I invite you to watch as the sleek midnight blue and white aircraft designated “Yoke Yoke” (above) glides in for a landing on runway 15/33. The four de Havilland Ghost turbojet engines cradled within the wings are throttled back to idle, as 38 year old South African Airways Captain William Mostert gently sets the 100,000 pounds of aluminum alloy, wires, rubber tubing, kerosene ambitions and 21 souls onto the asphalt. It is 4:36 pm on the cool evening of Wednesday, 7 April, 1954. As the twin four-wheeled bogies of “Yoke Yoke”s landing gear absorb the impact, the crew and passengers of Flight 201 have less than 25 hours and 30 minutes to live. (https://www.youtube.com/watch?time_continue=320&v=vkMHJmkx6E8&feature=emb_logo)
There were warning signs before the de Havilland Comet Yoke Yoke landed at Rome's Ciampino Airport, completing the first leg of a flight ultimately headed for Johannesburg, South Africa. And although the Comet bore the colors and logo of the British Overseas Aircraft Corporation, the flight and crew were a South African Airways operation.
The strain of the shut down after the crash of Yoke Peter, and the 60 recommended repairs, were forcing de Havilland to miss production commitments. There was no Comet 1 available for this scheduled SAA flight. And since the Comets leased to South Africa, Air Canada and Air France produced needed foreign currency, de Havilland and the government convinced BOAC to charter Yoke Yoke to SAA for the flight. It was a jury rigged, temporary fix to the Comet's problems.
But the problems ran deeper. SAA flight 201 was supposed to be on the ground in Rome for an hour -just long enough to refuel. However no matter how much fuel they put in Yoke Yoke's center fuel tank, the gauge refused to move. The flight was delayed while the engineers searched for the source of the problem.
After draining the central tank, by elimination, it was assumed the co-axial cable running from the wing tank to the gauge was faulty. Which is when it was discovered that neither SAA nor BOAC Ciampino had a replacement cable in stock. A new cable would have to flown out from London, requiring Yoke Yoke to remain overnight in Rome.
That was mildly embarrassing, especially since de Havilland and BOAC were proudly declaring their primary advantage over piston engines was that the turbines of a jet required far less maintenance. In fact the entire industry was already moving from “maintaining” an aircraft at each stop, toward merely providing “service” - meaning only major transportation hubs would keep a collection of parts and mechanics. And the fuel indicator cable had not been considered to be essential. Oh, well. Part of the learning curve. So the passengers were put up in a hotel, and while waiting for the replacement cable it was decided to drain and inspect all the fuel tanks, just in case some thing else was the real problem.
And that was when they found, rolling around in the empty left wing tank (above) of Comet Yoke-Yoke, 22 quarter inch bolts. A panicked phone call to London eventually produced an answer to the mystery of what they were doing there. Nine days earlier, 52 bolts had been removed during a routine check of the tank. For some reason only 30 of those had been restored before resealing the tank. People were going to be fired over that mistake. But it got worse. While double checking all of the bolts, it was discovered that even the remaining 30 had not been fully tightened. For nine days the port wing tank had flown with less than half the structural support it was designed to have. The only thing which saved Yoke Yoke on all the flights during those nine days had been the redundancy de Havilland designed into the Comet. It had been a damn close call.
So, 25 hours late, on Thursday, 8 April, 1954, Comet Yoke Yoke left Ciampino airport bound for Heliopolis Airport, just east of Cairo, with a crew of 7 and 14 passengers. Five minutes after take off, at 5:37pm Central European Time, Yoke Yoke reported passing over the Ostia coastal beacon, 30 miles west southwest of Rome, at 7,000 feet.
At 5:49pm, the Comet reported passing over the island of Ponza, 75 air miles from Rome, and climbing through 11,600 feet. Twenty-five minutes after take off, at 5:57pm, Yoke Yoke reported they were abeam with Naples, having covered 118 miles by air. They were now approaching their cruising altitude of 35,000 feet. At 6:07pm CET, Yoke Yoke contacted Heliopolis and reported their Estimated Time of Arrival in Alexandria would be 9:02pm. Some time after that broadcast, Comet Yoke Yoke simply disappeared. No one saw or heard an explosion. No one saw the debris fall from the sky. The plane simply vanished.
Such a loss was not uncommon at the time, even with a reliable workhorse like the Douglas Commercial dash 4, of which over 1,200 were built between 1943 and 1949. On Thursday, 26 January, 1950 a U.S. military DC-4 (above) disappeared over the Yukon Territory, Canada, with 44 souls aboard. Despite a 2 month long search involving 85 Canadian and American aircraft and 7,000 personnel, no wreckage has ever been found, and no cause ever determined.
On the morning of 23 June 1950, Northwest Airways flight 2501, with 58 souls on board, disappeared over Lake Michigan. After a six week investigation, the cause was listed as “unknown”.
On 21 July, 1951 a Canadian Pacific Airlines DC-4 (above) carrying 27 souls, disappeared south of Anchorage, Alaska. No wreckage has ever been found. The cause is listed as “...not determined." It was not that pilots and engineers lacked curiosity, but rather that no one had yet designed a recording device which could survive a crash violent enough to kill passengers and crew. But it was coming.
Independently in 1953 both David Ronald de Mey Warren with Defense Science and Technology Organization, in Melbourne, Australian,...
...and Professor James Jay "Crash" Ryan, at the University of Minnesota, U.S. - who also invented the automobile retractable seat belt - ...
...designed wire recording systems which would note engine temperatures, fuel flow, aircraft velocity, altitude, control surfaces positions, and rate of descent, and could survive a crash. From the beginning it was decided to put these “black boxes”, aka Flight Data Recorders, in the tail, since, as one designer put it, “I never saw an airplane back into a mountain.”
Ryan got a U.S. Patent in 1953, but Warren's work got quicker attention from the industry, specifically in 1958 from Sir Robert Hardingham, then Secretary of the British Air Registration Board. Hardingham was interested, in large part, because of the Comet crashes.
Then, on 4 June 1967 a British Midland DC-4 (above), with 84 people on board, crashed in a suburb of Manchester, England. The captain was one of the 12 survivors, but he had no memory of the events just preceding the crash.
Luckily, however, the now required “black box” did remember. All DC-4's had 8 fuel tanks and a complicated plumbing systems to keep the aircraft balanced during flight. This crash – and perhaps earlier ones - had been caused because the cockpit fuel line controls were complicated and difficult to operate. In effect, the crew had chosen an almost empty fuel tank for the 2 right side engines, and during landing approach they both abruptly lost fuel and power. The aircraft flipped over and spun into the ground,
However the box also showed the desperate pilot retained just enough control to prevent the plane from slamming into homes. No one on the ground was killed.
But on Friday, 9 April, 1954, the search planes could find nothing left from Comet Yoke Yoke except an oil slick and five bodies floating in the Mediterranean. By the time ships arrived, even these were gone.
The next day the New York Times would report, “ “Britain today weighed the cost of a stunning blow to her proudest pioneer industry – jet civil aviation – as the crash of another Comet airliner was confirmed. Twenty-one persons, including three Americans, were believed to have died when the plane was lost in the Mediterranean...Tonight the Minister of Transport, A. T. Lennox-Boyd withdrew from all Comets the certificate of airworthiness... Sir Miles Thomas, chairman of the airline, said the new crash was 'a very great tragedy and a major setback for British civil aviation.'”:
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