The fissure, discovered in an aircraft flown by budget carrier Southwest, is at the center of a new air safety scandal. The US airline has faced criticism for not conducting mandatory inspections on some of its planes.
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The US aviation regulator says it has launched an investigation after a 12-inch (30.5cm) crack ruptured the skin of a Boeing 737 aircraft operated by Southwest Airlines, causing the plane to gradually lose cabin pressure.
The Federal Aviation Administration (FAA) stepped in on Friday after a plane gradually lost cabin pressure during a flight from Las Vegas to Boise, Idaho.
Flight records revealed that the pilots began a rapid, six-minute descent from 39,000 feet (990 meters) to 22,000 feet. No injuries were reported from the incident, on Monday, and the cabin pressure was safe at the lower altitude, the agency said.
The ultimate passenger plane entered commercial service 50 years ago with a Pan Am flight from New York's Kennedy Airport to London's Heathrow. Though the original flight was delayed one day, it ushered in the jet age.
Image: picture-alliance/dpa/M. Reynolds
A wide-body wonder
Though its maiden flight was on February 9, 1969, the Boeing 747 actually entered commercial service nearly a year later with a Pan Am flight from New York to London. This first flight was originally scheduled for the 21st, but was delayed due to mechanical problems. With a nearly seven-hour delay — and replacement plane — history was made when on January 22, 1970 the 747 took off at 1:52 a.m.
Image: Getty Images/AFP
A fabulous interior
The first Boeing "jumbo jet" had a list price of $23 million according to contemporary reports. It was a true American invention and was assembled just outside Seattle in Everett, Washington, had 11 doors and room for up to 362 passengers. But it was the amazing roomy interiors with high ceilings that captured the imagination of travelers from around the world and made it so special.
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Glamour in the skies
Within a month of its first flight, Pan Am added more flights connecting San Francisco, Los Angeles, Tokyo and Hong Kong. Soon other international airlines rolled out their own 747s. By June 1970, Boeing had orders for nearly 200 of the aircraft. The comfortable planes attracted the rich and famous. Here Gloria Swanson is seen in the 1974 disaster film "Airport 1975" also staring Charlton Heston.
Image: Imago Images/Universal Pictures/Mary Evans
Designing for the blue beyond
At the time not everyone was sold on the idea. Many feared there was no market for such a large plane and that it would be impossible to sell so many tickets to fill all the seats. Others worried that airports were unfit to handle the increased number of passengers all at once; how could so much luggage be loaded and unloaded? Still Joseph Sutter, head of the 747 design team, stuck to his plans.
Image: Elaine Thompson/AP/picture alliance
Powered by four turbofans
To start the "second jet age" the new 747s needed to be big, but also powerful. Its four engines were not made by Boeing but by Pratt & Whitney, a subsidiary of United Aircraft Corporation. They were the most powerful jet engines ever produced up until that time and generated an amazing 46,000 pounds of thrust to propel it 600 miles an hour — just what was needed for long transatlantic flights.
Image: Getty Images/AFP/T. Schwarz
Is bigger always better?
At first most airports were not prepared for such a massive jet, one that was well over twice the size of the Boeing 707. Runways needed to be lengthened and reinforced for the plane's 350 tons. Others needed to invest millions in new, bigger check-in areas, more waiting room and baggage capacity. One consequence of bigger planes was the entrenchment of the hub-and-spoke model for airlines.
Image: Fabrice Coffrini/AFP/Getty Images
The most famous 747
Air Force One, the American president's wings, is the most famous 747 to ever take off. In reality two 747-200s, the aircraft is only called AFO when the president steps onboard. Delivered in 1990, the planes are specially equipped and can be used as a flying White House. Though their paintjob is instantly recognizable, they are soon to be replaced with new 747-8s at a cost of over $3 billion.
Image: Reuters/J. Urquhart
An icon through and through
Over the years the plane has gone through updates. Gone are the bars and many of the other luxuries that once filled parts of the jet like grand pianos. Versions were lengthened and seats were reconfigured. The 747-400 can squeeze in 524 passengers. Still airlines looked elsewhere. In the US Delta was the last company to fly the passenger giants and even they retired the last one in December 2017.
Image: picture-alliance/dpa/M. Reynolds
A slow decline
In other parts of the world, the 747 is still in commercial service. British Airways has the largest fleet in operation. Yet slowly but surely after years of setting passenger records, the original jumbo jet also known as the "Queen of the Skies," has continued to fall out of favor compared with newer, more fuel efficient planes. In the last decade orders have been low even for cargo versions.
Image: picture-alliance/dpa
Pan Am lives on in Berlin
In 2019, no new 747s were ordered at all, though seven were still delivered. In all, over 1,550 have been made in the past five decades. Nonetheless, the heyday of the second jet age and Pan Am's double-deck glamour days is still alive at the Pan Am Lounge in Berlin. Still decorated in its classic 1970s style, today it's a private club full of nostalgia and can be rented out as a party location.
Image: Imago Images/APP-Photo
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The FAA said an inspection discovered the crack in the skin of the plane's crown but that it was too early to say whether the frequency of inspections should be increased.
Airlines are required to inspect the skin of a plane's crown behind the cockpit every 1,500 flights.
'Inspections met rules'
Southwest spokeswoman Michelle Agnew said the aircraft had been inspected for any cracks within the required 1,500-flight period.
She said the pilots had "followed standard procedures by descending to a lower altitude to maintain a safe and comfortable cabin environment" and that the move "resolved the issue."
Agnew added that the jet was now in a maintenance facility undergoing repairs of the crack.
A Boeing spokesperson said the manufacturer was aware of the incident and was collaborating with Southwest to learn more, the Associated Press reported.
The Dallas-based low-cost carrier has faced increased scrutiny following several incidences where it has failed obligatory inspections for fatigue cracks on some of its planes. Just last month, the Transportation Department's inspector general said the airline flew jets it bought without having first verified their maintenance and repair histories.
"Many officials throughout the FAA have expressed concern about the safety culture at Southwest Airlines," the department said. The airline has denied the allegations.
Cracks in other jets
The Wall Street Journal, citing people familiar with the matter, said Southwest told the FAA that mandatory inspections had found external cracks in two other aircraft in the same area but that those cracks didn't result in cabin decompression.
Maintenance experts say cracks are usually caused by fatigue or wear and tear and are not uncommon in older planes.
Inspections are put in place to ensure they are repaired before they pose a threat to safety.
In 1988, an Aloha Airlines flight attendant was blown out through a hole of a Boeing 737 as it flew over the Pacific Ocean, prompting stricter regulations.