SAN FRANCISCO — Hundreds of flights at San Francisco International Airport were delayed Friday as air traffic control staffing constraints and operational changes during the opening day of Fleet Week affected airport traffic. By Friday evening, 457 arrivals and departures had been delayed and eight flights canceled, according to flight-tracking data. The Federal Aviation Administration imposed a ground delay program, forecasting average delays of 57 minutes. Some flights faced waits of up to 10 hours. The FAA said staffing constraints prompted the restrictions and cited changes to airport operations after the afternoon air show. Its advisory did not say how many air traffic controllers were assigned to Fleet Week operations. The agency projected SFO would handle 36 to 45 arriving aircraft per hour during the affected period, and scheduled the restrictions to remain in place through 11:59 p.m. Friday. Ground delay programs regulate incoming air traffic when an airport cannot safely handle its usual volume. Aircraft can be held at their departure airports instead of taking off and waiting in the air. The delays coincided with the first day of Fleet Week air shows over the San Francisco waterfront. Fog disrupted Friday’s performances: the Navy’s Blue Angels began their demonstration shortly before 4 p.m. but cut it short because of poor visibility over the bay. Air shows were scheduled to continue Saturday and Sunday, with the Blue Angels expected to perform both afternoons. Travelers were advised to check with their airlines for updated flight times.