Boeing 377 crash in the Pacific

The Boeing 377-10-26 Stratocruiser with the serial number 15959 and serial number 36 was released by the Boeing Airplane Company in 1949 and on August 2 of the same year made its first flight ^[2] . Airliner handed over to the customer - the airline American Overseas Airlines (AOA), where he received the registration number N90943 and was first named Flagship Holland ( Russian “ Flagship Holland” ), but was later renamed Flagship Europe ( Russian “Flagship Europe” ). However, in 1950, AOA was absorbed by another airline, Pan American World Airways, in connection with which the board of the N90943 moved to the fleet of the latter, where it received the name Clipper Sovereign Of The Skies ( Russ. Alaska Branch ^[3] . Its four power plants consisted of Pratt & Whitney R4360-B6 engines equipped with propellers firm Hamilton Standard model 24260 (blades - model 24260-43 / 2J17). During the entire period of operation of the aircraft, its engines and blades were timely serviced in accordance with established methods; the total operating time of the N90943 board was 19,820 hours 51 minutes ^[4] .

The flight on October 16, 1956 served the following crew ^{[4] [5]} :

• The commander of the aircraft (FAC) - 43-year-old Richard N. Ogg ( born Richard N. Ogg ). He worked in Pan American since February 20, 1941, the last medical commission of the Civil Aviation Committee was held on September 21, 1956, and classes on the use of rescue equipment - on June 4, 1956. His total flight time was 13,089 hours and 41 minutes, including 738 hours and 27 minutes on B-377 aircraft.
• The co - pilot is 40-year-old George Lee Haecker ( born George Lee Haaker ). In Pan American, he worked from March 1, 1946, the last medical commission of the civil aviation committee was held on September 4, 1956, and classes on the use of rescue equipment - on August 2, 1956. His total flight time was 7576 hours, including 3674 hours and 6 minutes on B-377 aircraft.
• The navigator - 31-year-old Richard L. Brown ( English Richard L. Brown ). He worked in Pan American since December 9, 1955, on August 24, 1956 he received a temporary certificate of a civil aviation navigator, passed a medical commission of a committee of civil aviation on February 28, 1956, and initial training on the use of rescue equipment on January 13, 1956. His total flight time was 1283 hours and 16 minutes, including 446 hours on B-377 aircraft.
• Flight engineer - 30-year-old Frank Garcia Jr. ( Eng. Frank Garcia, Jr ). In Pan American he worked from August 16, 1954, he had certificates of a flight engineer, mechanic and radio operator , and on March 28, 1956 he received qualification for B-377; The last medical commission of the Civil Aviation Committee was held on June 29, 1956. His total flight time on B-377 aircraft was 1,728 hours.
• Flight attendants
  • 30-year-old Patricia Reynolds ( eng. Patricia Reynolds ) - the eldest stewardess. She worked in Pan American since September 23, 1946, on February 10, 1956 she was the last refresher on the use of rescue equipment on B-377, and on July 12, 1956 she was trained on the water at the USCG base in San Francisco.
  • 24-year-old Mary Ellen Daniel ( eng. Mary Ellen Daniel ). She worked in Pan American since June 23, 1954, on March 12, 1956 she underwent the last retraining on the use of rescue equipment on B-377, and on September 18, 1956 she was trained on the water at the USCG base in San Francisco.
  • Katherine S. Araki, 23, ( Katherine S. Araki ) She worked in Pan American since March 26, 1955, and on May 7, 1956 she was the last retraining on the use of rescue equipment on B-377.

Flight to San Francisco

Boeing 377 board N90943 operated a regular round-the-world flight 100/6, which began on October 13 in Philadelphia ( Pennsylvania ) and then headed eastward (estimated route: New York - London - Frankfurt - Beirut - Karachi - Rangoon - Bangkok - Hong Kong - Tokyo - Wake - Honolulu - San Francisco ). On October 15, the plane landed safely in Honolulu ( Territory of Hawaii ), after which the crew began to prepare to perform the flight PA-006 (the aircraft's call sign - Clipper 943 ) to San Francisco . The flight was supposed to take place on the IFR , while, according to the permit issued by the dispatcher, after the departure from Honolulu the plane was to be sent along the “Green 9” air corridor ( English Green Airway 9 ), then at a flight level of 13,000 feet (4000 m ) to the point , and after at echelon 21 000 feet (6400 m ) to San Francisco. A total of 24 passengers were on board, including 3 babies, and 7 crew members; there was a fuel reserve for 12 hours with an estimated flight duration of 8 hours and 54 minutes. Estimated gross take-off weight was 138,903 pounds (63,005 kg) with a maximum allowable 144,000 pounds (65,300 kg); alignment also did not go beyond the established limits ^{[6] [7]} .

