Date: 201604
Local time of day: 1201-1800
Location: D01.TRACON, CO
Flight conditions: VMC
Weather elements / visibility: Thunderstorm; Windshear; 10
Light: Daylight
Aircraft: Small Aircraft; Low Wing; 1 Eng; Fixed Gear
Operator: Personal
Operating under: Part 91
Flight plan: VFR
Mission: Personal
Flight phase: Initial Approach
Airspace: Class D APA
ATC / advisory: Tower APA
Reporter organization: Personal
Reporter function: Captain; Single Pilot
Reporter qualification: Flight Crew Instrument
Human factors: Distraction; Confusion; Communication Breakdown; Situational Awareness; Workload; Troubleshooting; Time Pressure
Anomaly: ATC Issue All Types; Aircraft Equipment Problem Less Severe; Airspace Violation All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: In-flight
Contributing factors: Human Factors; Procedure
Primary problem: Procedure

Narrative: 90 miles from APA I contacted Denver Center and received flight following for my destination at APA with a discrete squawk code and I was radar identified. At sixty miles out while radio traffic was light I requested routing clarification (through Class B or outside) and was told the next controller would advise. I was handed to Denver approach who was busy and told to remain clear of Class B. I listened to the APA AWOS (Uniform) and then loaded both tower (primary) and ground (standby) into com two and navigated to APA below and clear of Class B. As I got approximately 12 miles from APA (I did not actually note this distance; it just seemed close) Approach told me to contact Tower.At this point I hit the com two button on the audio panel and could hear the tower directing traffic. It was busy but there were enough quiet moments for me to call the tower with a standard flight following handoff (they have me radar identified; they know I'm landing APA so I need only confirm altitude and uniform). I get no response. I could have been stepped on (two radios transmit at the same time); so I call again during the next quiet moment. No response. Blocked or stepped on is not likely three times; I can still here the tower so I call a third time. No response. I worry my radio is not transmitting (if my volume was set too low I would have heard the tower attempting to call me).I reload com one and then receive the reply: 'Aircraft X turn east'. At this point I am three miles from the airport and I turn outbound prior to being brought back and landing. I confirmed that com two was transmitting. The tower may have ignored my call as he was too busy; my radio may have malfunctioned so I wasn't transmitting. I feel that Denver approach may have waited too long to hand be over to tower; resulting in my entering Class [D] airspace prior to establishing radio communication. If in fact ATC was ignoring my call this is clearly a threat to safety as I (should have) held at the edge of Class [D] airspace but I'm directly in the path of two other airports and on a frequency with a controller who won't talk to me? I believe the correct tower phraseology is 'aircraft calling remain clear of Class [D]'. This I understand and can respond to.




Synopsis: Pilot reported an airspace violation while experiencing radio difficulties. Pilot questioned if he should have continued inbound or if ATC was ignoring him do to traffic load.