Alaska Airlines says it has returned some of its grounded Boeing 737 Max 9 jets to service after one of its planes lost a section of fuselage mid-flight.
The airline apologised to those affected, saying an inspection found “no concerning findings”.
On Friday one of its planes had to make an emergency landing in the US state of Oregon after an outer section of the plane fell off.
The plane, carrying 177 passengers and crew, landed safely in Portland.
Boeing said it was aware of the incident and was “working to gather more information”.
The UK Civil Aviation Authority told the BBC it was “monitoring the situation very closely”.
Evan Smith, one of the 171 passengers on board, said: “There was a really loud bang towards the left rear of the plane and a woosh noise – and all the air masks dropped.
“They said there was a kid in that row who had his shirt was sucked off him and out of the plane and his mother was holding onto him to make sure he didn’t go with it.”
Diego Murillo said the gap was “as wide as a refrigerator”.
Fellow passenger Elizabeth Lee added: “Part of the plane was missing and the wind was just extremely loud. but everyone was in their seats and had their belt on.”
Jessica Montoia described the flight as a “trip from hell” adding a phone was taken out of a man’s hand by the wind.
Announcing the initial grounding of 65 planes, Alaska Airlines’ CEO Ben Minicucci said: “Each aircraft will be returned to service only after completion of full maintenance and safety inspections.”
A later statement said that more than a quarter of those plans had been inspected and would return to service as there were no issues found.
The flight to Ontario, California, had reached 16,000ft (4,876m) when it began its emergency descent, according to flight tracking data.
Images sent to news outlets show the night sky visible through the gap in the fuselage, with insulation material and other debris also seen.
Other pictures show the seat closest to the affected section, a window seat that passengers said was unoccupied, leaning forward without its cushion.
“My heart goes out to those who were on this flight – I am so sorry for what you experienced,” Mr Minicucci said. “I am so grateful for the response of our pilots and flight attendants.”
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