The United Airlines Boeing 737-800, carrying 139 passengers and six crew members, landed in Oregon on Friday without its external panel.

The airline had taken off from San Francisco. It landed safely at the Rogue Valley International Airport in Medford, Oregon, at about 11:30 (18:30 GMT) on Friday with its panel missing, according to the airline and the U.S. Federal Aviation Administration.

A senior official at Rogue Valley International Medford Airport, Amber Judd, confirmed that the plane had landed safely without its external panel, adding that the panel was only discovered missing during a post-flight inspection.

Ms Judd said, “We’ll conduct a thorough examination of the plane and perform all the needed repairs before it returns to service,” while assuring that an investigation would be carried out “to better understand how this damage occurred.”

The missing panel also attracted the attention of the FAA, which stated that it is investigating how the panel came apart.

According to images posted on social media by the Rogue Valley Times, the missing panel was seen next to the plane’s landing gear as all outgoing and incoming flights were paused at the airport to search for it.

Meanwhile, Boeing has been under heavy regulatory scrutiny after the January 5 incident in which an Alaska Airlines Boeing 737 Max 9 door plug blew off a few minutes after take-off, leaving a gaping hole in the side of the plane.

Following the incident, Mike Whitaker, the head of the FAA, told lawmakers on January 7 that inspections of the 737 Max aircraft revealed that “the quality system issues at Boeing were unacceptable and require further scrutiny.”

He stated that, based on the investigations carried out, four key bolts meant to lock the unused door to the fuselage were found to be missing and added that Boeing would be held accountable for any future failure or refusal to comply with the FAA.

Also, a Boeing 787-9 Dreamliner flying from Australia to New Zealand had left around 50 people injured after it had suddenly landed without warning, causing passengers who did not have their seatbelts to tumble from their seats to aisles and into the ceiling.

Meanwhile, despite the various incidents, experts and regulators say that commercial aviation is still one of the safest travel methods.