United States Air Force - USAF (since 1947)

The exact cause of the accident could not be determined with certainty. Considered as 'most probable' was an over-pressurization under the cargo floor, an area that houses fuel and other potential sources of ignition. An explosion caused by the ignition of accumulated combustible vapors occurring in that area could, in fact, rapidly propagate to adjacent areas where fuel is present. There was also 'strong evidence' of explosive over-pressures in the forward, aft and upper fuel tank areas. Significantly, investigation showed that were the walls or fittings of the rubber bladder cells containing the volatile liquid to fail, fuel or vapor could be released into the tank cavity and in turn migrate to other part of the aircraft.

The USAF KC-135 was on an IFR flight plan and executing a TACAN 03L approach to Luke AFB. The AA-1 had departed Sky Harbour Airport and had been released by phoenix TRSA. The AA-1 was heading westerly in airspace designated as a special traffic area and was required to have been at or below 2,000 ft msl. A pilot of another aircraft who was trailing the AA-1 stated that a low broken cloud cover was encountered and he had to descend to about 2,000 ft to remain 500 ft below the bases. He stated the pilot of the AA-1 did not descend but appeared to be skimming along in and out of the bases of the clouds. He noticed the KC-135 descending through the cloud deck followed immediately by the collision. The collision occurred about 5 mi south of Luke AFB at an altitude of 2,500 ft msl. The logbook of the AA-1 pilot indicated this was his first trip to the phoenix area. Luke AFB was depicted on the north side of the sectional chart only. VOR airway #16 was split along an e-w line with the northern and southern halves being depicted on each side of the chart.

Occurrence #1: midair collision
Phase of operation: cruise - normal
Findings
1. En route charts - inadequate
2. (c) vfr procedures - improper - pilot in command AA-1
3. (f) lack of familiarity with geographic area - pilot in command AA-1

Uncontrolled collision with ground during a go-around after the pilot failed to maintain flying speed. The following contributing factors were reported:
- Local instructional and pilot qualification checkout with simulated se training,
- Pilot-in-command presumed at controls.

At 1049:48 EDT, FAA lost radar contact with the aircraft. The aircraft was cruising at flight level 290 at .78 Mach and was performing a navigational training leg. Navigational legs are normally flown on autopilot, and FAA altitude readouts showed the aircraft was within 100 feet of assigned altitude, characteristic of autopilot flight. The aircraft commander, Capt Joseph Emilio, occupied the right pilot seat and a passenger, Mrs. Peggy Emilio, occupied the left pilot seat. Also in the crew compartment were the 2 navigators, Lt Col Benjamin B. Frederick and Capt Donald V. Fonke, and 2 passengers, Mrs. Linda Fonke and SSgt Joseph T. Brundige. This phase of flight, the navigational leg, was the least demanding on the pilot and was the logical time for the passengers to come forward to view the cockpit area. There is no evidence that the presence of the passengers in the crew compartment contributed to, or caused, the accident. For undetermined reasons, the aircraft pitch trim moved to the full nose-down position. The autopilot can overcome the trim until near full nose-down. The aircraft then rapidly pitched over, most likely upon release of the autopilot, and induced sufficient negative "G" forces to cause the generators to trip off line and loss of all AC electrical power. The pitch trim could not then be moved electrically. This condition, while unusual, can be easily controlled if prompt corrective action is taken; however if corrective action is delayed approximately 8 seconds, the aircraft pitch angle will be greater than 30° nose-down in the airspeed in excess of 350 KIAS. Under these conditions, the aircraft cannot be controlled until the pitch trim is moved toward neutral. While it is clear that recovery was delayed, the reason for the delay is unknown. The aircraft became uncontrollable and entered a steep descent. The aircraft emerged from the clouds at 2,000 feet above ground level (AGL) and was intact. Airspeed was in excess of 400 KTAS and die to angle was 20 to 30 degrees. Engine power was above 2.0 engine pressure ratio (EPR). At approximately 1,500 feet mean sea level (MSL) an explosion occurred inside the pressurized compartment of the fuselage and weakened the aircraft structure to the extent that catastrophic failure of the aircraft followed immediately. Cause of this explosion is undetermined; however, the aircraft was in an unrecoverable condition at the time of the explosion and a crash was already inevitable.

The exact cause of the accident could not be determined with certainty.

Weather conditions were good at the time of the accident and no mechanical anomalies were found on the aircraft, its equipments and engines. Without any further details, it was reported that the runway light system installed by British Calvert System was considered as a contributing factor.