Ted smiles with amusement at that being Sherlock's main concern. He supposes it's comforting, to know one in their party is always considering how to deal with potential problems. Ted does too, he supposes, they just have wildly different priorities. Ted considers whether they'd get hungry or bored, while Sherlock considers emergency landings. Between the two of them and Joan's medical expertise, they should be pretty covered for most eventualities.

"Why's their numbering convention like that?" he asks. "787, 747, all that."

Ted's always curious to learn things, but mostly he's asking to let Sherlock cover the talking for a bit, and with Ted asking questions, they should be comfortably able to fill the silence till they get to the airport, and Joan can engage as much or as little as she wants.