Near midair collision.

Attributes
ACN	275573
Time
Date	199406
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : o56
State Reference	CA
Altitude	msl bound lower : 3400 msl bound upper : 3600
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	general aviation : personal
Make Model Name	Christen (& Pitts) Undifferentiated or Other Model
Operating Under FAR Part	Part 91
Flight Phase	cruise other
Flight Plan	None
Aircraft 2
Operator	general aviation : personal
Make Model Name	Christen (& Pitts) Undifferentiated or Other Model
Operating Under FAR Part	Part 91
Flight Phase	cruise other
Flight Plan	None
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : commercial pilot : instrument
Experience	flight time last 90 days : 11 flight time total : 983 flight time type : 337
ASRS Report	275573
Person 2
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	conflict : nmac non adherence : far
Independent Detector	other flight crewa
Resolutory Action	flight crew : took evasive action
Consequence	Other
Miss Distance	horizontal : 0 vertical : 50
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Aircraft 1 and aircraft 2 were on a formation aerobatic practice flight at approximately 3600 ft MSL. Aircraft 2 was on the right wing of aircraft 1, separated by approximately 50 ft. The formation was headed southeast and initiated a shallow descent to gain required airspeed for entry into a looping maneuver. The lead aircraft (aircraft 1) was in inverted flight. Aircraft 2 was in upright flight. The aircraft (1 and 2) were in radio communication with the lead aircraft (aircraft 1) calling pitch changes to the wing aircraft. After gaining the required airspeed in the descent to 3400 ft MSL, aircraft 1 resumed level (inverted) flight. At that time aircraft 3 was sighted slightly below and in front of aircraft 1 on a reciprocal heading. Aircraft 1 initiated a shallow (inverted) climb to increase the vertical separation from aircraft 3. Aircraft 3 passed below the formation by approximately 50-100 ft. It is unknown if aircraft 3 ever saw the other aircraft. The dark (gray/green) color of aircraft 3 was difficult to pick out against the backgnd, san francisco bay. The pitch angle of aircraft 1 along with the wing and fuselage confign put aircraft 3 in a blind spot during the inverted descent. Formation confign made abrupt, rolling evasive action impossible.

Original NASA ASRS Text

Title: NMAC.

Narrative: ACFT 1 AND ACFT 2 WERE ON A FORMATION AEROBATIC PRACTICE FLT AT APPROX 3600 FT MSL. ACFT 2 WAS ON THE R WING OF ACFT 1, SEPARATED BY APPROX 50 FT. THE FORMATION WAS HEADED SE AND INITIATED A SHALLOW DSCNT TO GAIN REQUIRED AIRSPD FOR ENTRY INTO A LOOPING MANEUVER. THE LEAD ACFT (ACFT 1) WAS IN INVERTED FLT. ACFT 2 WAS IN UPRIGHT FLT. THE ACFT (1 AND 2) WERE IN RADIO COM WITH THE LEAD ACFT (ACFT 1) CALLING PITCH CHANGES TO THE WING ACFT. AFTER GAINING THE REQUIRED AIRSPD IN THE DSCNT TO 3400 FT MSL, ACFT 1 RESUMED LEVEL (INVERTED) FLT. AT THAT TIME ACFT 3 WAS SIGHTED SLIGHTLY BELOW AND IN FRONT OF ACFT 1 ON A RECIPROCAL HDG. ACFT 1 INITIATED A SHALLOW (INVERTED) CLB TO INCREASE THE VERT SEPARATION FROM ACFT 3. ACFT 3 PASSED BELOW THE FORMATION BY APPROX 50-100 FT. IT IS UNKNOWN IF ACFT 3 EVER SAW THE OTHER ACFT. THE DARK (GRAY/GREEN) COLOR OF ACFT 3 WAS DIFFICULT TO PICK OUT AGAINST THE BACKGND, SAN FRANCISCO BAY. THE PITCH ANGLE OF ACFT 1 ALONG WITH THE WING AND FUSELAGE CONFIGN PUT ACFT 3 IN A BLIND SPOT DURING THE INVERTED DSCNT. FORMATION CONFIGN MADE ABRUPT, ROLLING EVASIVE ACTION IMPOSSIBLE.

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.