According to the available information about the weather, the wind was quiet and the sky was clear with individual small clouds, the waves at the sea were 3-4 feet high (about 1 m), coming from the direction of 80 ° ^[8] .

At 20:26 ^{[* 2]} , almost an hour behind schedule ^[7] , with 31 people aboard the Boeing flew from Honolulu airport and, following the course of 62 ° ^[7] , normally collected an echelon of 13,000 feet, and at 01:02 on October 16, when half the flight took place, but before reaching the point of (its passage was estimated at 01:31), the crew requested and received permission for a visual flight with a climb to the echelon of 21 000 feet ^[9] .

Engine problems

Engine power was increased, and the airliner under the control of co-pilot Haaker began to climb, until at 01:19 it was leveled at a predetermined flight level. The flight speed increased to 188 knots (348 km / h), so the flight engineer Garcia reduced the power of the engines when suddenly the heavy car jerked, while the left wing sounded howling and the controls began to vibrate; Heeker, glancing at the instruments, saw that on the tachometer of engine No. 1 (leftmost) the speed jumped to 2900 min ⁻¹ , therefore he immediately pressed the propeller feathering button and also released flaps by 30 °. Garcia simultaneously activated the fire protection of this engine, shut off its choke, and also turned off the enrichment of the fuel mixture, after which it further reduced power in the other three engines in order to reduce the speed of flight; at this moment, the testimony on the tachometer of engine No. 1 has already begun to go off scale ^{[10] [11]} .

Commander Ogg, who had previously been at the navigator's desk, quickly took his place, and after several unsuccessful attempts to feather the engine working in a freelance mode, the flight engineer ordered the oil engineer to shut off the oil supply to the engine to disable it. After two or three minutes, the engine speed went down, then there was a strong thud, after which the propeller again accelerated to high speed. Working now in autorotation mode, the propeller No. 1 began to create aerodynamic drag, but stubbornly did not want to feather; since the number of revolutions in engine number 1 was zero, as was the oil level, the crew concluded that a failure occurred in the cardan mechanism, as a result of which the screw was disconnected from the engine ^{[10] [11] [12]} .

The air speed dropped to 150 kts (280 km / h), and the car began to decline at a vertical speed of about 1000 feet (300 m ) per minute, so at 01:22 the commander contacted the meteorological vessel November and reported on a possible dive, requesting assistance, to which they responded that the aircraft was observed on radar at a distance of 38 miles (61 km ) in an azimuth of 256 °; passengers, meanwhile, began to prepare for an emergency landing (instructions for its implementation were read before take-off). The course was changed to follow by November , and to reduce the rate of decline at 01:24, the power of the remaining three engines was increased, when the crew noticed another nuisance - engine No. 4 (far right) with full gas produced only part of the power, while the number of revolutions it was 2350 min ⁻¹ , and the other parameters were normal. Increasing the enrichment of the mixture to the maximum gave only a minor effect, therefore the number of revolutions in the fourth engine was reduced to 1750 min- ¹ , shutting off its oil cooler and intercooler , and closing the bonnet flap by half an inch ^{[8] [12]} .

