That is, of course, exactly it. Sherlock grimaces a little, hating for his vulnerabilities to be laid so bare. But this is Ted. He's come to trust the man, to care for him. He knows that trust and care is mutual. And one of the things he's learned from Watson is that vulnerability within trust and care is not only safe, it strengthens the bond.

"The captain," he says, quietly enough that only Ted can hear him. "He was listing to one side as he walked on the plane. A bad ankle? A drink too many at the airport bar? A cerebral ischemia that has yet to make itself known?" He nods toward a man two rows ahead of them. "That man has served time for a violent crime, and he has been eyeing the flight attendants. Does he want a drink" A date? Or is he deciding which attendant to take hostage?" He lifts a finger, listening to the idling engine. "There is a slight knocking in the left wing engine. It could be an irregularity that is only noticeable when the engine is idling, or it could be a missed fracture in the gusset that will cause a mid-flight disintegration."