Grand Canyon

The pilot's failure to maintain clearance with terrain during descent for undetermined reasons. Contributing factors were the dark night and mountainous terrain.

Detonation (or pre-ignition) in the n°1 cylinder, which resulted in erosion (burning) of the n°1 piston and subsequent loss of engine power. A factor related to the accident was: the lack of suitable terrain for an emergency landing.

The inflight failure of the airplane's powerplant as a result metal fatigue which allowed the crankshaft to fracture. Contributing to the accident was mountainous terrain of the grand canyon which did not allow a suitable forced landing area.

Improper pilot techniques and crew coordination during the landing attempt, bounce, and attempted go-around.

The National Transportation Safety Board determines that the probable cause of this accident was the failure of the flightcrews of both aircraft to “see and avoid” each other for undetermined reasons. Contributing to the accident was the failure of the Federal Aviation Administration to exercise its oversight responsibility over flight operations in the Grand Canyon airspace and the actions of the National Park Service to influence the selection of routes by Grand Canyon scenic air tour operators. Also contributing to the accident was the modification and configuration of the routes of the rotary-wing operators resulting in their intersecting with the routes of Grand Canyon Airlines near Crystal Rapids.

Occurrence #1: in flight encounter with weather
Phase of operation: cruise - normal
Findings
1. (f) weather condition - clouds
2. (f) terrain condition - mountainous/hilly
3. (f) weather condition - low ceiling
4. (f) weather condition - rain
5. (c) VFR flight into IMC - continued - pilot in command
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Occurrence #2: in flight collision with terrain/water
Phase of operation: climb

Powerplant failure for undetermined reasons. The following contributing factors were reported:
- High density altitude, approximately 5,400 feet
- Rough/uneven terrain,
- Forced landing off airport on land.

The probable cause of the accident was a substantial loss of power from the left engine at a critical point in the takeoff an the failure of the pilot to establish a minimum drag configuration which degraded the marginal single-engine climb performance of the aircraft. The loss of power resulted from the seizure of the turbocharger following a progressive failure of the turbine wheel blades initiated by foreign object ingestion which had occurred previous to this flight and was not detected during maintenance on the engine 4 days before the accident.

The pilot continued VFR flight into adverse weather conditions. The following factors were reported:
- Low ceiling, rain and snow.

The Board determines that the probable cause of this mid-air collision was that the pilots did not see each other in time to avoid the collision. It is not possible to determine why the pilots did not see each other, but the evidence suggests that it resulted from any one or a combination of the following factors: Intervening clouds reducing time for visual separation, visual limitations due to cockpit visibility, and preoccupation with normal cockpit duties, preoccupation with matters unrelated to cockpit duties such as attempting to provide the passengers with a more scenic view of the Grand Canyon area, physiological limits to human vision reducing the time opportunity to see and avoid the other aircraft, or insufficiency of en route air traffic advisory information due to inadequacy of facilities and lack of personnel in air traffic control. The following findings were reported:
- Approaching Daggett, TWA 2 requested its company radio to obtain 21,000 feet as an assigned altitude, or 1,000 on top,
- Company radio requested 21,000 feet IFR from ARTC. This vas denied by ARTC. Request was then made for 1,000 on top. This was approved and clearance issued. The flight climbed to and proceeded at 21,000 feet,
- As an explanation for the denial of 21,000 feet, TWA 2 was furnished pertinent information on UA718,
- The last position report by each flight indicated it was at that time at 21,000, estimating the Painted Desert line of position at 1031,
- The Salt Lake controller possessed both position reports at approximately 1013, at which time both flights were in uncontrolled airspace,
- Traffic control services are not provided in the uncontrolled airspace and according to existing Air Traffic Control policies and procedures the Salt Lake controller was not required to issue traffic information; none was issued voluntarily,
- A general overcast with some breaks existed at 15,000 feet in the Grand Canyon area,
- Several cumulus buildups extending above flight level existed; one was nearly over Grand Canyon Village and others were north and northeast in the area of the collision,
- The collision occurred at approximately 1031 in visual flight rule weather conditions at about 21,000 feet,
- The collision in space was above a position a short distance west of the TWA wreckage area, 17 miles west of or approximately 3-1/2 minutes' flying time from the Painted Desert line of position,
- Under visual flight rule weather conditions it is the pilot's responsibility to maintain separation from other aircraft,
- At impact the aircraft relative to each other converged at an angle of about 25 degrees with the DC-7 to the right of the L-1049. The DC-7 was rolled about 20 degrees right wing down and pitched about 10 degrees nose down relative to the L-1049,
- There was no evidence found to indicate that malfunction or failure of the aircraft or their components was a factor in the accident.