Skyhawk 172/Cutlass 172
Flight Crew Instrument; Flight Crew Private
Flight Crew Last 90 Days 30; Flight Crew Total 590; Flight Crew Type 520
Communication Breakdown; Situational Awareness
ATC Issue All Types; Conflict NMAC; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Provided Assistance; Air Traffic Control Separated Traffic; Flight Crew Took Evasive Action
Human Factors
I departed ZZZ on an IFR flight plan to practice approaches. Shortly before my departure; a Mooney formation group departed. There were 2 Mooney formations; a group of 2 (NAME1 flight) and a group of 3 (NAME2 flight). The names are from memory but I believe them to be accurate.The group of 2 departed approximately 15 minutes before my departure; and the group of 3 about 5 minutes before my departure. As I was being vectored for the RNAV XX approach to ZZZ; Approach called out traffic which was not visible to me. The Controller stated that the aircraft/group was supposed to be in contact with Approach; but wasn't for some reason. A few seconds later I saw a Mooney pass below me and slightly to my left. I estimate the vertical gap to be approximately 100 feet. I did not see the other plane that I believe was part of the formation. The flight continued without further incident.I believe this illustrates the hazard of formation flights in busy airspace. Since the Mooney is a low wing plane and I was in front of; and above it; I don't see how the pilot did not see me; unless he was focused on something else; perhaps maintaining his spot in the formation. He was obviously not scanning for traffic or he never would have come that close.
C172 pilot reported a near miss with an aircraft of a formation flight that was not in communication with Approach Control.