This article first appeared in the April 1971 Flight Test News.
A certification team comprised of engineers and pilots from the Carrier Suitability Branch of Flight Test Division and the Automatic Carrier Landing System Branch of the Naval Electronic Systems Test and Evaluation Facility, recently conducted SPN-42 Mode I (automatic control to touchdown) certification trials in USS ENTERPRISE (CV AN-65) using NATC instrumented and Carrier Air Wing Fourteen F-4J aircraft. Project engineers, instrumentation and maintenance support personnel loaded aboard ENTERPRISE at anchorage at Hampton Roads, Virginia, on 17 January 1971. Project pilots flew the test airplanes aboard and tests commenced 18 January at 1400.
The primary purpose of the certification trials was to verify safe and satisfactory performance of the newly installed SPN-42 automatic carrier landing system under operational conditions prior to clearance for fleet usage. A statistical sample of forty landings using each SPN-42 channel was required to evaluate vertical and lateral glidepath control, longitudinal and lateral touchdown dispersion, hook-to-ramp clearance, sink speed and air- plane attitude at touchdown. Most of these data were obtained from photo-instrumentation of the landing area and SPN-42 instrumentation.
During the January trials strong gusty winds were encountered in the VaCapes area, and due to the extreme turbulence, only 42 of 117 attempted automatic landings were completed. Glideslope control and touchdown dispersion were not acceptable and trials were rescheduled for 4-6 February. The test team personnel again journeyed to Norfolk and boarded ENTERPRISE the afternoon of 3 February. She sailed 4 February in fog and rain with more of the same predicted for the VaCapes area. Pax had poor visibility and freezing rain and aircraft could not launch. Chances for flight operations in the VaCapes area were grim and time was running out as ENTERPRISE had a schedule to meet on the west coast. That evening the decision was made to move east into an area with better weather. The ship requested and received permission to operate near Bermuda and Pax River was advised.
Four F-4J aircraft arrived overhead at 1600L, 5 February and made ACLS approaches until sundown. Flight operations were continued all day the sixth and until 1030 the seventh. A total of 232 approaches were flown, 172 of which were completed to touchdown. Based on qualitative observations by the engineers, pilots and LSO it was concluded that the SPN- 42 performance was acceptable for automatic landing control under limited conditions and an interim Mode I certification was recommended. More precise information will be obtained from analysis of the large volume of data collected.
Pax River personnel were flown off to NAS Bermuda on the seventh and ENTERPRISE began her transit around “The Horn”.
Carrier Suitability Branch project work in ENTERPRISE went smoothly although faced with adverse weather and a tight schedule. The successful completion of the sea trials was accomplished through the cooperation and efforts of all concerned and resulted in increased capabilities for the Fleet.
This article first appeared in the April 1971 Flight Test News.
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