWHERE ELSE LEGAL TO FLY, BUT THIS IS THE ONLY AREA WHERE AEROBATICS CAN BE PRACTICED LEGALLY WITHIN MANY MI. I MIGHT SUGGEST THAT DELINEATING THE AREA AS A PRACTICE AREA ON THE CHART, AND ASSIGNING IT A SPECIFIC FREQ FOR BOTH TRANSIENT AND PRACTICING ACFT TO ANNOUNCE THEIR INTENTIONS AND LOCATIONS, MIGHT ENHANCE SAFETY. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATES THAT THERE HAS BEEN NO FOLLOW UP. HE FEELS THE BIZJET PROBABLY REACTED TO THE SIGHT OF AN ACFT SEEMINGLY OUT OF CTL AND EXITED THE AREA ASAP. THE AEROBATIC ACFT WAS A ZLIN 50LX, A CZECH ACFT IMPORTED TO THE UNITED STATES.

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.