I don't know their situation, but in my imagination it goes something like this...
... they'd been in the car all evening. The boys were getting noisy and the parents were getting agitated. They'd decided to drive to Chicago to spend the weekend Christmas shopping, but now were regretted that decision. Mom had begged for the trip. She relented when the forecast called for snow, but Dad said "I'm not afraid of driving in a little snow."
The younger boys were in carseats, but Joshua just had a lap belt, which he frequently escaped. He was sitting on the floor between the seats when they stopped at the light at 55th and Central.
Mom had gone from asking to coaxing to yelling, trying to get Joshua to sit in his seat. Finally, Dad grabs Joshua by the shirt and lifts him onto the back seat and gives that threatening Dad look. "Don't Move a Muscle!"
Both look forward just long enough to see an unbelievable site, a 737 skidding into the intersection. It crushes their SUV like an aluminum can.
Regardless of the real situation, the freak nature of it, they will both blame themselves for little things.
The younger boys will forget their brother in time, but Christmas will never have the same flavor as it does for other children. The parents will have a sad memory guaranteed to be rekindled at the same time every year.
I read the story last night around midnight, just hours after it happened. That kicked off my dreams. I have frequent nightmares of losing one of my children. I can't imagine losing a child, but losing one near Christmas would be even worse.