Date: 201405
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Weather elements / visibility: 10
Light: Daylight
Aircraft: Amateur/Home Built/Experimental
Operator: Personal
Operating under: Part 91
Flight plan: None
Mission: Personal
Flight phase: Cruise
Airspace: Class D ZZZ
ATC / advisory: Tower ZZZ
Second aircraft: Amateur/Home Built/Experimental
Reporter organization: Personal
Reporter function: Pilot Flying; Single Pilot
Reporter qualification: Flight Crew Multiengine; Flight Crew Flight Instructor; Flight Crew Commercial; Flight Crew Instrument
Human factors: Situational Awareness; Distraction; Other / Unknown
Second reporter function: Single Pilot
Anomaly: Inflight Event / Encounter Other / Unknown
When detected: In-flight
Result: Aircraft Aircraft Damaged; Flight Crew Became Reoriented; Flight Crew Landed As Precaution
Contributing factors: Human Factors; Procedure
Primary problem: Ambiguous

Narrative: During an Airshow; while flying the slot position in a 4-ship diamond formation; I overtook the leader (#1) and my propeller struck his tail spring. Half of each propeller blade was cut off/lost. Engine/propeller still producing adequate power/thrust. Both aircraft landed without further incident. Flight was conducted in conjunction with a Jet Truck as part of the Airshow. This truck has 3 jet engines and also large fire plumes coming out the top of the truck. The large heat signature affected the 4-ship flight flying over the top of the truck at approximately 50 feet. Also; the noise and speed of the oncoming Jet Truck affected my willingness to descend into the path of the oncoming truck to deconflict with my flight lead.  I needed to descend to miss my flight lead and did not feel I could do so due to the truck. Corrective actions: Higher altitude over the truck. No airshow smoke from #1 at low altitudes.


Second narrative: While in an airshow the slot aircraft propeller contacted the tailwheel boom of the lead aircraft during a low altitude jet truck race. The Team had completed a normal rejoin and was steady for the inbound run. Formation was in level upright flight. The flight was established in level flight at a set power setting. Slot described how he saw the truck directly in front and when he passed over it heard the jet 'booms'. He observed then that he had moved under the lead aircraft and rapidly pulled power to idle. The two wingmen commented how they saw the slot aircraft rapidly move forward. Lead stated that he felt his aircraft tail rise (evident in the post incident review of the photos); apparently from the bow wave effect of the slot aircraft. Contact was made at this point and the formation rose up and discontinued the act. Lead checked with the slot aircraft to ascertain if he had any control difficulties and if he could return to the airport. Slot advised he was making good power and engine was smooth during climbout. He was cleared off and a call to airboss was made to facilitate his immediate landing. Lead requested a visual inspection of his aircraft by a remaining wingman. He noted one tailwheel spring was missing. Lead advised air boss of missing spring. It was not clear until after parking all aircraft that a prop strike had occurred. While the slot pilot didn't remember entering lead's smoke; photographs taken during the event show the canopy partially obscured during the overtake.


Synopsis: Two pilots involved in a midair collision during a low altitude formation flight describe the circumstances that caused the event.