Preparing for planting

At 01:25 the pilots reported to November that the landing was inevitable, in response to which they were sent to the patrol ship Pontchartrain located near the meteorological vessel US Coast Guard, whose captain was William Earl ( Eng. William Earle ) ^[1] . However, in the process of descending, the crew realized that the situation was not so hopeless, since with the nominal power of the second and third engines and the partial fourth, the airliner could support horizontal flight at a speed of 135 knots (250 km / h); the altitude at that moment was 5,000 feet (1,500 m ), but it was decided to go down to 3,000 feet (910 m ). The crew reported about the incident in Honolulu, while constantly keeping in touch with November , receiving from him fresh information on weather conditions and waves at sea. In the cabin, in the meantime, flight attendants asked passengers to take off glasses, shoes and remove sharp objects from their pockets, as well as put on life jackets , while having to improvise putting on vestlets designed for an adult on children; several passengers were instructed to deploy life rafts after landing. Passengers were also taken out of the tail section of the aircraft, since the commander believed that she could detach when hitting the water, and put the children on the floor ^{[8] [13]} .

At 01:37, the Boeing flew over November and Pontchartrain , while the crew determined that with the current configuration of the aircraft (flaps by 30 °, one screw in autorotation mode) it is possible to maintain horizontal flight at a speed not exceeding 140 knots (260 km / h ), which is about 20 knots (37 km / h) lower than the effective speed of flight on two engines. Considering the high aerodynamic drag and low airspeed, the maximum flight range for the current fuel reserve was estimated at 750 miles (1,210 km ), while the distance to San Francisco and Honolulu was over 1000 miles (1600 km ). When the liner, following the course of 240 °, flew over ships for the second time, the Pontchartrain team had already placed electric lights on the water line, and from the onboard mortar they additionally started to launch flares to mark and illuminate the landing area. However, the commander, assessing the situation, decided to postpone the landing until dawn, in anticipation of which he was circling nearby, which at the same time would help ease the plane by burning fuel; passengers were informed about this decision, after which a more thorough preparation for an emergency landing began ^{[8] [13]} . In anticipation of the morning, passengers were allowed to move freely around the cabin and even smoke ^[14] . As the passengers later recalled, this gave them confidence, since they understood that they were really preparing to help them at sea ^[1] .

At 02:45, engine number 4 failed with a drop in power (according to data from the analyzer, the engine had problems with ignition in a number of “B” cylinders), but its propeller No. 4 was flooded normally. The flight took place at an altitude of 2000 feet (610 m ) at a speed of 140 knots (260 km / h) and was now supported only by the remaining engines Nos. 2 and 3, which operated at a speed of 2550 min ^-1 , and the fuel consumption was 2,000 pounds (910 kg) per hour; later, when part of the fuel was consumed, the aircraft was able to climb to an altitude of 5000 feet (1500 m ), where the crew conducted a test of the aircraft’s controllability at low speeds ^{[13] [14]} .

Streamline

When it began to dawn, the coast guard officers removed the lanterns from the water and asked the pilots to warn about a landing in less than 10 minutes so that they could prepare an emergency rescue team on the ship. At sea at that time there were waves 2-3 feet high ( 0.6–0.9 m ), traveling at a speed of 13 knots (24 km / h) from a course of 130 °, atmospheric pressure 30.08 inches (764 mm) hg .st. The water temperature is 74 ° F (23 ° C) . At 05:40, an approximate landing time was reported from the Boeing, to which Captain Earl reported that the swell at sea was up to 5 feet (1.5 m ), and the northwest wind was 8 knots (15 km / h) ^[15] ; by 06:05 Pontchartrain of fire cranes over the ocean for 2500 yards (2300 m ) laid a foamy trail about 100 feet wide (30 m ) at a rate of 315 ° (against the direction of the waves) so that it was easier for pilots to determine the height above the water, and also to prevent spilled aviation fuel from igniting in the event of aircraft destruction ^{[6] [7] [14] [16]} .

At 05:50, the crew instructed passengers to occupy the prescribed seats, after which, dropping to 900 feet (270 m ), at 05:52, performed a test approach; at 06:05, the flight engineer discharged carbon dioxide cylinders into the wings to prevent a fire, and the commander warned passengers that the landing would be completed in 10 minutes. At 06:13 “Boeing” at a speed of 90 kt (167 km / h) and with fully extended flaps leveled off the water, after which the navigator with the flight engineer, at the direction of the commander, left the cabin and took seats in the cabin; next, the commander stopped the two remaining engines, after which he announced everyone in the cabin on the speakerphone to take safe poses - bending down and clasping his legs with his hands ^{[7] [14]} .

