16th of October 1956
Updated: Oct 16, 2021
It was on this day in aviation history that Pan American World Airways flight 6 was forced to ditch in the Pacific Ocean on its flight from Honolulu to San Francisco. The last leg of an around flight in the Boeing Model 377 Stratocruiser named 'Sovereign of the Skies', with registration N90943.
The Boeing 377 Startocruiser ditching in the Pacific Ocean on this day in 1956.
The aircraft took off from Honolulu Airport at 08.24 (local time) in the evening for its 8 hours and 54 minutes flight to San Francisco. The crew had the aircraft fueled with enough fuel for 12 hours and 18 minutes. Just over 4 1/2 hours into the flight the aircraft was cleared for its step climb to 21.000 feet, this was roughly at the Equal Time Point of the flight. (Equal TimePoint is also known as the Point of No Return) When reaching their new cruising altitude the crew reduced the engine settings from a climb setting to a cruise setting. It was at this point that the slices of Swiss Cheese started to line up. The propellor governor for the #1 Engine (Lefthand outboard) failed and the propellor became uncontrollable. As it began to Overspeed and actually exceeding the maximum indication of the tachometer. Attempts t to feather the #1 propellor also failed. All attempts to regain control of the engine and APU were without result. This left them with only 1 option, shut the engine down by stopping the oil supply to the engine, seizing it and hopefully stopping the propellor. The engine stop, but the propellor would continue to spin.
Pan American World Airways’ Boeing 377 Stratocruiser, Sovereign of the Skies, wreckage floating in the Pacific.
With the unfeathered engine, the drag was so large that the remaining engines had to run at high power to keep the aircraft at its cruise altitude. Just over an hour after the #1 propellor and # engine issue, the number four (Right-hand outboard) engine started to run down and only delivered partial power at full throttle. Eventually, it started to backfire and had to be shut down. With only two engines running they were not able to maintain altitude and started to drift down towards the ocean. With the speed down to only 140 knots, both Honolulu and San Francisco were out of reach even with 3 hours and 24 minutes of extra fuel. To assist all air and sea traffic the US Coast Guard had a ship stationed in the Pacific, at a position known as Ocean Station November. They would now be the lifeboat for the passengers and crew of Pan American World Airways flight 6.
The USCGC Pontchartrain (WHEC 70), that was at Ocean Station November that faithfully day in 1956.
Realising they were unable to reach land, the crew contacted the Coast Guard ship and told them about their intentions to ditch the aircraft. After circling for some time waiting for daylight, at 6.15 in the morning. the Boeing 377 was gently lowered onto the waves with a speed of about 90 knots (104 mph / 167 kph). When a wing hit a wave, the aircraft spun to the left and while the aircraft settled the tail broken off.
All passengers and crew evacuated the aircraft and only some minor injuries were sustained. As they ditched close to the Coast Guard ship all occupants were taken on board by the lifeboats of the Coast Guard ship and safely transferred to the ship. Twenty minutes after ditching the wreckage sank to the bottom of the Ocean The only casualties were 44 canaries, The wreckage of the aircraft sinking that were part of the cargo. The US Coast Guard later published a 10-minute film with actual images from the ditching with voice-overs re-enacting the communication between the ship and the aircraft. Click here to see that movie on youtube.
Boeing 377 Stratocruiser N90943, Pan American World Airways’ Sovereign of the Skies, seen over San Francisco, circa 194
Some specifications for a Boeing 377 Stratocruiser. General characteristics
Crew: 4 flight crew + cabin crew
Capacity: Up to 100 passengers on the main deck plus 14 in lower deck lounge; typical seating for 63 or 84 passengers or 28 berthed and five seated passengers.
Length: 110 ft 4 in (33.63 m)
Wingspan: 141 ft 3 in (43.05 m)
Height: 38 ft 3 in (11.66 m)
Wing area: 1,769 sq ft (164.3 m2)
Empty weight: 83,500 lb (37,875 kg)
Max takeoff weight: 148,000 lb (67,132 kg)
Powerplant: 4 × Pratt & Whitney R-4360-B6 Wasp Major 28-cylinder air-cooled radial piston engines, 3,500 hp (2,600 kW) each
Propellers: 4-bladed constant-speed fully-feathering propellers
Maximum speed: 375 mph (604 km/h, 326 kn)
Cruise speed: 301 mph (484 km/h, 262 kn)
Range: 3,600 nmi (6,800 km, 4,200 mi)
Service ceiling: 32,000 ft (9,800 m)