Date: 201503
Local time of day: 1201-1800
Location: SFO.Airport, CA
Flight conditions: VMC
Weather elements / visibility: 30
Light: Daylight
Aircraft: Small Aircraft; High Wing; 1 Eng; Fixed Gear
Operator: FBO
Operating under: Part 91
Flight plan: None
Mission: Training
Flight phase: Cruise
Airspace: Class B SFO
ATC / advisory: TRACON NCT; Tower SFO
Aircraft component: Communication Systems
Component problem: Design; Malfunctioning
Reporter organization: FBO
Reporter function: Instructor
Reporter qualification: Flight Crew Commercial; Flight Crew Flight Instructor; Flight Crew Instrument; Flight Crew Multiengine
Human factors: Communication Breakdown; Distraction; Situational Awareness; Time Pressure; Troubleshooting; Workload
Anomaly: ATC Issue All Types; Aircraft Equipment Problem Less Severe; Inflight Event / Encounter Other / Unknown
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Exited Penetrated Airspace; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Took Evasive Action
Contributing factors: Environment - Non Weather Related; ATC Equipment / Nav Facility / Buildings
Primary problem: ATC Equipment / Nav Facility / Buildings

Narrative: Contacted NORCAL and was cleared into Class B at/below 2000 ft.; proposed route of flight was from the Golden Gate Bridge via HWY 101 over SFO then south for landing.Experienced radio interference over downtown San Francisco at 1500 ft. Sounded like a local radio station breaking through onto both aircraft COMM's with high volume static hash. Was instructed by NORCAL to change frequencies to SFO tower.Contacted SFO tower; they replied with our full callsign but was unable to understand all of their call. We could hear them continuing to call us; but were unable to copy all of transmission. As we were turning around to head North (away from SFO) and away from Class B we entered 1NM into Class B at 1500 ft.Then contacted NORCAL and explained that due to radio issues we would not continue into Class B and opted for an alternative route to destination.I experienced this radio interference a few weeks prior in another airplane in the same location. It prevented us from flying our desired flight route and from maintaining desired communications with ATC. Other pilots have subsequently remarked that they have experienced the same radio interference in this location; particularly at low altitude; but have said that often NORCAL's signal is strong enough to break through the hash.

Callback: The reporter flies through this area frequently and has experienced the 'noise' starting near downtown Oakland up to the Berkeley Marina but no 'noise' out over the Bay to the Golden Gate Bridge. Approaching downtown San Francisco over the Marina; the noise becomes clearer and loud enough for the reporter to believe the source is a talk show frequency. Other pilots with whom the reporter has discussed the issue believe the sound over the City to be a music station. 80% of this reporter's recent flights in different aircraft have experienced the 'noise' in that area. The reporter believes the 'noise' is strongest below 2;500 feet over the City and not detectable at 3;500 feet. On this day neither NCT nor SFO could clearly break through the 'noise' although NCT is strong enough; most times; to overcome the extraneous signals.



Synopsis: A pilot over San Francisco reported a commercial radio broadcast loud enough to block NCT and SFO Tower necessitating the flight's exit from Class B airspace.