A husband and wife finds themselves in an elongated pocket of alternate time where their younger daughter is about to be killed by a truck.
When a test pilot crashes in his experimental X-15 plane, he and his wife discover they are in a reality where time has slowed down almost to a standstill. Returning to the airbase, they are horrified to see their daughter standing in the path of a moving truck and they seem to be unable to prevent her death.—gazhack