U.S. Del. Eleanor Holmes Norton (D-DC) in 2009. (Photo by Alex Wong/Getty Images)

Del. Eleanor Holmes Norton will introduce a bill to require the Federal Aviation Administration to keep statistics on sexual assaults that occur on airplanes.

The bill comes after NBC4 reported on four such assaults in February.

FBI agents have investigated at least four reports of sexual assaults aboard airplanes en route to Reagan National and Dulles International airports in recent months. In two cases, the attackers were charged with federal crimes, the News4 I-Team has learned.

And although federal law enforcement officers admit onboard sex assaults are often complicated to investigate, the News4 I-Team’s review found no federal agency is maintaining data or statistics showing the frequency of sex assaults on airplanes. The major airlines were unwilling to publicly disclose any of their own tabulations on attacks.

Norton’s bill “will include domestic and international flights that land in or depart from the U.S.,” according to a release. “The data would be made accessible to the public through the FAA’s website.”

“Without some real-time statistics and documentation, we cannot gain either the necessary information to prosecute these crimes or the insights to help eliminate them and improve complicated onboard sexual assault investigations by the FBI,” Norton said in a release. “Airplane passengers expect that after going through extensive security that they will be safe aboard their flights, but recent surges in reports of sexual assaults occurring on planes say otherwise. Those who staff flights and who may witness these crimes should have guidance as to how to proceed. Law enforcement and the flying public deserve to have access to data on sexual assaults that occur aboard planes so that we can work towards preventing these devastating crimes.”