Page:CAB Accident Report, Pan American Flight 320.pdf/1



A model S-428 Sikorsky, NC 15574, owned and operated by Pan American Airways, Inc., of New York, received minor damage in an accident which occurred about 5:35 p.m. on September 25, 1941, on Biscayne Bay, Miami, Florida. There were no personal injuries. The occupants were 17 revenue passengers and a crew of 7, including Captain Francis Scott Key Lewis and First Officer William Griffin Reese, Jr., one flight mechanic, two radio operators, and two flight stewards. Both the captain and the first officer were properly certificated and appropriately rated.

Pan American Airways Flight No. 520 of September 23, 1941, originated at Barranquilla, Colombia, and was en route to Miami, Florida, with scheduled intermediate stops at Kingston, Jamaica, and Cienguegos, Cuba. As the flight approached them it received a radio message from the company's ground station that the wind was "north 5", and that there were two rain squalls in the Vicinity, but the landing area was clear and smooth. The flight at that time was contact, and a landing approach was started toward the north from an altitude of about 800 feet. The carburetors were adjusted to standard position for landing, the engines were set at 2250 r.p.m. and 15 inches of manifold pressure. The flaps were extended to the 35—degree position. Shortly after contact with the water had been made, and as the aircraft was descending, the flaps were raised and the stabilizer was placed in a nose-heavy position. As the aircraft settled off the step, the right wing dropped, the right wing pontoon struck the water and the aircraft started to turn to the right. The pilot reapplied power to the right outboard engine and succeeded in regaining control of the ship after it had made a turn estimated at from 45 to 100 degrees. The company's landing launch was dispatched to the scene and the aircraft was led in and docked.

Investigation disclosed that the aircraft was loaded below the authorized gross. There was no evidence that the aircraft was landed in an unduly nose—low position, which is conducive to waterlooping. It was the captain's theory that a wind shift, preceding the rain squall which hit the ship shortly after the landing was completed, caused the night wing to drop just as the ship was setting off the step. On the other hand, Pan American attributes the accident to the raising of the flaps during the run on the step, causing a slight change of altitude and a momentary period of directional instability beyond the power of the rudder to counteract. As a result, the company has ordered the practice of raising the flaps during that stage of the landing discontinued. The damage was localized in the right pontoon.