Boeing has been in the headlines a lot lately following a series of incidents after the January Alaska Airlines near-miss in which a door panel came off mid-flight.
The episodes point to production and maintenance issues, say experts, who don't see an obvious pattern behind the myriad incidents.
The US plane maker has been under scrutiny since January 5, when a Boeing 737 MAX 9 operated by Alaska Airlines made an emergency landing after a fuselage panel blew out, successfully resolving an incident that safety officials say could have been catastrophic.
United Airlines in particular has experienced recent issues, including cases where a plane lost a wheel shortly after takeoff, another that rolled onto the grass during taxiing and a third that returned to its departing airport following an engine fire.
Over the last week Southwest Airlines had two separate incidents involving Boeing planes, including an engine fire.
Such a confluence of incidents is "pretty rare" within air travel, said aviation expert Bertrand Vilmer, who said the myriad "abnormal" problems reflect "an alignment of unfavorable planets."
Aviation experts usually look to three possible explanations for problems.
There can be a design defect, as with the two fatal crashes on 737 MAX jets in 2018 in Indonesia and 2019 in Ethiopia that involved a flaw in a flight stabilizing system.
Aviation watchers have pointed to a production defect as the likely source of the Alaska Airlines incident, which entailed a Boeing 737 MAX 9 that had only been delivered in October.
A preliminary report by the National Transportation Safety Board published in February found that four bolts meant to help secure the panel that blew off were missing.
A third possible cause would be insufficient maintenance.
While design and production are the responsibility of the plane maker, the airline is in charge of keeping up the plane once it receives it.
"Once the aircraft is delivered, Boeing has nothing to do with it anymore" in relation to maintenance, said Richard Aboulafia of AeroDynamic Advisory, adding that "there is a maintenance issue all over the world."
Vilmer notes that airplane maintenance is under the purview of the US regulator, the Federal Aviation Administration.
Notwithstanding the recent spate of incidents, aviation experts point to a strong safety record overall.
"We haven't had a single casualty in the entire US airline industry, in way over a decade, despite millions of people flown," said Aboulafia. "That's incredible."
Aboulafia calls modern flying "the safest form of transport ever created by people," noting that "everyday, hundreds of people get killed on the roads."
Boeing's rival, Airbus, has not been completely spared of difficulty. Hundreds of planes produced by the European company are being taken out of service to check for microscopic "contamination" of metals in engines made by Pratt & Whitney.
Airbus also had a public dispute with Qatar Airways involving the degradation of exterior plane surfaces.
But there have been fewer such issues at Airbus and not one incident that drew a comparable level of attention as Alaska Airlines, experts said.
"Every incident that has occurred on Boeing airplanes this year has made headlines, suggesting that Boeing airplanes are unsafe," said a note last month from equity research firm Bernstein.
"The reality is that the number of incidents in the US on Airbus and Boeing airplanes so far this year is proportional to the number of airplanes in the fleets of US carriers."
The US commercial fleet currently has about 4,800 planes, with about 60 percent Boeing planes, according to Cirium, an aviation analytics firm.
