From labyrinthine security checkpoints to cramped seats and scant overhead storage space, air travel ranks among the most grueling experiences out there (unless you’re one of the rarefied few who spring for first class). With its A350 XWB jet, Airbus integrates the latest design and engineering tricks to quell many of the headaches for flyers, carriers, and pilots. Chief among them? Jet lag. “The design process was about optimization, pushing the constraints, and opening up…