(CNN) — More than two dozen officials with the National Transportation and Safety Board traveled Wednesday to the mangled remnants of a UPS cargo plane that crashed after an engine detached during takeoff near Louisville Muhammad Ali International Airport.

They’ll try to determine what led to the disaster that killed at least 12 people while destroying nearby businesses and buildings.

The NTSB will release a preliminary report within 30 days, but it could be 18 to 24 months before the investigation concludes, according to Jim Brauchle, an aviation attorney with law firm Motley Rice and former US Air Force navigator.

In the wake of Tuesday’s tragedy, family members of the crash victims will be waiting for the answers investigators are working to uncover, Brauchle told CNN.

“The one thing that all these family members, based on my experience, want to know is: How this could have happened?” Brauchle said. “It’s not something that happens every day, but I see it a lot. It’s more than grief.”

Here are some of the factors aviation experts say will be key to the investigation.

The crash left a half-mile-long debris field, and the first priority is dealing with rescue and recovery, said Mary Schiavo, CNN aviation analyst and former Department of Transportation inspector general.

The debris field is large, though certainly not the largest the NTSB or similar agencies in other nations have encountered, she said.

“Crash investigators have scoured miles of Scottish countryside (PanAm flight 103), miles of ocean floor (TWA flight 800), and the southern Indian Ocean (Malaysia Airlines flight 370),” she said, referencing previous plane crashes. “They carefully map where pieces are recovered. There are great software programs that help you do this as you work a debris field.”

Kentucky Gov. Andy Beshear, who ordered flags lowered to half-staff Wednesday in honor of the crash victims, urged residents to stay away from the site for their own safety.