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By David Gero
The History PressCopyright © 2013 David Gero
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Commercial aviation truly came of age in the 1950s. The air travel boom that had begun shortly after the Second World War, introducing to the average person that which previously had been available only to those wealthy and daring enough to step on to an aeroplane, was in full swing. More flights were available to more destinations, with airliners carrying more passengers at greater speeds and higher levels of safety and comfort than ever before.
A number of larger and higher-performance aircraft saw their first passenger service in the 1950s. These included the Douglas DC-7 and Lockheed Super Constellation, which represented the peak in piston-engine transport development. In 1952 the de Havilland Comet introduced the first jet passenger service. The aircraft had to be withdrawn from use only two years later due to a serious structural deficiency, but the new refined Comet would return in 1958, providing the first jet airliner service across the Atlantic. It was joined by such jets as the French Caravelle and US Boeing 707; the latter would serve for many years as the backbone of long-haul air transport. Also introduced durng this period were several models of propeller/turbine aircraft, or turboprops, including the Vickers Viscount, Bristol Britannia and Lockheed Electra.
One of the most notable safety advances coming into operation in the 1950s was airborne weather radar. But of course the increased passenger-carrying capability of an aircraft would mean more casualties in the event of a crash, and, indeed, in 1956 commercial aviation suffered its first disaster to claim more than 100 lives when two transports collided over the Grand Canyon. Concern over air traffic control would cloud the industry throughout the latter half of the decade and into the 1960s.
Date: 12 March 1950 (c. 14:50)
Location: Near Sigginstone, South Glamorgan, Wales
Operator: Fairflight Ltd (UK)
Aircraft type: Avro 689 Tudor V (G-AKBY)
The airliner was on a charter service, carrying Welsh rugby fans home from Dublin, Ireland, where they had watched their team defeat the Irish in an international match. During its approach to land on Runway 28 at Llandow Airport, located some 15 miles (25 km) west-south-west of Cardiff, the four-engine transport assumed a glide path that gave eyewitnesses the impression that it would touch the ground prematurely.
While at an approximate height of 100 to 150 ft (30–50 m), a small increase in power was noted, which slightly reduced the aircraft's descent rate. This was followed by the sudden application of full power and, concurrently, by its nose pitching up. Climbing to about 300 ft (100 m), the Tudor stalled, then plunged into a field some 2,500 ft (750 m) from the threshold of the runway at a steep angle and on its right side, and with its undercarriage and flaps extended. There was evidence that the ignition had been switched off before impact, which may have accounted for the absence of a post-crash fire. All but three passengers among the 83 persons aboard were killed, including the entire crew of five; the survivors suffered injuries. The weather on this Sunday afternoon was good, with a visibility of 15 miles (c. 25 km) and westerly winds blowing at 10 to 15 knots.
An investigative court found that due to an inadequate amount of baggage placed forward in relationship to the passenger load, the aircraft's centre of gravity was at least 9 ft (2.7 m) aft of the specified limit. This probably resulted in insufficient elevator control remaining to counteract the rise of the nose upon the application of full power at a velocity that, while well above the stalling speed, was low enough to create a condition of acute instability. The court also regarded as unsatisfactory the loading instructions pertaining to the Tudor V, which did not contain adequate directions in determining how passengers and their luggage should be distributed. It said that the system then in use placed an unduly heavy burden of responsibility on the pilot.
For the trip to and from Dublin, there had been an alteration in the seating arrangement of the aircraft to allow for six more passengers than the maximum permissible, and this had required amending its certificate of airworthiness. However, the loading of the transport was not in compliance with the provisions of this amendment. For its violation, Fairflight was fined £50, plus an additional £150 to cover court costs.
The court recommended that whenever an aircraft's seating arrangements were to be changed, a new 'daily certificate' and 'technical log' should be prepared, and that it should be the function of the maintenance engineer responsible for the alterations to record in these documents the relevant information for reference by the pilot, with a provision for cross-checks.
Date: 24 June 1950 (c. 00:25)
Location: Lake Michigan, US
Operator: Northwest Airlines (US)
Aircraft type: Douglas DC-4 (N95425)
Operating as Flight 2501, the aircraft crashed into the great lake some 20 miles (30 km) north-north-west of Benton Harbor, Michigan, while en route from New York, New York, to Minneapolis, Minnesota, the first segment of a domestic transcontinental service destined for Seattle, Washington. All 58 persons aboard (55 passengers and three crew members) perished.
The DC-4 was last reported cruising in the early morning darkness at 3,500 ft (c. 1,050 m) after a request for descent to 2,500 ft (c. 750 m), which the crew made for no reason, had been denied due to conflicting air traffic in the area.
Subsequently recovered from the surface of the water were such light debris as cabin furnishings and personal effects. The bottom of the lake was 150 ft (c. 50 m) below the surface and covered by a layer of silt and mud estimated to be 30 to 40 ft (c. 10–12 m) thick, and despite a search using divers and sonar equipment, the main wreckage could not be located.
