Date: 201604
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Weather elements / visibility: Clear; 10
Light: Daylight
Aircraft: Small Aircraft; High Wing; 1 Eng; Fixed Gear
Operator: Personal
Operating under: Part 91
Flight plan: None
Mission: Personal
Flight phase: Climb
Airspace: Class E ZZZ
ATC / advisory: TRACON ZZZ
Second aircraft: Small Aircraft; High Wing; 1 Eng; Fixed Gear
Reporter organization: Personal
Reporter function: Pilot Flying; Single Pilot
Reporter qualification: Flight Crew Private
Human factors: Situational Awareness; Communication Breakdown
Anomaly: Conflict NMAC; Inflight Event / Encounter Other / Unknown
Detector: Person Flight Crew
When detected: In-flight
Result: Aircraft Aircraft Damaged; Flight Crew Took Evasive Action
Contributing factors: Airspace Structure; Human Factors
Primary problem: Human Factors

Narrative: Two Cessna 172 aircraft were involved in this incident. Aircraft X was departing ZZZ; and aircraft Y was approaching ZZZ1 [a nearby airport].  Pilot aircraft X departed non-towered airport and continued listening on CTAF until abreast of numbers at northern end of runway; then switched to [approach control frequency] with intention to make contact for VFR Advisory. Noted heavy traffic volume on frequency.At approximately 3 miles NE of ZZZ and altitude approximately 3;000 feet MSL; and while still waiting for clear channel on [approach frequency]; aircraft x experienced impact from above on the left wing. Pilot immediately noticed aircraft Y beside and slightly ahead on the left-hand side; heading in approximately the same direction.  Strength of impact felt more comparable to having had a tennis ball thrown at the plane; rather than anything more substantial such as metal-to-metal contact. Pilot of aircraft X immediately reduced engine speed to three-quarter throttle and commenced level flight to assess situation.  Concluded that aircraft X was in normal flying condition with no damage apparent; and that aircraft Y had come from 4 o'clock behind and above; and that some part of aircraft Y had impinged on upper surface of left wing of aircraft X. Aircraft Y flew to a lower level and meandered off in the direction of ZZZ1.  Pattern of flying of aircraft Y suggested it was observing aircraft X to assess effect of impact. Aircraft X maintained listening on [Approach frequency] and heard no transmissions from or to aircraft Y. No communication occurred between the two aircraft. Having concluded that aircraft X was in normal flying condition with no apparent damage; pilot continued with flight to home-base airport after establishing contact with Approach and request for VFR Advisory. Aircraft X made safe landing at [home-base airport].  Visual inspection of aircraft X showed a small dent; approximately 1/4 inch deep; on the topside of the left wing; more or less just above the attachment point for the wing strut.  Light scrape marks coming from the 4 o'clock direction were also visible. From the light scrape marks on the upper wing surface of aircraft X; aircraft Y approached from exactly the 4 o'clock direction. Assuming an airspeed 100 - 115 knots; the relative velocity at impact was 20 - 30 knots. Prior to impact; aircraft Y was not visible since it came from behind and above.  As viewed from the cockpit of aircraft Y; aircraft X would have approached from the ten o'clock direction at 15 to 25 degrees below the horizon.




Synopsis: The pilot of a small aircraft reported contact with another small aircraft from behind and above. Both aircraft were able to continue for normal landing.