Douglas DC-7 accident at Memphis, Tennessee, 13 Jan 1963

Accident narrative

On January 13, 1963, at 0233 central standard time, Delta Air Lines Flight 8715, a Douglas DC-7, collided with an unoccupied U.S. Air Force C-123B parked on the military ramp at Memphis Municipal Airport. The DC-7 was operating as a ferry flight to Jackson, Mississippi. Of the five crew members aboard, the captain was killed and three others were injured. Both aircraft sustained substantial damage.

### The flight

Before departure, a Delta mechanic discovered a hydraulic leak at the Meletron pressure switch. With permission from Delta's Atlanta maintenance base, the switch was disconnected and capped, and hydraulic fluid was added. The mechanic explained the modification to the captain, noting it did not affect the normal operation of the basic hydraulic system. At the mechanic's request, the captain operated the auxiliary hydraulic pump, and both men were satisfied it worked.

The flight engineer completed his walk-around inspection and pre-start checklist, using the auxiliary pump to build hydraulic pressure to 3000 p.s.i. He stated he did not move the hydraulic bypass lever, leaving it in the down position in accordance with the checklist.

The five crew members—the captain, first officer, flight engineer, and two stewardesses—were the only occupants. Both stewardesses went forward to the cockpit to observe the takeoff. After the engines were started, the first officer stated the hydraulic pressure was normal at 3000 p.s.i.

At approximately 0229, Memphis Ground Control cleared the flight to Runway 27. Following a question from the crew about the route, the controller instructed them to taxi east past the north-south runway, turn left at the second taxiway, and taxi parallel to the east-west runway. The flight acknowledged.

### The collision sequence

The aircraft proceeded east on Runway 9 but turned left onto Taxiway "D". Seeing this, the ground controller transmitted new instructions to turn right on the ramp ahead and hold short of Runway 27. The flight did not acknowledge. Shortly after, the controller transmitted, "Eighty-seven fifteen... use caution in taxiing on the military ramp." The controller stated he issued this warning because he could see the parked C-123B illuminated in the DC-7's landing light beam. The flight did not acknowledge this message either.

In the cockpit, neither the flight engineer nor the first officer monitored the hydraulic pressure gauge during taxiing. The flight engineer stated the first indication of difficulty was an exclamation from the captain, which he interpreted to mean the captain "couldn't steer the airplane." The captain then pulled the throttles into the reverse range.

The first officer stated he saw the parked aircraft, called out "air brakes" at least twice, and saw the captain bring the throttles out of reverse and reach for the air brake bottle just as they collided. One of the stewardesses stated she had seen the parked plane ahead of them earlier but was not worried because she assumed they would be turning.

At 0233, the DC-7 struck the left wing of the C-123B. The C-123B's left wing rear spar penetrated the upper nose section of the DC-7, collapsing the instrument panel, shearing the control yoke, and impaling the captain. The first officer fell from the emergency escape rope and was injured, while one stewardess jumped from the crew door and the other remained at the aft passenger door with the flight engineer.

### What the investigation found

The Civil Aeronautics Board found no evidence of powerplant, structural, or hydraulic system failure prior to impact. The emergency air brake system and landing lights were capable of normal operation. The Board believed the disconnected Meletron switch did not contribute to the accident, as it was an additional component that did not interfere with the basic hydraulic system.

Post-accident examination showed the hydraulic pressure regulator operated within tolerance and the bypass lever was in the correct down position. The emergency air brake pressure indicator read zero only because the handle had been pulled out by the C-123B wing spar, opening the pressure line.

The Board noted that the captain misinterpreted the instruction to "turn left at the second taxiway," which placed the aircraft on Taxiway "D" heading toward the military ramp.

Investigators found it significant that the crew did not use the normal hydraulic brakes, the auxiliary hydraulic pump, or the emergency air brake system to stop. Neither surviving flight crew member felt any deceleration associated with braking, nor did they see the captain attempt to use the brakes. If the normal brakes had not been working prior to turning onto the military ramp, the Board noted, the captain most probably would have said so. At that point, either he or the first officer should have turned on the auxiliary hydraulic pump to build pressure for the brakes.

The first officer assumed there was no hydraulic pressure because the captain allegedly could not steer, but he did not check the pressure gauge or attempt to turn on the auxiliary hydraulic pump located next to his hand. The Board noted that propeller reversing is relatively ineffective at speeds below 50 to 60 knots, whereas the emergency air brakes would have provided immediate braking action and locked the wheels.

The Board also found it difficult to understand why the crew did not hear the controller's two radio transmissions, suggesting they were preoccupied in the cockpit. Because the stewardess saw the parked aircraft early enough that she was not worried, the Board concluded the C-123B was visible and sufficiently far away to have been avoided.

### Probable cause

The Board determined the probable cause of this accident was "the crew's inattention to duty while taxiing on an unfamiliar taxiway at night and the captain's failure to stop the aircraft in sufficient time to avoid striking a parked aircraft."