"I can't think of a better one," Bethune said Wednesday on CNBC's "Closing Bell."
On Tuesday, a fan blade came off the CFM56-7B engine on Southwest Airlines Flight 1380, which was traveling from New York to Dallas, shattering a window. The aircraft made an emergency landing in Philadelphia, where a passenger died — the first fatality from a U.S. commercial airline accident in almost a decade.
"This never happens," said Bethune, who served as chairman and CEO of Continental from 1994 to 2004. "And the likelihood of it happening again in your lifetime is probably remote."
Still, the incident prompted experts to look for systemic issues with the widely used CFM56, including signs of fatigue in fan blades. The same engine was linked to a 2016 event.
In response to Tuesday's tragedy, Southwest Airlines said it is accelerating engine inspections. United Airlines said it will do the same. In addition, Delta Air Lines said it would comply with any changes instituted by regulators.
The engine powers some 6,700 aircraft around the world, according to its manufacturer, CFM International, a joint venture of General Electric and France's Safran Aircraft Engines. The engines have been in circulation since 1997 and are widely used in Boeing 737-700 planes. On average, a plane takes off somewhere in the world with a CFM56 engine every two seconds.
But, former National Transportation Safety Board member John Goglia said there is no cause for alarm.
"The last [engine problem] was two years ago," he said Wednesday on "Power Lunch." "Do the math; that's a couple million flight hours ago," said Goglia, who has more than four decades of experience in the aviation industry.
Goglia, who writes for the online publication Aviation International News, said engine failure of modern engines is rare.
"The engines today are unbelievably reliable," he said. "They're built with the best materials."
"I'm not the least bit concerned about getting on an airplane with a CFM engine on it," he added. "I fly on them every day."
More anxiety-inducing than engine issues, Bethune said, were passengers misusing oxygen masks during an emergency. He said he was "flabbergasted" to see photos of passengers circulating online with the masks only covering their mouths, especially "when the flight attendant says to put the oxygen mask over your nose and mouth every time they leave."
Bethune added that passengers have become "complacent" about airline safety because fatalities in the U.S. are so rare.
Shares of General Electric went unscathed on Wednesday. Meanwhile, stocks of Southwest rose slightly, from $55.81 to $55.82.