At 06:15, the N90943 board crashed into the Pacific Ocean. The first contact was weak, but then the left wing crashed into the wave ^{[3] [17]} , which caused a powerful blow, which turned the plane almost 180 °, as a result of which the tail section separated in the main exit area, thus breaking a row seats before the rift, several passengers thrown on the floor, and two babies flew out of their mothers. Raising a cloud of spray, the Boeing dug into the water, while people on the ships even thought for a moment that they had witnessed a catastrophe, and everyone on board died ^[1] , but after a second the airliner surfaced and, slightly moving forward, stopped. As a result of such a hard landing, the animals that flew in the cargo hold were killed: two dogs, a parrot and 3300 canaries (were placed in 44 boxes ^[18] ); none of the people was seriously injured, only 5 people received light injuries ^{[7] [14]} .

Immediately after stopping, both emergency exits were opened and two 20-seater life rafts were lowered through them. The raft on the port side did not completely sulk, which is why the water began to flood it, but all the people in it were rescued on time by a suitable rescue boat. The third raft was launched through the main exit, but was trapped between the wing and the broken off part, which drifted to the left of the plane, so savvy passengers dragged it along the wing to the first raft ^[14] . The last airliner left the commander Richard Ogg and senior stewardess Patricia Reynolds ^[3] . By 06:32 all 24 passengers and 7 crew members were aboard the Pontchartrain , and at 06:35 the Boeing sank at ^[16] .

In flight, allegedly independently of each other, two mechanical faults arose, and it was not possible to study the plane, since it was now lying on the ocean floor. In this regard, the entire investigation is now based on logical conclusions based on existing knowledge and experience ^[19] .

Engine number 1

The first thing the crew encountered was the excess of the number of revolutions in engine No. 1 and the failure of the feathering system of its propeller. The number of revolutions in the engine is maintained due to the pressure of oil, which is sent to the propeller regulator, where, by changing the angle of the blades, it regulates the rotational speed of the entire engine. The screwing of the screw, in turn, is carried out by an auxiliary oil pump, which takes the oil out of the supply reservoir, and then sends it to the screw regulator through the aisles of the speed maintenance system; Thus, a part of the propeller control system is used both for maintaining the speed and for feathering. There is a high probability that the malfunction that occurred first led to an overspeed of rotation, because if there had been a failure of the auxiliary oil pump earlier, then another malfunction had to occur in the propeller system, which is almost impossible. Since the increase in the angle of rotation of the blade, and hence the screwing of the screw, occurs by increasing the oil pressure under the piston of the regulating system, it is logical that the engine output at elevated revolutions and the failure of the feathering system occurred because the oil from the engine tank No. 1 stopped do without external signs of leakage. Most likely, the oil was mistakenly directed to the piston, which, on the contrary, reduced the angle of the blades, or there was no oil pressure at all. In the first case, the oil could be contaminated due to a defect in the engine design, and the pollution was progressive in nature and did not manifest in any way for the crew until the engine went to excessive speed. In the second case, there could be a large leakage through seals, passages, transfer tubes, screw bearings, screw or motor regulators ^[19] .

In the final report, the commission came to the conclusion that a failure occurred in the power plant, which had an impact on the part of the system that was common to maintain the speed and for feathering the propeller. The specific cause of the investigators could not determine. It was noted that after the accident in Pan American on the B-377 aircraft of the Pacific-Alaska Branch there were two more cases of uncontrolled increase in engine speed and failure of the propeller feathering system, and the cause in both cases was the failure of the floating propeller bearing; from March 25, 1957 on all these aircraft began to put floating bearings of a new design ^[19] .

Engine number 4

According to the crew, the pressure of the oil and fuel in the engine was normal, but the temperature and fuel consumption were low. Initially, a version was considered that the loss of power was caused by a reduction in the flow of air through the carburetor, which, in turn, could be caused by obstruction due to deformation or partial destruction and displacement of the duct system. In the course of further analysis, another version came to the fore - a failure of the impeller drive of the engine, which was favored by the data from Pan American, according to which prior to this accident, these engines already had three such failures, and the faulty engines had similar readings to engine No. 4 in this incident. At the same time, in one of the previous cases, the crew reported that a small reverse flashes occurred in the engine a minute before the failure, after which the screw of this engine was immediately threaded; on the contrary, in the incident of October 16, 1956, the engine worked at reduced power for some time before the failure. Кроме того, на Clipper 943 экипаж наблюдал по анализатору, что в ряду «B» цилиндров двигателя были проблемы с зажиганием, но эти данные не противоречат версии с отказом крыльчатки, так как с уменьшением подачи воздуха в двигатели снижается и расход топлива; в этом случае, предположительно, образовавшийся небольшой объём топливной смеси неравномерно распределился между цилиндрами, что и привело к отдельным проблемам в зажигании ^[20] .

