Two women are suing Frontier Airlines, saying that the company and its employees did nothing to prevent or respond to incidents of sexual assault on flights.

In the class-action suit filed in federal court in Colorado on Dec. 16, Lena Ramsay and an unidentified woman allege they were sexually assaulted on separate flights in 2018. The suit was filed on behalf of the two alleged victims and all passengers who have flown Frontier since Dec. 16, 2017.

"Frontier can — and has a duty to — implement and enforce policies and procedures to prevent and deter in-flight sexual assaults and to properly respond to those that do occur, just as it does with other forms of passenger violence and disruption," the suit says.

Ramsay was assaulted by a male passenger during an October flight from Denver to Providence, Rhode Island, according to the suit. She immediately reported what had happened to a flight attendant, but the flight attendant would not allow her to change seats, and then failed to report the incident to anyone, including law enforcement, the suit claims.

When Ramsay reported the incident to Frontier, the budget airline did not cooperate in providing her with evidence, including the identities of the man who assaulted her or of any possible witnesses, the suit says.

The second victim had a similar experience on a flight from Denver to Florida in November 2018, the suit alleges.

The FBI in 2018 issued a warning to airlines and air travelers that the number of reports of sexual assaults on flights were increasing "at an alarming rate," the suit notes.

"Frontier knew — or should have known — of this growing prevalence of in-flight sexual assaults because it is widely available and known public knowledge," the suit said.

But when the alleged victims and their lawyers asked Frontier to share its policies and procedures for preventing sexual assaults on flights, they never heard back, according to the suit.

Future customers of Frontier are at risk, the suit claims.

The suit seeks compensatory relief for the defendants and for any others who were "harmed by Frontier's common course of misconduct."

The suit also demands that Frontier implement policies that will deter sexual harassment and conduct training so that its staff knows how to respond to incidents of sexual harassment or assault on its flights.

A Frontier spokeswoman said she could not comment on pending litigation, but that "the safety of our passengers and crew members is our No. 1 priority at Frontier Airlines and we have strict policies in place to proactively and appropriately respond to reports of misconduct and alleged crimes."

The FBI, which has jurisdiction over offenses that happen in the air, stated in a 2018 release, "Flight attendants and captains represent authority on the plane … they can alert law enforcement, and they can sometimes deal with the problem in the air."

"The flight crew can also put the offender on notice, which might prevent further problems. If alerted in advance ... FBI agents can be on hand when the plane lands to conduct interviews and take subjects into custody. FBI victim specialists can respond as well, because victims of federal crimes are entitled by law to a variety of services," the agency said.