Date: 201507
Local time of day: 0601-1200
Location: T75.TRACON, MO
Flight conditions: IMC
Weather elements / visibility: Rain; 2
Light: Daylight
Aircraft: Small Aircraft; Low Wing; 1 Eng; Retractable Gear
Operator: Personal
Operating under: Part 91
Flight plan: IFR
Mission: Personal
Flight phase: Climb
Airspace: Class B STL
ATC / advisory: TRACON T75
Second aircraft: Small Aircraft; Low Wing; 1 Eng; Retractable Gear
Reporter organization: Personal
Reporter function: Pilot Flying; Single Pilot
Reporter qualification: Flight Crew Commercial; Flight Crew Multiengine; Flight Crew Instrument
Human factors: Communication Breakdown; Confusion; Distraction; Situational Awareness
Anomaly: ATC Issue All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Air Traffic Control Separated Traffic; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Returned To Clearance
Contributing factors: Human Factors; Procedure
Primary problem: Procedure

Narrative: We departed in a two plane formation IFR to UNU direct. While enroute but still with STL departure; the TRACON supervisor; came up and asked a series of questions about why we were in formation and filed IFR. He stated IFR formation flight was reserved for military aircraft but not civil aircraft. I do not believe the supervisor was correct on that point. We explained that we had briefed the flight and that the dash 2 airplane was manned by a former military pilot with lots of formation experience. The supervisor stated that he would have to direct us to separate. We didn't argue but followed instructions to separate and continue. As the dash 2 pilot I found the transition from visual formation reference to instruments not difficult but somewhat time consuming changing heading and dialing in a different transponder code. The necessity of separation seems to me to have been entirely unnecessary and doubled our burden on ATC. Both pilots are familiar with FAR requirements for formation flight and we insured we had met all regulation requirements. The supervisor offered to take my cell number for a subsequent call to explain; I gave him my cell phone number which he read back. We continued the flight to UNU uneventfully. The supervisor never called me. Of course; we received numerous traffic calls from other approach controllers and Chicago Center since we were within 5 miles of each other. It was the forced transition to instrument reference that bothers me. I did not have difficulty. Had we been in very low visibility or heavy turbulence the split transition to instruments could have been disorienting for the second pilot. At the time we were in smooth air and about 2 miles visibility. My aircraft [Aircraft X] is well equipped and certified for IFR flight.




Synopsis: Pilot is filed and flying in a formation flight with another IFR aircraft. ATC Front Line Manager (FLM) asks pilot why they are filed as a flight of two and states that is reserved for military flights. Pilot doesn't argue with ATC FLM and flight breaks up. Pilot wonders why they had to break up as a flight and ATC told them they would call later and explain. ATC never called pilot to explain.