Lockheed 1049H accident at San Francisco , California, 3 Feb 1963 (N-97402)

Accident narrative

On February 3, 1963, a Slick Airways Lockheed 1049H, registration N 97402, crashed and burned during an instrument approach to runway 28R at San Francisco International Airport. The cargo flight, which had an inoperative glide slope receiver, struck approach lights short of the runway, climbed briefly, and crashed. Of the three crew members and five passengers aboard, the captain, first officer, and two passengers were killed. The remaining four occupants were seriously injured, and the aircraft was destroyed by fire.

### The flight

Slick Airways Flight 40Z was operating as a cargo flight from Norfolk, Virginia, to China Lake, California. The crew consisted of Captain Richard A. MacCallum, First Officer William H. Coryell, and Flight Engineer John J. Walik. The captain had approximately 18,000 flight hours, and the first officer had 18,600 hours.

After departing an en route stop in Dallas, Texas, the flight engineer noted the alternating current (AC) voltmeter pegged at the maximum reading of 150 volts. The first officer then informed the engineer that he had lost all radio navigation instruments. A check revealed all AC radio fuses had blown. In-flight attempts to restore power were futile, and the crew diverted to Albuquerque, New Mexico, landing at 0105.

A company repairman determined that power supply units for both VOR receivers, transformers for both ADF receivers, and the ILS glide slope receiver tubes and filter condensers were burned out. The VOR and ADF units were replaced with parts from a replacement aircraft. Following repairs, the aircraft had functioning VHF transmitters and receivers, one VOR receiver, and one ADF receiver. The glide slope receiver remained inoperative.

Because of space limitations on the replacement aircraft, 3,750 pounds of cargo consisting of two missile motors were reloaded onto Flight 40Z. Five non-revenue passengers also boarded. The crew did not brief the passengers on emergency procedures and exits, nor was a briefing required. The flight departed Albuquerque at 0823 on a visual flight rules (VFR) flight plan for San Francisco.

### The approach

The flight to the San Francisco area was conducted in visual weather conditions. En route, the crew received weather updates indicating indefinite ceilings of 200 to 300 feet and visibility as low as 1/16 of a mile in fog and smoke at San Francisco. Over the Mt. Hamilton intersection, the crew canceled their VFR flight plan, requested an instrument clearance, and held in the San Jose area waiting for the weather to improve.

At 1152, the crew requested an approach to San Francisco. Approach Control advised that visibility had improved to 3/4 of a mile and cleared the flight for an ILS approach. The crew requested radar advisories on the localizer approach. At 1204, contacting the tower, the crew again requested "radar advisories glide slope on the localizer frequency." The local controller cleared the flight to land and acknowledged the request with "radar advisories on localizer voice." At no time did the crew inform air traffic control of their inoperative glide slope receiver.

During the approach, the Precision Approach Radar (PAR) controller provided the flight's position relative to the glide slope and localizer course. At 1204:50, the tower advised the flight of a fog bank on the approach end of the runway. The final radar advisory was given at 1206:36, placing the aircraft 150 feet left of course, passing the middle marker, and 25 feet above the glidepath.

The PAR controller did not attempt to contact the flight after it passed the middle marker. He stated he continued to monitor the aircraft's position and did not observe the target leave the glide slope until it climbed to about 200 feet in a slight left turn near the runway threshold.

At approximately 1207, controllers in the tower heard a loud sound. About 10 seconds later, the aircraft slid out of the fog bank on fire, coming to rest at the intersection of runways 28L and 1R.

### What the investigation found

The investigation determined that the aircraft first struck the approach light structure 1,170 feet from the runway threshold, approximately 11 seconds after passing the middle marker. The aircraft struck multiple light stations, climbed to about 200 feet, and then crashed 1,900 feet beyond the threshold, with the left wing tip and No. 1 propeller making first ground contact.

The Board found no evidence of failure in the propellers or engines. The flight engineer testified that the engines and propellers operated normally and that the throttles were retarded just before initial impact. He also recalled the first officer stating that lights were in sight to the right, and believed the captain made a slight correction to the right as a result.

When the aircraft struck the approach lights, the nose gear assembly was forced rearward into the fuselage, penetrating the flight deck floor. This severed or pinched flight control, trim tab, and engine control cables, as well as hydraulic lines. The Board concluded that following the initial impact, the airplane was no longer fully controllable.

Weather minimums for the approach were a 200-foot ceiling and 1/2 mile visibility. Slick Airways operations specifications permitted landing if local visibility was reduced by surface weather such as ground fog, provided the runway was plainly visible and the pilot had adequate visual reference. The Board noted that the crew continued the descent following passage of the middle marker and was following the approach lights into restricted visibility. The Board concluded the crew did not have adequate visual reference due to the fog and permitted the aircraft to descend into the approach lights.

The Board examined the air traffic control services provided. Procedures required the PAR controller to advise the flight of its distance from touchdown each mile on final; however, only two distance advisories were given. Furthermore, if a pilot does not report the runway in sight, the controller is required to advise that radar advisories are terminated when the aircraft reaches the middle marker, and then continue monitoring for hazardous deviations. The controller did not advise the flight that advisories were terminated. Because the aircraft struck the lights 109.3 feet below the glide slope, the Board concluded the controller failed to monitor the flight during the 11 seconds after the middle marker, as a dangerous descent would have been noticeable on radar.

The Board noted that the approach light system was operating, but it could not be determined if the sequence flashing lights were functioning. When the aircraft destroyed the lights, a warning buzzer in the tower should have sounded, but controllers did not hear it. The Board believed the buzzer had been turned too low, meaning a prior failure of the lights would have gone undetected.

Regarding the evacuation, the flight engineer and three passengers escaped. The engineer opened a smoke removal window, which jammed the right crew entrance door so it could only be raised 12 to 14 inches. The Board believed that although not required, an emergency briefing might have saved additional lives and reduced injuries, as only two survivors were familiar with the emergency exits.

### Probable cause

The Board determines the probable cause of this accident was the continuation of an instrument approach after adequate visual reference was lost below authorized minimums. Inadequate monitoring of the instrument approach by the PAR controller was a contributing factor.