Medium Transport
Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Instructor; Flight Crew Multiengine; Flight Crew Instrument
Flight Crew Last 90 Days 200; Flight Crew Total 14000; Flight Crew Type 6000
Training / Qualification; Communication Breakdown; Confusion
Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued New Clearance; Flight Crew Returned To Clearance
Human Factors
Having accepted the WESLA Four SID departing Runway 28R at SFO; I proceeded as directed in the SID description: Climbing heading 284 to 520 feet; then direct WESLA climbing through 2;000 feet at or below 230 kts; then turn left direct PORTE. About 2 miles prior to WESLA; passing 2;000 feet; I turned left direct PORTE as directed in the guidance. TRACON advised that I should have continued to WESLA before the turn. However; very commonly ATC clears one to proceed direct to another fix reaching a specified altitude. This is usual and customary. No one is 'at or above 2;000 feet' while proceeding direct to WESLA out of 520 feet. So; the turn direct PORTE was entirely in keeping with the guidance as stated.The DEPARTURE ROUTE DESCRIPTION is as follows; 'TAKEOFF RUNWAYS 28L/R: Climb heading 284 to 520 then direct WESLA at or above 2;000 feet at or below 230 kts; then left turn direct PORTE.' That's what I did. Turning just before WESLA reaching 2;000 feet is in keeping with standard phraseology routinely used by FAA. Should the intent be otherwise two words should be added to the route description. Those two words are: 'PASSING WESLA' AT OR ABOVE 2;000 feet.'
Medium Transport aircraft Captain reported failure to meet a crossing restriction resulted in a clearance deviation during departure from SFO.