A plane loaded with Edmontonians bound for Puerto Vallarta was forced to make an emergency medical landing in Montana Sunday morning after a flight attendant was injured when the aircraft hit turbulence.

Sunwing's Flight 559 was carrying 181 passengers and 6 crew members when it hit a patch of “extreme turbulence” defined as 90 seconds of sustained turbulence mid-air over Montana.

“The aircraft experienced extreme turbulence and two of our flight attendants [who] were in the aisle at the time were flown up into the air and landed in the aisle,” said Janine Chapman, the airline’s vice president of marketing.

“The one flight attendant got a small lesion on his head upon landing and so we radioed for medical assistance as a precaution and took the decision to make a landing in Helena.”

Chapman said all passengers were already in their seats with the seat belt sign on when the turbulence struck. No passengers were injured.

Unexpected layover in Helena

Upon landing, passengers had to wait on board the plane until they could be cleared by customs officials.

“Unfortunately, Helena is a small airport that doesn’t have customs working on weekends so unfortunately our customers did have to stay on the plane for a period of time before we could get any customs agents in to clear them so that they could go into the airport,” Chapman said.

While they waited, passengers were given a meal service, she added.

Both flight attendants were examined and cleared by medical officials.

The plane itself is also being checked for damage, which Chapman said is customary following an incident if extreme turbulence.

“We are sending a new aircraft to come pick them up with a new crew. That aircraft is scheduled to depart at 5:30 p.m. local time from Helena so they will be arriving this evening into Puerto Vallarta at 9:20 p.m. local time there.”

Chapman reported that passengers – most of whom were families on their way to vacation – were in relatively good spirits despite the scare and unexpected stop.