Anyone who has flown on a commercial airline recently will know that airplanes seem to be getting more crowded as airlines shrink seats and aisle space to fit in more passengers.

But do those cramped conditions pose a safety risk? Some experts say that it does.

“The statistics are pretty clear that most fatalities occur not because of impact on crash landings but because people cannot get out quickly enough,” says Paul Hudson with the nonprofit group Flyers Rights, a group that is calling on the government to regulate the size of airline seats.

“There’s a rule called the 90-second rule that says everyone has to be able to get out in that amount of time. There’s a big question whether that’s possible with shrinking seats and larger passengers,” Hudson says.

The Federal Aviation Administration appears to be taking notice. The agency will run tests next month to see if passengers can evacuate an airplane fast enough to meet the safety standards.

The study will simulate a real plane crash and the crew will have 90 seconds to get everyone off. But each time, half of the exits will be locked and the crew will not know which ones those are. The passengers will be volunteers of all ages, including children, senior citizens and possibly those with service animals.

But Flyers Rights says that it isn’t convinced that the FAA will take the testing seriously.

“Although I’m on the committee that’s studying the evacuation, I just found out about it and the details have been kept secret,” says Hudson.

Hudson’s group is also calling on the FAA to release the full test results and not just a summary.