The Southwest flight had just taken off from Burbank in California when the pilot received an alert about a nearby plane.
Data from FlightAware shows the aircraft dropped by 91m (300ft) in just 36 seconds. Those on board said they felt panicked, and some feared the plane was about to crash.
Comedian Jimmy Dore posted on X: “Pilot had to dive aggressively to avoid mid-air collision … myself and plenty of people flew out of their seats and bumped heads on ceiling, a flight attendant needed medical attention.”
Stef Zambrano saw a woman who wasn’t wearing her seatbelt thrown out of her seat, who then said: “I want to get off this plane. I want to be on the ground.”
Another passenger, Steve Ulasewicz, told NBC Los Angeles that it felt like the plane was in freefall for 10 seconds.
“People were screaming. You know, it was pandemonium. People thought the plane was going down,” he added.
The aircraft was able to continue to its destination of Las Vegas, where it safely landed without any further incident.
It is believed the Boeing 737 was in the same vicinity as a Hawker Hunter Mk. 58, a British fighter jet.
Southwest is now working with the Federal Aviation Administration “to further understand the circumstances” of the event.
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This is the second time in a week that a passenger plane has had to make abrupt flight manoeuvres to avoid a potential mid-air collision.
Concerns have been raised about aviation safety in the US following a series of recent incidents.
In January, a mid-air collision in Washington DC killed 67 people.
