URBANA, Ill. (WCIA) — An American Airlines plane hit a U.S. Army Blackhawk helicopter near Washington, D.C., killing 67 people. The deadliest U.S. air crash since 2009.

Investigators haven’t stopped working since last night, going through the wreckage for answers. One University of Illinois professor has some insight into what could happen in the future.

Aerospace engineering professor Phil Ansell teaches flight mechanics and sustainable aviation, meaning protecting people from what flying can bring. He was deeply saddened by the accident, and talked about how unusual it was.

The plane took off from Wichita, Kansas and flew toward Ronald Reagan Washington National Airport. At the same time, a Blackhawk helicopter was doing a drill over the Potomac River, and they collided.

There were 60 passengers and four crew members on the plane, and three soldiers on the helicopter. Everyone died. Ansell said both commercial airlines and the military may change some of their flight rules after this crash.

“You kind of take a look at the situation and try to say, well, what does this mean for us? What’s next for how we operate aircraft?” Ansell said. “Part of sustainability is really ensuring that not only can we deliver aviation in an environmentally responsible way, but ones that ways that actually promote human health, well-being. We want people to live their best lives with using aviation as a service.”

Ansell said the number of planes flying around the Washington D.C. metro area can be a logistical nightmare, keeping up with all the planes going in and out of a small area.

He also said this situation is unique because of the military aspect. There have been scares with unmanned aircrafts in the past, but he considers this an unprecedented event that could change how aviation works across the country.