Boeing’s twin disasters involving its newest single-aisle jet add to the history of rare aviation accidents that call into question the safety of the planes themselves. Back-to-back incidents where the aircraft is probed as a possible culprit are far less common than the usual litany of pilot error, mechanical failure, weather, war and terrorism. In the modern era, at least, that’s because manufacturers can draw on decades of experience and face rigorous reviews before new models are cleared to carry people. Swift regulatory intervention also can help blunt the risk of repeat accidents from the same cause. Hong Kong bans Boeing 737 MAX from airspace following Ethiopia crash While investigators are still piecing together the latest Boeing 737 MAX crash in Ethiopia , the initial similarities with the I ndonesia disaster in October - rapid pitching and dropping of the nose after take-off - stirred immediate speculation into a connection involving the plane’s design. The MAX is the latest variant of Boeing’s 737, a short-haul workhorse that is the world’s most widely flown jetliner . The De Havilland Mystery The saga of the De Havilland Comet from the dawn of the jet age is among the best-remembered examples of troubled plane design and recurring tragedies. The four-engine jet entered commercial service in 1952, shrinking the world for travellers less than three decades after the first solo transatlantic flight. Lurking within the groundbreaking British plane were the seeds of trouble: flying at 25,000 feet (7,600 meters) and more, and speeds topping 450 miles per hour, the Comet’s hull was subject to stresses never experienced in a passenger aircraft. In 1953, a BOAC Comet broke up in mid-air over India, killing all 43 people on board. In 1954, another Comet flown by BOAC disintegrated en route to London from Rome. All 35 people on board died. As the trade war heats up, Beijing looks to make its aerospace less reliant on other countries Grounded for inspections, the planes were flying again months later - only to be followed by another in-flight airframe failure that killed the 21 passengers and crew members on a South African Airways Comet heading to Cairo from Rome in April 1954. “The cost of solving the Comet mystery must be reckoned in neither money nor manpower,” Prime Minister Winston Churchill declared, fretting over the risks to the nation’s plane making prowess. The eventual verdict: metal fatigue built up over repeated pressurisation until the planes exploded at high altitudes with bomb-like force. Three successive redesigns failed to restore public confidence. “Fewer than 70 were ever built for airline service,” the Smithsonian magazine summed up in a 2002 history of the plane. The DC-10 McDonnell Douglas, a planemaker later acquired by Boeing, had its entire DC-10 fleet grounded in 1979 by the US Federal Aviation Administration after an American Airlines jet lost an engine on take-off, ripping out crucial hydraulic lines. All 271 people on board were killed. Inspectors found wing damage in other models. Regulators allowed the plane to be flown and a decade later, 111 people died on a United Airlines DC-10 after catastrophic hydraulic damage suffered when the rear engine failed. That crash was recalled for the heroics of the crew in minimising the loss of life - miraculously, 185 survived - as they wrestled the plane to the ground. The DC-10 made its last passenger flight in 2017, CNN reported. Boeing’s Dreamliner Boeing is no stranger to new models plagued by teething difficulties. US and European regulators moved promptly to ground Boeing’s 787 Dreamliner in 2013 to investigate battery fires. Authorities already were on alert for electrical woes in a model that suffered an in-flight blaze during flight tests more than two years earlier. While no one was killed in the Dreamliner’s battery incidents, the circumstances spooked the flying public. In one instance, a battery fire broke out on a parked Japan Airlines 787. In another, pilots had to set down an ANA Dreamliner after an in-flight warning and the smell of smoke. Boeing got the plane flying again in less than four months following a redesign of crucial battery components.