Lockheed 10-A accident at Sioux City, Iowa, 11 Jun 1941 (NC-16058)

Accident narrative

On June 11, 1941, at about 12:04 a.m. CST, a Mid-Continent Airlines Lockheed 10-A (NC 16058) overran the runway while landing at the Municipal Airport in Sioux City, Iowa. The aircraft sustained major damage when it crashed through a boundary fence and into a plowed field. None of the three crew members or seven revenue passengers aboard were injured.

**The flight** The trip, designated as Flight 8 of June 10, originated in Tulsa, Oklahoma, with a final destination of Minneapolis, Minnesota. Following a crew and aircraft change at Kansas City, Missouri, the flight proceeded to Omaha, Nebraska. The crew consisted of Captain William Moomaw, First Officer Peter Carruthers, and Steward A. C. Warr. Delayed by weather, the flight departed Omaha at 11:28 p.m. for Sioux City.

Contact flying conditions prevailed between Omaha and Sioux City, but severe static made radio communication difficult. The crew listened only intermittently and missed two special weather broadcasts from Sioux City: one at 11:45 p.m. reporting wind, and another at 11:56 p.m. reporting heavy rain. At 11:53 p.m., the flight reported its position over Onawa at 3,000 feet with unlimited visibility.

**The approach and landing** At 11:57 p.m., the Mid-Continent radio operator at Sioux City cleared Flight 8 to land. He provided a weather report of a 1,300-foot ceiling, three miles visibility in light rain, and a south surface wind at 2 mph.

First Officer Carruthers was at the controls. Relying on the 2 mph wind report, he initiated an approach from south to north on the 3,173-foot North-South runway. Captain Moomaw stated that he thought the approach was rather high, but did not consider it serious enough to take over at that time.

The aircraft touched down approximately midway down the runway during heavy rainfall that restricted visibility. The airport's boundary and range lights were abnormally dim and invisible to the crew, giving a false indication of the remaining runway length. When the East-West runway near the north boundary became visible in the landing lights, the crew realized they were too close to the end of the runway for an emergency takeoff.

Captain Moomaw took control and applied full brakes. Finding no noticeable braking effect, he attempted to groundloop to the right by using the right brake and left motor. The Lockheed turned 15 to 20 degrees but continued along a straight path. Seeing the fence posts and boundary light standards ahead in the landing light beam, Moomaw straightened the aircraft to hit the obstruction head-on. The plane went through the fence, crossed a road, and came to rest in a normal position about 200 feet into a plowed field.

**What the investigation found** The investigation found no malfunctioning of the aircraft or its components, including the brakes.

The Board determined that the weather report provided to the crew was inaccurate. Mid-Continent Airlines encouraged station personnel to make and relay their own weather observations. The company radio operator had stepped outside and seen the hangar windsock, about 125 yards away, hanging down—apparently because it was water-soaked and heavy. The operator stated he saw the Weather Bureau anemometer turning slowly but did not enter the office to read the indicator. Consequently, the crew expected light rain and negligible wind, but actually landed in heavy rainfall with a tailwind of approximately 8 mph.

Additionally, the investigation disclosed that the boundary lights at Sioux City had known defective wiring, which caused them to dim intermittently during rain. Their failure during Flight 8 deprived the crew of the principal landmark needed to judge their position on the runway.

**Probable cause** The Civil Aeronautics Board determined the probable cause was an "inaccurate weather observation made by the Company radio operator and reported to the flight crew, resulting in pilot making a downwind landing."

The Board cited the failure of the airport lighting system as a contributing factor.