Page:CAB Accident Report, Slick Airways Flight 25C.pdf/8

-8- Other than by pilot reports, there was no way to determine the visibility within the fog bank extending out over the approach light system for runway 28R. No pilot reports were given during the 15-minute period preceding the accident.

The service to be provided by a PAR controller in a radar monitored ILS approach is set forth in the FAA Air Traffic Procedures Manual. It states that

"Instrument approaches... shall be monitored and radar advisories shall be furnished whenever the reported weather is below badic VFR minima. Such advisories shall be issued in accordance with the following.

"B. Pilots shall be notified immediately whenever radar observation reveals a situation which, in judgment of the controller, is likely to affect the safety of the flight;

"C. Flight making an approach shall be advised...   2. Of the distance from touchdown each mile on final..."

"E. Regardless of the type of approach being monitored, advisories shall be terminated and the pilot so advised when:   1. The pilot reports the approach lights or runway in sight, or    2. The Controler observes the aircraft to have reached the position when the azimuth safety zone lines terminate, whichever is earlier. If the pilot does not make such report upon reaching the position where the azimuth safety zone lines terminate, the flight shall be monitored to the approach end of the runway and advisories issued in accordance with B above."

On the PAR scopes in use at the San Francisco International Airport facility at the time of the accident, the safety zone lines terminated at the ILS middle marker.

The controller testified that a deviation of at least 25 feet from the glade slope would be noticeable on the 3-mile radar scope and further that "... if aircraft made a steep descent at the middle marker I would consider that a hazardous condition." He stated further that he had monitored the aircraft throughout the approach and did not observe the target deviate below the glide slope after passing the middle marker.

The provisions of Special Civil Air Regulation No. 445 stipulate that the ? in command of aircrasft being operated in controlled airspace under instrument flight rules must report immediately any in-flight malfunctions of navigation or communications equipment to Air Traffic Control.

Analysis

The ILS glide slope receiver was known to be inoperative at the time of departure from Albuquerque. It could not be determined if this was a result of the previous in-flight malfunctinos or because of mishandling during the troubleshooting process at Albuquerque.