Date: 202102
Local time of day: 1201-1800
Location: PDK.Airport, GA
Flight conditions: VMC
Light: Daylight
Aircraft: Small Aircraft
Operator: Personal
Operating under: Part 91
Flight plan: VFR
Mission: Personal
Flight phase: Final Approach
Airspace: Class D PDK
ATC / advisory: Tower PDK
Second aircraft: Small Aircraft
Reporter function: Single Pilot
Reporter qualification: Flight Crew Instrument; Flight Crew Private
Human factors: Communication Breakdown; Confusion
Anomaly: ATC Issue All Types; Conflict NMAC; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Landing Without Clearance; Ground Incursion Runway
Result: Flight Crew Requested ATC Assistance / Clarification; Flight Crew Took Evasive Action
Contributing factors: Procedure; Airspace Structure
Primary problem: Procedure

Narrative: I departed ZZZ after topping off my aircraft fuel tanks. I flew VFR in VMC conditions to PDK. The traffic pattern very congested so much so that several aircraft had difficulty obtaining clearance to enter the controlled airspace at PDK. After monitoring the tower frequency; I elected to call ATL Approach to request a VFR ILS to PDK for a full stop landing. This would help me to practice a VFR approach; setting up the approach; capturing the localizer and glide-slope; Because I was solo I remained alert to visually remain clear of all aircraft nearby.I contacted ATL Approach and received a discreet transponder code as well as VFR vectors for the approach; I was vectored through the ILS localizer for sequencing and then cleared for the approach just outside of the FAF CHAMB and was transferred to the PDK tower frequency.The radio traffic was so heavy that I was not able to transmit before the tower called my call sign and cleared me for landing number 2 behind jet traffic. Because I was cleared to land #2 behind the jet; this contributed to my understanding I would land on Runway 21L; the longer runway used by Jets. The parallel Runway 21R is shorter and primarily used by piston and training aircraft.I continued on approach on the Localizer and Glide slope until short final. When I was approximately over the Runway 21 L approach end I observed Aircraft Y fly over head at approximately 75 ft. at a faster speed. I immediately called the tower and reported the aircraft overhead while side stepping to the right to go around. The tower sequenced me to land on the parallel Runway 21R and I continue to a safe landingThe issue was I was cleared for the ILS by ATL approach and expected to land on Runway 21L. Also I was cleared initially by the tower to land #2 behind Jet traffic However; the tower said that they cleared me to land on [Runway] 21R.I have been flying from this airport for over XX years and I as well as many other pilots regularly receive runway landing changes often on short final. In this case I may have misunderstood or did not hear correctly the landing clearance and as a result had a near miss with another aircraft.Contributing factors was the radio frequency congestion as well as the high volume of aircraft in the airspace; and my expectation to land on the longer runway behind jet traffic. Also the Aircraft Y pilot did not see me as he approached from above and behind my aircraft; which also contributed to the near miss. I have on board Aircraft X an L3 active TCAS as well as ADSB traffic advisory. I do not believe I heard or saw a traffic alert on my avionics.




Synopsis: Pilot reported ATC confusion and clearance resulted in a NMAC on short final to PDK airport.