Accident at Kingston, Utah, 12 Nov 1974 (F-111A)

Accident narrative

About 1804 m.s.t. on November 12, 1974, a United States Air Force F-111A and a Montana Power Company Rockwell Turbo Commander 690A collided in flight near Kingston, Utah. The F-111A was attempting a night air refueling rendezvous with a KC-135 tanker. The pilot of the Turbo Commander, its sole occupant, was killed. The two crewmembers of the F-111A ejected successfully. Both aircraft were destroyed by the collision, post-collision fire, and ground impact.

### The flights

The Turbo Commander, registration N40MP, departed Phoenix, Arizona, at 1650. The pilot had 2,754 flight-hours, including 200 in the Turbo Commander. Although destined for Butte, Montana, the visual flight rules (VFR) flight plan indicated Prescott, Arizona. At 1800, the pilot called the Cedar City, Utah, Flight Service Station, reported his position over the Bryce Canyon VOR, and filed an instrument flight rules (IFR) flight plan to Butte via jet airway J-11 and other routes. He requested flight level (FL) 180 and reported a true airspeed of 270 knots. At 1804, the pilot contacted the Los Angeles Air Route Traffic Control Center (ARTCC), stating he was at 17,500 feet and would like to go to 18,000. Los Angeles ARTCC asked for his position from Bryce Canyon, but N40MP did not reply.

The F-111A, designated Sigma 71, was the lead aircraft in a formation of two F-111As from Nellis Air Force Base, Nevada. The pilot had 2,850 flight-hours, and the weapon systems officer (WSO) had 901 flight-hours. They were scheduled to rendezvous with a USAF KC-135 tanker, designated Toft 51, from Grand Forks Air Force Base, North Dakota.

### The sequence of events

Toft 51 arrived at the Air Refueling Control Point at 1739 and was cleared into an altitude block of FL 180 to 210. The proposed refueling altitude was FL 200. The tanker's wingtip, tail, underbelly, engine nacelle, and refueling boom lights were illuminated, along with red and white flashing anticollision beacons.

The F-111A formation was to join at the Air Refueling Initial Point. Sigma 72 was originally designated the flight leader, but its tactical air navigation (TACAN) and inertial navigation system equipment became unreliable. Unable to navigate accurately, the pilot of Sigma 72 passed the lead to Sigma 71 and flew in formation off its right wing. Because of the equipment problems, the formation passed the initial point 15 to 17 nautical miles to the right of the published track. The change of lead required the Sigma 71 WSO to rapidly accomplish a precontact checklist, reconfigure lighting, and take over navigation. Both F-111As had their anticollision beacons off.

The pilot of Sigma 71 stated that he saw a landing light and beacon at his 12 o'clock position. He called a "tallyho," made a correction to the right to an approximate heading of 330 degrees, and followed the beacon. The WSO got a radar lockon at about 5 miles. As they closed, the WSO called the target at a 4,000-foot range and noted a fast overtake. The pilot checked his instruments, confirming he was at FL 180 with an airspeed of about 320 knots calibrated airspeed. The WSO called a 2,000-foot range, indicating they were closing fast. The pilot checked his airspeed again, looked up, and saw a white light and what he thought was the right outboard engine pod of a KC-135. He pulled back on the control stick and collided with the aircraft.

The crew of Toft 51, who were turning to the refueling heading, heard the tallyho and saw a beacon at their 3 or 4 o'clock position. Shortly after, they saw what they thought were flares, which were actually the fires from the collision.

### What the investigation found

The collision occurred during hours of darkness. Flightcrews reported an overcast layer of cirrus clouds above the refueling track, with no lower clouds and good visibility. The sky was completely black at their altitudes.

The F-111A struck an alfalfa field about 1 mile northwest of Kingston, Utah. The crew escape module landed in a mountainous area about 4 miles southeast. The Turbo Commander broke into pieces scattered along a 9-mile path ending about 2 miles from the F-111A wreckage. Paint marks matching the F-111A were found on several Turbo Commander components. The wreckage area was located just east of the J-11 airway course line.

Radar data indicated the collision occurred at 17,900 feet. The Board concluded that N40MP had been flying along the airway course for at least 4 minutes before the collision. The Board found that the highest authorized VFR cruise altitude for that heading below the Positive Control Area was 16,500 feet, and the pilot of the Turbo Commander should have remained at that altitude until receiving ATC clearance to enter the Positive Control Area. N40MP had only its beacon and position lights illuminated.

The Board found that the Sigma flight was 15 to 17 nautical miles to the right of the air refueling track centerline, outside the track-protected airspace. The Board believed that the hurried atmosphere of changing leads, together with the undetected position error, led the pilot of Sigma 71 to mistake the Turbo Commander's beacon for the tanker's beacon.

The investigation identified several cues the F-111A pilot missed. First, the tanker was turning to the refueling heading and should have been moving from left to right across the windscreen, rather than remaining stationary. Second, the radar provided range information showing a high closure rate, calculated by the Board to be 158 knots. Third, the Turbo Commander's probable heading of 343 degrees was significantly different from the 301-degree heading reported by the tanker. Finally, because the tanker was at FL 200 and the F-111A was at 17,900 feet, the beacon should have moved up on the windscreen as the distance decreased. The Board noted that any object appearing stationary on the windscreen is on a collision course. The Board believed the pilot disregarded these cues because he firmly believed the beacon was the tanker. As the overtaking aircraft, the F-111A was required by right-of-way rules to alter course and pass well clear.

### Probable cause

The National Transportation Safety Board determined that the probable cause of this accident was "the F-111A pilot's misidentification of the Turbo Commander as a refueling tanker with which he intended to rendezvous. Contributing to the misidentification was his failure to use prescribed procedures and techniques during rendezvous with a tanker aircraft for refueling."