Douglas DC-4 accident at Aberdeen, Maryland, 19 Dec 1946

Accident narrative

On December 19, 1946, at 1807, an Eastern Air Lines Douglas DC-4 and a Universal Air Lines Douglas DC-3 collided in flight approximately three miles north of Aberdeen, Maryland. Both aircraft sustained major damage but remained controllable and made safe emergency landings. None of the 22 passengers and three crew members aboard the DC-3, nor the 56 passengers and four crew members aboard the DC-4, received other than minor injuries.

### The Flights

Universal Air Lines Flight 7, a DC-3, was a scheduled flight from Newark, New Jersey, to Miami, Florida, with a refueling stop in Raleigh, North Carolina. The pilot filed an instrument flight plan to cruise at 2,000 feet via Airway Amber 7. The flight departed Newark at 1707. The crew was not advised of any traffic en route. The captain had accumulated 2,600 flight hours, and the co-pilot had 3,100 hours.

Eastern Air Lines Flight 605, a DC-4, was a non-stop flight from Newark to Miami. The pilot filed an instrument flight plan for 2,000 feet. Because Flight 605 would operate along the same route as Flight 7 between Newark and Washington, D.C., Airway Traffic Control cleared the DC-4 for 2,000 feet but required the flight to be conducted under contact flight rules. Prior to departure, the crew was advised that Flight 7 was proceeding southbound along the same route at 2,000 feet. Flight 605 departed at 1722, fifteen minutes after the DC-3. The captain had 16,356 flight hours, and the co-pilot had 5,028 hours.

### The Collision

The flights were operating near the center of a high-pressure area of polar continental air. Weather conditions were at all times above contact flight rule minimums, and the Board concluded that weather was not involved. Civil twilight had ended at 1719, and with no moon in the sky, the flights were conducted in complete darkness.

One hour after departing Newark, in the vicinity of Aberdeen, the DC-3 collided with an object the pilots initially mistook for a large bird. At no time did either pilot observe another aircraft. The top right side of the pilot's compartment was badly crushed, but the aircraft was still controllable. The captain decided to proceed to Baltimore for an emergency landing. While en route, the crew sighted the lights of Phillips Army Air Field in Aberdeen and landed safely there.

Aboard the Eastern DC-4, the captain never observed another aircraft. The co-pilot suddenly saw the lights of an aircraft close to and to the left of the DC-4, immediately rolled into a right bank, and forcefully pulled the nose up. Both pilots felt the impact almost simultaneously. Encountering no difficulty in controlling the aircraft, the crew continued to Washington National Airport at a reduced airspeed and landed safely.

### What the Investigation Found

Investigators found no evidence of mechanical failure or equipment malfunction in either aircraft prior to the collision. Both crews testified that their navigation lights were operating normally, and investigators confirmed the lights were functioning properly after the respective landings.

Parts torn from both aircraft were located in an orchard between four and five miles north-northeast of Aberdeen. The Board concluded the collision occurred close to the east edge of Airway Amber 7.

Inspection of the DC-3 revealed extensive damage to the forward top fuselage above the right side of the cockpit, with the radio compartment's top skin torn off. The DC-4's fuselage below and in front of the horizontal stabilizer was extensively damaged, with a portion of the bottom fuselage and tail skid carried away. The primary control cables were undamaged, though the structure above them was demolished to a depth of 17 inches above the original fairing.

Marks on the DC-4's left stabilizer included embedded segments of a porcelain insulator, which matched the radio lead-in insulator on the top right of the DC-3. A deep vertical indentation on the DC-4's stabilizer leading edge exactly matched the broad side of the DC-3's vertical wooden aerial mast.

Analysis of the impact marks and airspeeds indicated the flight paths intersected at a 74-degree angle. Immediately prior to impact, the DC-3 was at a relative bearing of 43 degrees to the left of the DC-4, while the DC-4 was approximately 63 degrees to the right of the DC-3's pilot compartment.

The Board noted that a structural member in the DC-4 cockpit restricts vision at a 45-degree angle to the left, which may have partially hidden the DC-3. However, the Board concluded that safe operation requires pilots to assume responsibility for looking around structural members.

Because both aircraft were operating under contact conditions, the Board applied the rule of "see and be seen," noting neither pilot could presume exclusive use of the airway. The Eastern DC-4 crew had been informed of the DC-3 ahead of them, and the captain testified he anticipated overtaking Flight 7 near Baltimore. The Board concluded the Eastern crew was insufficiently alert. Similarly, although the Universal DC-3 was on an instrument clearance, it was operating in contact conditions and its altitude was not protected. The Board concluded the DC-3 pilots were also not sufficiently alert to other traffic.

### Probable Cause

The Board concluded that the greater laxity must be charged to the Eastern DC-4 flight crew, but that the lack of vigilance of each flight crew was contributory.

The Board determined that "the probable cause of this accident was the lack of vigilance on the part of the pilots of both aircraft."