Таким образом, наиболее вероятной причиной нарушения в работе двигателя № 4 , а затем и его отказа был назван отказ привода крыльчатки двигателя ^[20] .

Рассмотрение аэродинамического сопротивления

Самолёт Boeing 377 рассчитывался на выполнение безопасного полёта только с двумя двигателями, при этом рекомендуемая скорость была определена как 165 уз (306 км/ч); если бы у Clipper 943 были зафлюгированы оба винта отказавших двигателей, то он бы мог безопасно достичь американского побережья , либо вернуться на Гавайские острова . Однако в данном случае возникла ситуация, когда один из двигателей работал в режиме авторотации, создавая повышенное сопротивление, в результате чего возрос расход топлива. После событий с рейсом 100/6 компании Hamilton Standard и Boeing провели испытания, на данном типе самолётов и с данными силовыми установками, по определению аэродинамического сопротивления и мощности, необходимой для его компенсации. Полёты выполнялись на высоте 2000 футов (610 м ) со скоростью 145 уз (269 км/ч), а лопасти нерабочего винта были установлены на угол 21,3° ^[20] .

Так как сила сопротивления возрастает пропорционально квадрату скорости, то на скорости полёта выше 145 уз (269 км/ч) показатели будут уже гораздо больше. Результаты испытаний имели большое значение, так как ранее этот момент особо не рассматривали. До эксперимента была распространена гипотеза, что неподвижный воздушный винт создаёт куда меньшее воздушное сопротивление по сравнению с работающим в режиме авторотации, но испытания показали обратное. Стоит, однако, отметить, что данные величины были получены лишь на отдельных самолётах ^[21] .

Комиссия от Совета по гражданской авиации (CAB) пришла к мнению, что причиной происшествия стал первоначальный механический отказ, который не позволил зафлюгироваться воздушному винту № 1 , и последующий механический отказ, приведший к полной потере мощности в двигателе № 4 , последствия чего привели к необходимости выполнить приводнение ^[16] .

В 1958 году на экраны вышел кинофильм « Вынужденная посадка » режиссёра (умер в период монтажа фильма), основанный на происшествии с рейсом PA-006. В отличие от реальной истории, события фильма перенесены в Атлантический океан и происходят на борту современного на тот момент самолёта Douglas DC-7 , а на помощь вместо сторожевого корабля береговой охраны приходит эсминец американских ВМС . Основную роль в сюжете занимают переживания пассажиров и экипажа в ожидании рассвета, пока авиалайнер кружит над морем близ корабля, при этом многие герои переосмысливают свои отношения. Главные роли в фильме исполнили Гэри Меррилл (командир самолёта Стив Уильямс) и Нэнси Рейган (Хелен Уильямс, его жена), причём для Рейган это было последнее появление на большом экране. В титрах она указана под именем «Нэнси Дэвис» ^{[23] [24]} .

Приводнения Boeing 377

• Катастрофа Boeing 377 в Тихом океане
• Катастрофа Boeing 377 под Сиэтлом

Comments

Sources

• Pan American World Airways, Inc., Boeing 377, N90943 in the Pacific Ocean, between Honolulu and San Francisco, october 16, 1956 (англ.) . Civil Aeronautics Board (11 July 1957). Дата обращения 25 апреля 2018.
• Pan American World Airways, Inc., Boeing 377, ditched in the Pacific Ocean between Honolulu, Territory of Hawaii and San Francisco, California on 16 October 1956 (англ.) // ICAO Accident Digest № 8 : ICAO Circular 54-AN/49. — Montreal: Международная организация гражданской авиации , 1958. — May. — P. 133—137 .