The CEO of United Airlines says that a slew of recent incidents ranging from a panel that fell off a plane to another jet losing a wheel on takeoff will cause the airline to review its safety training for employees.

CEO Scott Kirby said the airline was already planning an extra day of training for pilots starting in May and changes in training curriculum for newly hired mechanics.

In a memo to customers on Monday, Kirby tried to reassure travelers that safety is the airline’s top priority.

“Unfortunately, in the past few weeks, our airline has experienced a number of incidents that are reminders of the importance of safety,” he said. “While they are all unrelated, I want you to know that these incidents have our attention and have sharpened our focus.”

Kirby said the airline is reviewing each recent incident and will use what it learns to “inform” safety training and procedures. He did not give any details beyond measures that he said were already being planned, such as the extra day of training for pilots.

Some of the recent incidents might not normally attract much attention but have gained more news coverage and clicks on social media because of their sheer number affecting one airline in a short period of time. Also, there is heightened concern about air safety since a panel blew off an Alaska Airlines Boeing 737 Max at 16,000 feet above Oregon; investigators say bolts securing the panel were missing.

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In the most recent incident, a chunk of fuselage skin fell off the belly of a United jet on Friday. The Boeing 737-800 was built in 1998.

Also last week, a United flight from Dallas to San Francisco suffered a hydraulic leak, and another flight bound for San Francisco returned to Australia two hours after takeoff because of an undescribed “maintenance issue.”

Earlier this month, a United flight returned to Houston after an engine caught fire, and a tire fell off a United Boeing 777 during takeoff in San Francisco.

United planes have even had mishaps while on the ground. On March 8, a jet landing in Houston rolled off an airport taxiway in Houston and got stuck in grass. Workers had to haul out moveable stairs to help passengers exit the plane.

There were no injuries in any of the incidents, some of which are under investigation by federal officials.