Page:CAB Accident Report, Western Air Lines Flight 636.pdf/2

 San Francisco -
 * 2300 - Measured ceiling 800 feet, broken clouds. Visibility 10 miles, wind west-southwest 7, altimeter setting 29.89.
 * 2315, 10 minutes after takeoff:

Oakland -
 * 2300 - Measured ceiling 700 feet, overcast. Visibility 10 miles, wind west-southwest 4, altimeter setting 29.89.
 * 2312, seven minutes after takeoff:

Flight 636 was cleared direct to the Oakland tower, to remain clear of clouds at a minimum altitude of 500 feet. Takeoff was on Runway 28R at 2305.

Two minutes later, at 2307, the flight called Oakland, advised that it was on a trans-bay clearance to the Oakland tower and requested further clearance to the airport. Oakland tower cleared Flight 636 to enter the traffic pattern for landing on Runway 27R, and gave the wind west at 10 miles per hour. Acknowledgment was the last contact with Flight 636.

Testimony of witnesses firmly established the fact that Flight 636 was normal and routine in all respects between Los Angeles and San Francisco. A walk-around inspection of the aircraft at San Francisco and the absence of any complaints of mechanical or other difficulties by the captain, indicates that N 91303 was airworthy upon departure from that station. It is therefore unnecessary to dwell further on this phase of the flight.

On departure from San Francisco, the gross weight, fuel aboard and the weather conditions were well within the limits prescribed by the Civil Air Regulations and Western Air Lines.

The clearance under which this flight departed San Francisco is known as "Visual Trans-Bay" and is used for traffic between San Francisco and Oakland. It is issued when the ceiling and visibility at both airports is less than 1,000 feet and/or three miles visibility and a minimum combination of ceiling and visibility (sliding scale) is required for its issuance. This procedure was established through the medium of a Joint Operations Letter Revised effective April 10, 1952, for the purpose of expediting traffic between San Francisco and Oakland. The applicable parts of this letter are set forth