The drill is familiar for most airline passengers: how to buckle up your seat belt, put on the oxygen masks and use the seat cushion as a flotation device. What flight crews don’t tell you is what to do if you suddenly find yourself in an upside-down aircraft.

For the passengers of a Delta flight on Monday, that became an extremely crucial detail.

Expert engineering, the size of the aircraft and seatbelts all probably played a role in protecting people aboard a passenger jet that flipped over at an airport in Toronto, experts said Monday, the latest in a string of high-profile crashes that have raised questions about aviation safety.

The plane, a Bombardier CRJ900, flipped upon landing at Toronto Pearson International Airport. All 80 people aboard were evacuated, according to Delta. Eighteen injuries were reported, most of them minor to moderate.

More: Investigation into why Delta plane flipped on its roof is underway

Though it is extremely rare for an aircraft to flip on its back, planes are engineered to handle it, said Mike McCormick, associate professor and program coordinator for air traffic management at Embry-Riddle Aeronautical University in Daytona Beach, Florida.

The structural elements of an aircraft are designed so that the wings and the tail will break off and away if the plane tips over, McCormick said. The seats are designed to withstand impacts up to 16 times the force of gravity, so they will remain in place when the plane is upside down.

That’s why people are asked to be strapped in at takeoff and landing, he said. “Absent any loose things flying around the cabin, the seats are designed to keep the passengers strapped in.”

Scenes showing the cabin crew swiftly directing passengers out of the aircraft are a testament to their training, McCormick said.

“Most people think of them as flight attendants serving refreshments and answering questions. Where they really perform their true function is during experiences like this when their experience and training comes into play.”

Despite the high-profile crashes this year, “we are in the safest time in aviation history,” McCormick said.

Travel safely: Sign up for USA TODAY’s Travel newsletter for best trip tips.

Small size of plane cushioned fall

Arnold Barnett, a leading aviation safety expert and statistics professor at the Massachusetts Institute of Technology, told USA TODAY he was surprised to see the plane flip over, noting the crash could add to flight anxiety after recent crashes near Washington, D.C., in Alaska and in Philadelphia.

Barnett said the plane going belly-up was akin to a “horrible rollercoaster,” but the plane’s size and passengers’ use of seat belts likely helped minimize injuries.

“It’s the kind of thing that can be, to say the least, unnerving,” he said, but would not necessarily cause serious injuries.

The CRJ900 jet’s cabin height is roughly 6 feet, which meant people didn’t have far to fall when it overturned, Barnett said.

Fire danger spurs speedy evacuations

Najm Meshkati, professor of engineering and expert of aviation safety at the University of Southern California, said the biggest concern in any plane crash is the risk of fire. He cited a disaster in South Korea in December that killed 179 people when a commercial plane veered off the runway, slammed into a wall and burst into flames.

Meshkati noted the flight crew acts as another layer of fire protection for passengers by ensuring a quick and orderly exit, which may have saved lives.

Hassan Shahidi, president and CEO of the Flight Safety Foundation, lauded the airport’s first responders.

“They were there immediately dousing the aircraft with fire-resistant foam,” he said. “The Toronto Airport is known for being on top of these emergency-type situations.”

Their training was also “very visible” Monday as emergency crews arrived moments after the crash, he said.

“All these things are very important in today’s accident that passengers were able to walk out of that airplane without any fatalities.”

Shahidi also lauded the actions of the cabin crew “under very difficult circumstances” that they were able to help passengers reach the exit doors and ensure they were operable. He noted crew members go through rigorous training for emergency evacuations, including in unusual circumstances such as a flipped aircraft.

From a design perspective, the aircraft are engineered to withstand all sorts of pressures.

“They are put through extreme stress tests to look at all sorts of different scenarios to ensure they’re safe,” Shahidi said.

It’s remarkable the passengers were well enough to stand and walk out of the plane, Shahidi said.

“We’re thankful and grateful that there were no fatalities and people were actually walking out.”

What can airline passengers learn from this crash?

Mike Shertz has been thinking about how to get out of an upside-down plane since reading about an Azerbaijan Airlines passenger jet that crashed during an emergency landing in Kazakhstan after it was struck by Russian air defenses in December.

In that tragedy, a large section of the aircraft appeared to break off and flip. Reuters reported 38 people died in the crash and 29 survived with injuries.

Shertz, an emergency room physician in Oregon, operates Crisis Medicine, a training program for emergency management of trauma patients in high-risk environments. He said the No. 1 thing to remember when flying is to fasten your seat belt and make it snug.

If the plane stops suddenly, “you’re going to be shifted forward in your seat, and a couple of inches could make the difference between you hitting something in front of you,” he said.

A passenger who suddenly finds themselves upside down in an airplane would be in a similar situation as someone inside a flipped car.

“It’s going to be massively disorienting,” Shertz said. “People don’t spend a lot of time hanging upside down.”

Before you release your seat belt, think about where you’re going to fall, he said, noting the ceiling that is now the floor is likely to be littered with debris.

“If you’re by the window you’re going to fall into the overhead,” he said, “and if you’re along the aisle you’re going to fall farther.”

Contributing: Zach Wichter, Nathan Diller and Thao Nguyen