Background
Eastern Air Lines Flight 642 was a scheduled passenger flight from Miami, Florida to Boston, Massachusetts, with an intermediate stop in Jacksonville, Florida. The flight was operated with a Lockheed Constellation aircraft, registration N112A. The captain received a weather briefing from the company forecaster, and the flight was dispatched under an Instrument Flight Rules (IFR) flight plan via Victor Airway 3 at a cruising altitude of 11,000 feet.
Flight and Crew
The crew consisted of Captain Thomas Francis McBrien, Pilot John Jay Rinyu, Flight Engineer Charles Calvin Devine, and Flight Attendants Emma Elizabeth Williams and Clara Dorothea Rioseco. There were 12 passengers on board. The flight was scheduled to depart Miami International Airport at 2340 on December 20, but due to a late inbound aircraft, departure occurred at 0212 on December 21. The aircraft's gross weight at departure was 85,944 pounds, well under the maximum allowable takeoff weight of 107,000 pounds, and the load was properly distributed.
Sequence of Events
Routine en route radio reports were made. At 0315, the flight reported over Daytona Beach at 11,000 feet, estimating arrival over Jacksonville at 0336. The company's Jacksonville station provided the flight with the 0248 weather report: thin obscuration, 2 miles visibility, ground fog, wind north-northwest at 6 mph, with 30 percent of the sky obscured. The flight then received an air traffic control clearance to cross the Jacksonville middle marker at 2,500 feet and maintain that altitude until further advised. The flight was to contact approach control when over Sunbeam Intersection.
At 0331, Flight 642 reported over Sunbeam Intersection (16 miles south-southeast of Imeson Airport) and was cleared for an ILS approach to runway 5. The Jacksonville weather was given as partial obscurement, visibility one-half mile, altimeter 30.18. Shortly thereafter, the weather was updated to indefinite 300-foot obscurement with one-half mile visibility in fog. The flight's ILS minimums for the approach were a 200-foot ceiling and one-half mile visibility. After acknowledging the weather, the flight reported leaving Sunbeam at 2,500 feet.
Later, the flight queried approach control about other traffic and was advised there was none. The flight was requested to report when over the outer marker inbound. Flight 642 reported over the outer marker and was cleared to land. Shortly after, the tower controller observed a large flash in the vicinity of the ILS middle marker. Calls to the flight went unanswered, and an emergency was declared.
Accident and Investigation
It was subsequently learned that N112A had crashed approximately six-tenths of a mile southwest of the threshold of runway 5. The main wreckage was located 212 feet northwest of the ILS middle marker and 3,486 feet southwest of the runway threshold. The accident occurred at 0343 local time.
The first point of impact was with the top of a small pine tree approximately 200 feet below the ILS glide path, 260 feet to the left of the extended centerline, 4,000 feet from the runway threshold, and 420 feet southwest of the middle marker. The aircraft then struck a 50-foot oak tree, shearing off its upper 20 feet. The aircraft continued, striking other large trees, which disintegrated both wings and a portion of the empennage. Ground impact occurred on a heading of approximately 55 degrees magnetic. The distance from the first tree struck to the farthest piece of wreckage was 801 feet. Explosion and fire occurred immediately upon impact.
Investigation found no evidence of failure of the airframe, power plants, controls, or other components. Weather at the airport was marginal with local fog and restricted visibility, but at the last report, conditions were above the carrier's minimums. Ground navigational facilities, including the ILS, functioned normally. There was no reported operating difficulty by the crew, and no other known aircraft were in the immediate area. The aircraft descended considerably below the glide path and below the minimum altitude before reaching the middle marker.
Probable Cause
The Civil Aeronautics Board determined that the probable cause of the accident was that during the final portion of an ILS approach, the pilot, for reasons not determinable, either permitted or caused the aircraft to deviate to the left of course and descend below the glide path to an altitude too low to clear ground obstructions.