Air Force One’s aborted flight to Davos last week was one more stage in a prolonged failure to modernize the large jets that serve American presidents. The current airplanes have been in use for 36 years and are increasingly hard to maintain. Their aging has accelerated as President Trump makes frequent weekend trips to Palm Beach. More crucially, the program to replace them has for a long time become ensnared in the downward spiral of Boeing. Nobody has been more aware of Boeing’s shortcomings than Trump. A month before he began his first term as president, in December 2016, he summoned Dennis Muilenburg, the former CEO of Boeing, to Mar-a-Lago to be grilled on the costs of the Air Force One program, having threatened to cancel it in a tweet. After the meeting, Muilenburg praised Trump’s “business headset” and said he had agreed to cap the program’s costs at $4 billion. After another meeting with Trump in January 2017, Muilenburg said Boeing would “streamline the process” and achieve “substantial cost reduction.” Muilenburg’s objectives were never …