While poor weather in the Bay Area can cause significant delays at SFO, there are many other causes of delays. SFO’s April 2000 Delay Study¹ analyzed Department of Transportation data² and found that on days when the weather was good all day an average of 149 domestic flights arrived late (1997-1999). Over 43% of the delays identified occurred on days when the weather was good all day. When weather was a factor, delays increased, but the majority of delays were still caused by the 149 flights on average that arrive late regardless of the local weather:

When one factors in the number of days each type of weather occurred, one can estimate the share of delays caused by local weather. An examination of all delays covered by the analysis in the delay Study indicates that only 18.8% of the delays during the 3-year period were caused by weather at SFO.

When weather is a factor, SFO and the airlines claim almost all delays are due to bad weather even though many are due to other causes including:

Aggressive scheduling by airlines

Slow airline loading, unloading, and fueling

Failure by airlines to hold sufficient aircraft and crews in reserve

Labor disputes between airlines and employees

Computer and data line failures

Out of area weather

Antiquated FAA equipment/system

New runways at SFO will have no effect on the 81.2% of delays that are caused by factors other than local weather. While SFO recently claimed that it is forced to close an arrival runway 30% of the time, its own studies reveal that the correct figure is below 16% and possibly below 10% ⁴. Over the next 2 years, new radar and approach systems will further reduce the percentage of time SFO must close an arrival runway due to weather.

Departure delays due to local weather are limited at SFO because two departure runways may be used even in low visibility conditions. Any departure delay at SFO related to weather is usually caused by the weather at the destination airport. The FAA will order a plane to wait at SFO if there is a concern that the destination airport will be overloaded.

SFO’s proposed runways will do nothing to increase the airport’s arrival capacity in clear weather. Delays that occur during good weather conditions will continue and even worsen if SFO continues to increase the number of flights scheduled. The airlines are constantly pushing for new flights and their first concern is ticket sales, not smooth operations. American Airlines CEO Don Carty admitted to USA Today, "the accusation that airlines overschedule is absolutely right. Of course we overschedule.⁵"

A recent Department of Transportation (DOT) report ⁶ found that 74% of gate departure delays were due to airlines operations issues such as passenger loading and unloading, aircraft refueling, and baggage handling. Airline operational issues are especially likely to lead to delays because of aggressive scheduling by the airlines. The DOT report stated, "we found that air carriers schedule departures at some airports above their capacity under ideal conditions (e.g. clear weather and all runways available)."

A United Airlines press release dated April 20, 2000 indicates that one of its delay reduction techniques will be dual end boarding- allowing passengers to load and unload through two doors to reduce turnaround times. Clearly there is a limited amount of time allowed for turnarounds if dual end boarding is a technique that will make the difference between a flight leaving on time or not.

United Airlines has indicated that it will eliminate 30% of the existing delays through operational changes. The FAA is already planning to move ahead with upgrades to air traffic control equipment and systems and most of these upgrades should be in place many years before new runways could be completed. The estimates in SFO’s Runway Reconfiguration Study indicate that the completion date for new runways would not be until 2010 or later ⁷.

¹ Reducing Weather-Related Delays & Cancellations at SFO, Charles Rivers Assoc./John F. Brown Co.
² ASQP data covers domestic flights by 10 largest U.S. airlines excluding commuter flights
³ Figures derived from Delay Study, Appendix C.2, Table 3 by averaging 1997, 1998, and 1999 figures
⁴ Analysis of SFIA Runway Reconfiguration Impact on Regional Air Transportation Systems, Working Paper No. 9, Page 2-14 - P&D Aviation (3/15/99)
⁵ USA Today, September 13, 2000
⁶ Report No. CR-2000-112 (July 25,2000)
⁷ URS Greiner Runway Reconfiguration Study (April 1999) - Table 5.5.3.1

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