It was known that the disaster occurred shortly after the aircraft entered the area of severe turbulence associated with thunderstorm activity, which probably resulted in either structural failure or a loss of control, but there was insufficient evidence to determine which one of these possibilities actually caused the crash.
The forecast of a squall line in the area had been issued 1 hour 40 minutes before the accident, but this information was not made available to the flight.
Date: 31 August 1950 (c. 02:00)
Location: Near Wadi Natrun, Egypt
Operator: Trans World Airlines (TWA) (US)
Aircraft type: Lockheed 749A Constellation (N6004C)
Flight 903 took off from Farouk Airport, serving Cairo, bound for Rome, Italy, one segment of a service originating at Bombay, India, with an ultimate destination of New York City. About 20 minutes later ground witnesses observed the aircraft to be on fire. Subsequently it crashed and burned some 65 miles (105 km) north-west of the capital city, and all 55 persons aboard (48 passengers and a crew of seven) were killed.
The accident was attributed to the failure of the rear master rod bearing in the Constellation's No. 3 power plant, which caused the rear crankpin to overheat and collapse. This condition allowed the piston strokes to increase until the pistons began to strike the valves and cylinder heads. All the rear articulated and rear master rods then failed and sliced through the walls of the rear row of cylinders, tearing away a section of the crankcase. In turn, the fire seal was distorted and displaced. The general breakage was so widespread that oil lines were severed, and the release of the inflammable fluid and its fumes led to the fire.
Intensifying after the aircraft had turned back towards Cairo, the blaze ultimately melted the adjoining dural structure rearward of the firewall, causing the involved engine (whose propeller had been feathered) to fall free. Numerous other parts also separated as the fire burned through the top skin of the starboard wing.
Unable to reach the airport, the crew apparently attempted a forced landing on a desert plain in the early morning darkness, and while still under control the Constellation struck the ground in a slight nose and right wing-low attitude, with its undercarriage and flaps retracted.
There was a distinct possibility that sludge that had built up within the crankpins had broken away and obstructed the flow of oil, resulting in the master rod bearing failure. Because of this accident and other master rod bearing failures in the same model of Wright engine, several corrective measures were taken. These included more frequent oil changes, improved oil screens and the development of a crankpin plug to reduce sludge accumulation.
Date: 13 November 1950 (c. 18:00)
Location: Near Corps, Rhône-Alps, France
Operator: Curtiss-Reid Flying Services Ltd (Canada)
Aircraft type: Douglas DC-4 (CF-EDN)
The airliner was on a charter service from Rome, Italy, to Montreal, Canada, with a planned stop at Paris, France, when it struck de l'Obiou Peak, in the Devoluy range of the Alps, some 30 miles (50 km) south of Grenoble. All 58 persons aboard perished, including seven crew members; its passengers were Catholics returning home from a pilgrimage to the Vatican.
At the time of its crash at an elevation of 9,000 ft (c. 2,700 m), CF-EDN had been approximately 55 miles (90 km) to the east of, but flying at the altitude selected for, the normal route. Although the aircraft disintegrated in a flash fire on impact, there was no sustained blaze. The accident occurred in darkness and, reportedly, cloudy weather conditions.
Factoring in the error of navigation was the apparent misidentification of landmarks, including the town of Gap for Montelimar. The pilot probably realised the deviation and was attempting to take corrective action when the DC-4 hit the mountain.
Date: 30 June 1951 (c. 02:00)
Location: Near Fort Collins, Colorado, US
Operator: United Air Lines (US)
Aircraft type: Douglas DC-6 (N37543)
All 50 persons aboard (45 passengers and a crew of five) perished when the aircraft, designated as Flight 610, crashed some 50 miles (80 km) north-north-west of Denver, where it was to have landed during a domestic transcontinental service from San Francisco, California, to Chicago, Illinois, its last scheduled stop having been at Salt Lake City, Utah.
Following passage of the Cheyenne radio range station, the DC-6 was to have turned right and headed south towards Denver. Instead, the turn was well in excess of 90 degrees, which placed it on a south-south-westerly heading. Flying in darkness, the cleanly configured aircraft continued in this direction until it struck cloud-obscured Crystal Mountain at an approximate elevation of 8,500 ft (2,600 m), disintegrating on impact. Despite some localised fires, there was no major post-crash blaze.
It could not be determined why the flight had not followed the prescribed airway. One plausible theory was that the captain had depressed the wrong toggle switches on the aircraft's audio selector control panel (this could have happened in the darkened cockpit, especially considering that the switches were not obvious and were usually activated by feel). As a result, he may have silenced the signals of the Denver low-frequency radio range, whose beam demarcated the proper track, but allowed receipt of the Denver visual aural range (VAR) signals. This radio range, which would only have been used by the crew to determine at what point the turn should be initiated, ran roughly parallel to the low-frequency range, and its signals were such that they would be difficult to differentiate.
