A deadly midair collision in January between a military helicopter and a commercial airliner, and several crashes since, have prompted officials to focus on fixing the nation’s outdated air traffic control system and hiring more controllers.

According to a new report from CNN, air traffic controllers "repeatedly" warned of major safety issues and technology outages as early as last summer, months before the April 28 outage that has been a major factor in the widespread delays and cancellations at the second-busiest airport in the New York City area.