Date: 201305
Local time of day: 0001-0600
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Dawn
Aircraft: SR20
Operator: Personal
Operating under: Part 91
Flight plan: IFR
Mission: Personal
Flight phase: Taxi
Aircraft component: Headset
Component problem: Failed
Reporter organization: Personal
Reporter function: Pilot Flying; Single Pilot
Reporter qualification: Flight Crew Commercial; Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Flight Instructor
Human factors: Communication Breakdown; Situational Awareness
Anomaly: ATC Issue All Types; Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural FAR; Ground Incursion Runway; Ground Incursion Taxiway
Detector: Person Air Traffic Control; Person Flight Crew
When detected: In-flight; Taxi
Result: Air Traffic Control Issued Advisory / Alert; General Maintenance Action
Contributing factors: Aircraft; Human Factors; Procedure
Primary problem: Aircraft

Narrative: I taxied and departed from Runway XX without authorization.  I believed the Tower was closed and announced on CTAF.  I did not realize they were open.  Here are the events.  I called Clearance Delivery and Ground for clearance to taxi.  Tower handles Ground and Tower.  I called Ground; but never received a response.  I called several times; I then called Tower several times and got no response.  I turned the aircraft to look at the Tower.  I did not see anyone inside the Tower.  I also looked for light gun signals.  After about 10 to 15 minutes; I began to believe the Tower was still closed since it was so early in the morning.  I assumed; (this was my first mistake; I should not have assumed) that the Tower was not yet open.  I should have verified.  During this time I heard no other aircraft arriving or departing to give me an indication that Tower was open.  I taxied up to Taxiway X and stopped for a couple of minutes announcing my intentions on CTAF and tried calling Tower again; during this time I looked to see if someone was in the Tower again; I did not see anyone in the Tower.  I then taxied to hold short at XX.  I did my run up and then announced my departure intentions on CTAF.  Shortly after departing and at about 700 AGL and turning north; Tower called my N number and asked why I had departed.  This was the first time I had heard from the Tower or anyone.  I responded but got no reply; I responded again.  I did not know it at that time that I was not transmitting.  I then called Tower on my cell phone to speak with them; they told me to call them at my destination.  I do not understand why Tower did not call me much sooner; like when I was taxing; or doing my run up to depart XX.  I have never made an error like this in my flying career; I recognize how grave this error could be.  I made the assumption that Tower was closed and I departed on CTAF; I should not have made that assumption or mistake.  I later determined that it was the headset.  I fixed the issue and was able to communicate over the radio with them.  I did speak with the Tower Supervisor on the phone later and they acknowledged that they heard attempts at transmissions on the tape.  The fault for departing without clearance is mine; I made errors I should not have made.  With respect on how to learn from this and increase safety for all; I believe the Tower should have called me sometime during my taxi; run up; and departure.




Synopsis: SR20 pilot reports calling Ground for an early morning taxi for takeoff and getting no response.  After several more attempts the reporter assumes the Tower is not yet open and uses CTAF procedures to depart.  Once airborne the Tower calls and asks who just departed without clearance.  The headset was found to be defective.