It was also considered possible that the pilot had tuned his automatic direction finder (ADF) in such a way that it had been affected by the radio range station at Fort Bridger, Wyoming.
The US Civil Aeronautics Administration (CAA) later took action to eliminate confusion between the Denver and VAR ranges. Meanwhile, the carrier modified its audio selector panels to prevent a possible mistake in switch selection, and also implemented a programme with a particular emphasis on route training and equipment qualification for its crews.
Date: 24 August 1951 (c. 05:30)
Location: Near Union City, California, US
Operator: United Air Lines (US)
Aircraft type: Douglas DC-6B (N37550)
Flight 615 had been cleared for a straight-in landing approach to Oakland Municipal Airport, a scheduled stop during a domestic transcontinental service destined for nearby San Francisco, which originated at Boston, Massachusetts. Descending in twilight through a broken layer of stratus clouds, with a base of about 1,500 ft (500 m), and in patches of fog that obscured the terrain, the aircraft crashed some 15 miles (25 km) south-east of the airport. All 50 persons aboard (44 passengers and six crew members) perished in the disaster.
Although the DC-6B was to have proceeded along the Oakland radio range course, neither of its two low-frequency receivers were tuned to the station. Instead, the captain had deviated from the prescribed instrument procedures, and may have attempted to fly by visual reference, using the first officer's automatic direction finder (ADF) to maintain the proper course. As a result the flight was approximately 3 miles (5 km) to the right of the on-course beam and well below the minimum prescribed altitude of 3,500 ft (c. 1,050 m).
Its main undercarriage down and flaps either retracted or partially extended, the aircraft struck a hill at an elevation of about 1,000 ft (300 m), or less than 30 ft (10 m) below its crest, while on a north-westerly heading and at a ground speed of between 225 and 240 mph (c. 360–385 kmh), then disintegrated in a fiery explosion.
Subsequently, the carrier enacted a requirement that crews operate under instrument flight rules (IFR) when above an overcast, to assure adherence to minimum altitudes.
Date: 16 December 1951 (c. 15:10)
Location: Elizabeth, New Jersey, US
Operator: Miami Airline Inc (US)
Aircraft type: Curtiss C-46F (N1678M)
The twin-engine transport had just taken off from Newark Airport, on a non-scheduled domestic service to Tampa, Florida, when control tower personnel noticed smoke emanating from its right side. Although the tower controller cleared the crew for an immediate landing, the message was not acknowledged. At about the same time another ground witness, a Miami Airline captain, also observed N1678M trailing smoke. Believing that the source of the smoke was an overheated right brake, he telephoned the control tower, suggesting that the crew be instructed to extend the gear. The pilots, unfortunately, followed his advice.
Minutes later, the C-46 began a gradual descending left turn, its starboard propeller still windmilling. Suddenly, its port wing dropped, and the airliner struck the roof of a house and a building, then crashed in the Elizabeth River. The wreckage, which had come to rest largely inverted in the shallow water, then erupted into flames. All 56 persons aboard were killed, including a regular crew of three and an off-duty airline employee riding as a passenger, who was not on the manifest. Additionally, one person on the ground was seriously injured.
The accident was ascribed to faulty maintenance procedures by the airline. Examination of the right power plant revealed that the 15 hold-down studs on the No. 10 cylinder had failed from fatigue due to improper installation of their securing nuts. This caused the cylinder to separate completely from the crankcase during or shortly after take-off.
The fire that erupted in the base of the failed cylinder could have resulted from several sources of ignition, including a continuous egress of both liquid and atomised lubricating oil, a connecting rod that had broken and was flailing, or from opened exhaust or inlet ducts. Activation of the fire-extinguishing system failed to check the blaze, and it ultimately burned through lines carrying fuel, oil and hydraulic fluid, and through the closed doors of the right wheel well. And when the undercarriage was lowered, the flames were allowed freer entry into this compartment, causing even more damage. The gear extention would also have increased drag, and this, coupled with the power loss, the inability of the crew to feather the right propeller (probably because the fire had destroyed an electrical or oil line) and the fact that the transport was loaded by nearly 120 lb (c. 55 kg) above its maximum allowable gross weight, caused a stall at a height of about 200 ft (60 m), which led to the crash.
Numerous violations by the carrier over a period of 3 ½ years, most involving the overloading of aircraft, were noted in the investigative report of the US Civil Aeronautics Board (CAB). Additionally, inadequacies were identified in the method by which the airline trained its pilots in the area of emergency procedures, and this could have had a bearing on what appeared to be a delay in such action being taken by the crew of N1678M.
A completely redesigned nacelle, which incorporated new fire protection devices, would later be developed by a private company for use on the C-46.
Date: 11 April 1952 (c. 12:20)
Location: North of San Juan, Puerto Rico
Operator: Pan American World Airways (US)
Aircraft type: Douglas DC-4 (N88899)
Excerpted from Aviation Disasters by David Gero. Copyright © 2013 David Gero. Excerpted by permission of The History Press.
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