11:20 AM EDT, 03/18/2024 (MT Newswires) -- The US Federal Aviation Administration plans to investigate three recent incidents involving Boeing ( BA ) 737 planes that were being flown domestically by United Airlines (UAL) and American Airlines ( AAL ) , according to the regulatory body's website.

On Friday, a post-landing inspection of a Boeing 737 operated by United Airlines revealed a missing panel. The flight landed safely at Medford Airport in Oregon after departing from San Francisco International Airport.

That same day, an American Airlines ( AAL ) flight that landed safely at Logan International Airport in Boston was reported by the crew to have "a flap issue," according to the FAA's website. The Boeing 737-800 plane departed from Dallas-Fort Worth International Airport in Texas.

On Sunday, a United Airlines flight was reported by the crew to have an issue with the air data indication. The Boeing 737-800 aircraft landed safely at Chicago O'Hare International Airport after departing from LaGuardia Airport in New York.

Shares of Boeing ( BA ) dropped 1.5% in Monday trade.

Boeing ( BA ) and American didn't respond to a request for comment. In a memo sent to customers on Monday, United Chief Executive Scott Kirby addressed some of the recent flight safety concerns and committed to safety.

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

The carrier is reviewing each case to understand what happened, with plans to improving safety training and procedures, according to Kirby. The company has already enacted an extra day of in-person training for all pilots that will begin in May and built a centralized training curriculum for new-hire maintenance technicians, he said.

The FAA's website showed that the crew on a United Airlines Airbus A320 flight on March 14 reported a possible hydraulic issue. The regulator will investigate the matter. Airbus didn't immediately respond to a request for comment.

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