Date: 201908
Local time of day: 0601-1200
Location: TVY.Airport, UT
Flight conditions: VMC
Weather elements / visibility: 10
Light: Daylight
Aircraft: Skyhawk 172/Cutlass 172
Operator: Personal
Operating under: Part 91
Flight plan: None
Mission: Training
Flight phase: Descent
Airspace: Class E TVY
ATC / advisory: CTAF TVY
Second aircraft: Small Aircraft
Reporter organization: Personal
Reporter function: Pilot Flying; Single Pilot
Reporter qualification: Flight Crew Private
Human factors: Communication Breakdown; Situational Awareness
Anomaly: Conflict NMAC
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Took Evasive Action
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: I was performing air work (steep turns; practice emergency descents; stalls; etc.) along a north-south route east of TVY. During each pass (south to north and north to south) I made radio calls and shallow banked 180 degree turns in order to watch for traffic. I also had an EFB with ADSB-In traffic information. At the south end of the valley; with a southerly heading; at 7500 feet; I performed a practice emergency descent; turning to the left at 45 degrees of bank.  Just before starting this maneuver; I heard a radio call from another aircraft stating that they were at the 'North end of the valley and would proceed south at 5800 feet in order to join traffic for Runway 17'. I noted this call but did not believe it would be a conflict since I thought they were in a different area of the valley. I had also just prior made a call stating that; 'Skyhawk XXXXX is performing maneuvers at 7500 ft. and below; 5nm east of the airport.' I descended from 7500 ft. to about ~6100 ft. during my emergency descent and rolled out on a northerly heading to practice preparation for an emergency landing. At this time I did not see any oncoming conflicting traffic; however my attention was divided between the outside; a checklist; and maintaining airspeed since I had the engine at idle and wanted to practice setting up an appropriate best glide speed. After working through the emergency checklist I noticed the aircraft passing underneath me with a relatively small clearance between the two aircraft; maybe 50 ft. horizontally and 80 ft.-100 ft. vertically. The rate of closure was such that by the time I had reacted by adding power the aircraft had already passed. I believe myself and the other pilot did not take sufficient steps to confirm each other's position. I did not confirm which part of the valley the aircraft was going to fly down and the aircrafts pilot did not confirm my location or intentions. The aircraft never appeared on my EFB's traffic display (although other aircraft in the area did). Additionally; a contributing factor to me not seeing the other aircraft was that I was distracted by maintaining airspeed and bank angle while performing an emergency descent. In addition to scanning for traffic prior to maneuvers I also looked at my EFB. Had the aircraft had ADSB out I believe this near miss could have been avoided since I would note that aircraft positioned at the north end of the valley and specifically scanned for it. Another possible prevention technique is that if I had been clearer about my intention 'Skyhawk XXXX performing emergency descent 7500 ft. to 6000 ft. ...' then the aircraft might have decided to delay flying underneath me. Alternatively; if the aircraft had stated 'Traveling down the east bench at 5800 feet I might have delayed my practice maneuver.




Synopsis: C172 Pilot reported a NMAC while training.