Passengers have recounted the "terrifying" moment when a Ryanair flight was forced to make a rapid emergency descent over the Swiss Alps after a pressurisation warning. Those on the flight from Milan to East Midlands airport on Wednesday heard a bang, before the oxygen masks fell, and felt the plane descending rapidly for thousands of feet as their pilot called "mayday".

Melvin Frater, 55, from Nottingham, who was returning from holiday with his wife Jacqueline, could see snow-capped mountains "coming up fast" as the Boeing 737 with 134 passengers made its emergency descent.

"We were approximately 20 minutes into the flight when we felt and heard a bang, followed by very cold air, rushing by our feet, from the front to the back of the plane," he said.

Children and babies began crying as passengers followed safety procedures, he told the Press Association. Then a pilot's voice came over the intercom, saying "mayday, mayday".

Melvin Frater told the Times: "It was snowy below us. We came down about four miles in five minutes and the pressure on our ears was tremendous … we thought 'This is it.'"

"We were falling towards the earth and until [the pilot] actually levelled up, we were just thinking: 'It's our time.'"

According to Frater: "It was quite strange that, unlike the scenes of panic and screaming which accompany cinema portrayals of such situations, there was initially a real sense of calm and quiet ..."

Once the plane had levelled out, the captain apologised and told passengers the crew had followed correct procedures to cope with sudden loss of pressure and they had reduced altitude to 9,000ft.

Jacqueline Frater, who organised the trip for her husband after he was made redundant last year, told the BBC: "You could see the whites of the eyes of people next to you. People were panicking, but they weren't screaming or shouting. You heard the captain, 'mayday, Ryanair, mayday, mayday' and he was saying it rapidly as we were going down. I thought my number was up."

One person on the flight told the Aviation Herald website: "It was terrifying to see nothing but Alps all around. I didn't know how we were going to land." Another said "the cabin crew and everyone were excellent" while some passengers "began crossing themselves " and others removed shoes ready for an emergency landing, according to a third person. The plane was diverted to Frankfurt-Hahn airport where three people went to hospital for ear pain. Ten others had minor injuries but did not require hospital treatment. A replacement plane took passengers to England.

Ryanair said the flight diverted after the captain identified a pressurisation warning, deployed the oxygen masks, and descended to 10,000ft as recommended. "The aircraft landed … and passengers disembarked normally."