Douglas DC-3 accident at Mason City, Iowa, 22 Aug 1954

Accident narrative

On August 22, 1954, a Braniff Airways Douglas DC-3 crashed in a farm field approximately 16 miles south of the Mason City, Iowa, airport. The aircraft was demolished by ground impact. Of the 19 people aboard, eleven occupants—including the captain and first officer—were killed outright, and a twelfth died several days later in a hospital. The stewardess and six passengers survived with serious injuries.

**The flight**

Braniff Airways Flight 152 was a daily scheduled flight from Memphis, Tennessee, to Minneapolis, Minnesota, with several intermediate stops. Following a crew change at Kansas City, Missouri, the flight was operated by Captain William Pickering, First Officer William Wilde, and Hostess B. A. Truly. The captain had flown regularly over the route for more than ten years in DC-3 aircraft, and the first officer had previously flown commercially in the Mason City area.

The flight departed Waterloo, Iowa, with a gross weight which was 601 pounds below the maximum allowable weight. Before takeoff, the crew cancelled their instrument clearance and proceeded under visual flight rules (VFR).

**The storm and the crash**

By 1648, a heavy thunderstorm had moved over the Mason City airport and extended southwest. The company radio operator at Mason City was initially unable to contact Flight 152 and relayed weather information through another flight. At 1658, direct radio contact was established, and the flight advised it would hold southeast of Mason City due to thunderstorms to the west and northwest.

Shortly before 1700, a ground witness observed the aircraft about 17 miles south-southeast of the Mason City airport. The witness saw the DC-3, flying at a lower altitude than usual, make a left turn and proceed almost directly west toward a light spot in a thunderstorm. Several eyewitnesses estimated the aircraft's altitude at 400 to 500 feet above the ground as it headed west.

Witnesses reported a vigorous storm in the area. The nearest witness, one mile east of the crash, experienced heavy rain immediately after the aircraft passed overhead. The aircraft disappeared into the lighter spot in the center of the storm and crashed at 1703, eight miles west of where the flight had initiated its left turn.

**What the investigation found**

The aircraft struck the ground on a heading of 2900 degrees True. Ground marks and the extremely disintegrated condition of the bottom of the cabin and center section indicated that the DC-3 impacted in a level lateral and longitudinal attitude, with the landing gear and flaps retracted. The aircraft skipped forward only 48 feet, indicating a low forward speed, but compression bends in the cabin seat support legs and downward distortion of the wing tips substantiated a high sinking velocity.

Investigators found no evidence of structural failure, power failure, or control malfunction prior to impact. The propellers indicated approximate cruise power, and all radio equipment functioned normally.

The Board noted that the flight did not hold southeast of Mason City for any appreciable time. It is possible the captain entered the lighter area between darker clouds to get on the back side of the storm and land at Mason City. The Board noted this light area could be accounted for by the lighter color of a heavy rain curtain, where a very strong downdraft had established.

Ground damage in the vicinity of the crash indicated strong, gusty winds from all directions. A mile east of the crash, 12-inch trees were broken off 18 feet above the ground. Nearby, corn stalks were forced to the ground in 100-foot swirling counterclockwise circles, and 60-foot power line supports—built to withstand steady winds of 85 to 90 mph—were blown down. The Board concluded that a fully developed tornado reaching the ground did not occur, but gusts may have exceeded 80 mph. The Board also noted the possibility of a sudden airspeed loss as the aircraft proceeded into divergent winds from the storm center.

The weather forecasts issued by the U.S. Weather Bureau and the company predicted occasional light rainshowers or thundershowers and local turbulence, but did not indicate the severity of the storm encountered. The Air Force had issued severe weather advisories forecasting heavy thunderstorms, severe turbulence, and gusts to 50 knots for the area, but the Weather Bureau considered its own forecast adequate. Radar storm detection was unavailable from the Weather Bureau at Des Moines because the equipment was inoperative. Air Force radar advisory service was available at Waverly, but the flight did not contact the station.

**Probable cause**

The Board determined that the probable cause of this accident was "that the flight while endeavoring to traverse a thunderstorm area encountered very heavy rain, divergent winds, and strong downdrafts that forced the aircraft to the ground."