Investigation Summary
The investigation by the Civil Aeronautics Board (CAB) highlighted a breakdown in cockpit coordination and several critical handling errors. The flight had been operating on three engines for nearly three hours after the No. 1 engine was feathered near Nashville. Despite this, the crew did not cross-feed fuel to balance the aircraft, leaving the left wing significantly heavier than the right. During the approach to Runway 36, the aircraft was misaligned to the left, prompting the captain to execute a risky S-turn at low altitude. The high bank angle and excessive rudder use caused a skid, which led to fuel sloshing in the No. 4 tank and a momentary loss of fuel pressure to the No. 4 engine. The first officer, fearing a second engine failure, feathered the No. 4 propeller but failed to inform the captain. Simultaneously, the first officer disregarded the captain's order to raise the flaps, fearing an immediate stall. With two engines out on the same side and flaps still extended, the aircraft could not maintain altitude or airspeed, resulting in a stall and impact with a hangar and other buildings.
Final Conclusions
The Civil Aeronautics Board concluded in August 1950 that the probable cause was the faulty execution of an engine-out approach. Contributing factors included the captain's failure to align the aircraft properly on the final turn, the attempt to correct misalignment with a low-altitude S-turn, the failure to balance fuel loads, and the lack of coordination between the captain and first officer regarding the feathering of the No. 4 engine and the operation of the flaps.
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Systems & Failure Modes
Fuel Cross-Feed System
A network of valves allowing fuel to be transferred between tanks to feed different engines; the crew failed to use this to balance the weight after the No. 1 engine was shut down.
Propeller Feathering System
A mechanism to turn propeller blades parallel to the airflow to reduce drag after an engine failure; the No. 4 engine was feathered prematurely due to a transient fuel pressure drop.
Wing Flaps
High-lift devices that increase drag; the first officer's failure to retract them during the attempted go-around prevented the aircraft from accelerating.
Interesting Facts
- 01The aircraft was carrying 1,400 lbs more fuel in the left wing than the right at the time of the crash due to a failure to cross-feed.
- 02The first officer admitted he did not raise the flaps as ordered because he feared the aircraft would stall immediately.
- 03The captain, first officer, and flight engineer survived the crash as the cockpit section broke away from the burning fuselage.
- 04The two flight attendants and 26 passengers were the 28 fatalities recorded in the accident.
- 05The captain was unaware that the No. 4 engine had been feathered until the post-accident investigation hearings.
- 06The crash destroyed the Dallas Aviation School and American Magnaflux buildings and damaged a parked aircraft.
Safety Actions & Advisories
Engine-Out Procedure Review
The investigation emphasized the necessity of maintaining a straight and level attitude when misaligned during an engine-out approach, rather than attempting low-altitude corrective maneuvers.