Date: 201502
Local time of day: 1201-1800
Location: SCT.TRACON, CA
Flight conditions: VMC
Weather elements / visibility: 20
Light: Daylight
Aircraft: Small Aircraft; Low Wing; 1 Eng; Retractable Gear
Operator: Personal
Operating under: Part 91
Flight plan: VFR
Mission: Personal
Flight phase: Cruise
Airspace: Class B SCT
ATC / advisory: TRACON SCT
Reporter organization: Personal
Reporter function: Single Pilot; First Officer; Pilot Flying; Gate Agent / CSR
Reporter qualification: Flight Crew Flight Instructor; Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Flight Engineer; Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness; Distraction; Confusion; Communication Breakdown
Anomaly: ATC Issue All Types; Airspace Violation All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Flight Crew Returned To Clearance
Contributing factors: Procedure
Primary problem: Procedure

Narrative: Departing MYF; requested and received from MYF ground control a Miramar (NKX) transition northbound for Class B. We acknowledged and were told NKX Tower was closed and 'when able' to contact SOCAL on 125.3 for flight following. We informed the MYF Tower we would stay at 2;900ft MSL to avoid the overlying Class B at NKX. When established Northbound over NKX we attempted to contact SOCAL on 125.3. I was pilot flying from the right seat and was concentrating on traffic; course and altitude. The controller (125.3) did not respond to our initial call as he was communicating with multiple aircraft. The clearance from MYF Tower implied that contact with SOCAL was optional as NKX Tower airspace was closed. Thinking we were under the overlying Class B at 2;900ft MSL we continued to monitor 125.3 when SOCAL made a blind call to an 'aircraft northbound over NKX to squawk ident'. That being our relative position we acknowledged the call. The controller informed us that we had in fact not received a Class B clearance and to make a turn back toward MYF. We complied immediately and turned southbound at 2;900ft. MSL. The SOCAL controller informed us that there was no conflict and the miscue was not a problem. He explained to us that when NKX Tower was closed that SOCAL (125.3) becomes responsible for controlling the NKX underlying airspace. The controller reiterated to us that it was no problem and to consider it a learning experience. He then asked us to contact MYF Tower. We called MYF to request overflight of their Class D at 2;900ft MSL which they approved and we gave us clearance to proceed to the shoreline. I feel that do to the nonstandard departure procedure do to the closure of the NKX tower that MYF Tower could have been more precise in the fact that SOCAL was now 'controlling' the airspace normally controlled by NKX. KUDOs to SOCAL for the explanation and treating this as a learning event. I immediately shared this event with other pilots at my company to prevent this in the future. It has been brought to my attention by a controller from another San Diego ATC facility who has experience in this 125.3 SOCAL sector that this is not an uncommon event 	and not surprised of the miscue and confusion.




Synopsis: Pilot reports of violating airspace. Controller told pilot to contact approach control and that a tower was closed. Pilot thought it was optional to contact Approach. Approach called out in the blind for pilot to ident. Pilot was told by approach that he should have called and the they should have asked for a Class Bravo clearance. ATC explained issue to pilot and a learning experience and did not violate the pilot.