RV-4
Flight Crew Flight Instructor; Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 80; Flight Crew Total 2100; Flight Crew Type 100
Situational Awareness
Conflict Ground Conflict; Less Severe; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Became Reoriented; Flight Crew Returned To Departure Airport; Flight Crew Took Evasive Action
Human Factors
I was engaged in formation training with Aircraft Y over a rural area. We completed our join up training and lead Aircraft Y started a descent over a small reservoir. In the descent; I began to overtake him due to my aircraft's clean aerodynamics and was forced to break away. As I attempted to rejoin Aircraft Y over the reservoir I was in trail and struggling to catch up with him. It was then that I realized we were possibly below 500 ft. AGL and since I was unsure of the [elevation] of the lake; I pulled up quickly to maintain legal distance from boats and people on the water. In all my focus on the lead Aircraft Y; I lost situational awareness and for some reason he accidentally descended below 500 ft. In the future I will be less fixated on the lead aircraft. He possibly did not realize there were people on the open water and by the time he did it was too late to climb away from them; or just didn't realize how low he was due to outside fixation.
Low level section flight over open water or unpopulated area. Operated aircraft closer than 500 ft. to person [and] vessel. As lead I failed to take into account MSL altitude of the reservoir (at 250-300 ft. MSL). On descent looked in at altimeter and had 500 ft. on altimeter and immediately went back outside. Flew past several vessels; estimate within 200-300 ft. Wingman made radio call and we immediately climbed above 1;500 ft. MSL and returned to base.
Flight crew of two small aircraft in formation reported flying below minimum safe altitude.