Adelina Lancianese

Southern West Virginia is a playground for hikers, cyclists and rock climbers, but in the heart of that lush landscape rests the site of what many consider the worst industrial disaster in American history.

Today, from a picturesque overlook on the mountain above, tourists can see the gate of the Hawks Nest Tunnel, located on the New River in Gauley Bridge. There, water rushes through 16,240 feet of steel and rock.

Retired Army Sgt. Kevin Crowell boarded an American Airlines flight from Miami to Key West with his wife and his psychiatric service dog Bella in April 2014. They were heading to a couples retreat sponsored by the Wounded Warrior Project.

Crowell, who has been diagnosed with Post-Traumatic Stress Disorder from an explosion during his deployment to Iraq in 2004 and 2005, says he made sure he properly documented the golden retriever over the phone, days ahead of his trip.