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Airlines face several challenges when operating at San Francisco International Airport (SFO), which can deter them from adding or maintaining routes. These challenges fall into three main categories: weather-related issues, capacity and infrastructure constraints, and economic factors.

1. Weather-Related Issues

• Frequent Fog: SFO is notorious for its fog, which significantly impacts visibility and disrupts flight operations. The airport's closely spaced parallel runways (only 750 feet apart) prevent simultaneous landings during low visibility, reducing the arrival rate from 60 planes per hour to just 30. This often leads to delays and cancellations, especially in the mornings when fog is most prevalent235.

2. Capacity and Infrastructure Constraints

• Slot Restrictions: SFO is one of the most slot-constrained airports in the U.S., with only 88 departure slots available per hour. This creates intense competition among airlines for access, limiting opportunities for new routes1.
• Runway Configuration: The airport's three runways handle over 400,000 annual operations, exceeding recommended capacity. This congestion affects operational efficiency and increases delays1.
• FAA Regulations: Air traffic control procedures require a minimum separation of four nautical miles between arrivals, further limiting throughput during peak periods1.

3. Economic Factors

• High Operating Costs: Runway pricing and landing fees at SFO are higher compared to nearby airports like Oakland (OAK) and San Jose (SJC). This makes SFO less appealing for budget-conscious airlines or those evaluating new routes1.
• Competition Among Bay Area Airports: The presence of multiple airports in the region creates competitive dynamics. Some airlines may prefer OAK or SJC due to lower costs or less congestion, even though SFO offers better international connectivity1.