For men, tailored pants, a collared shirt and perhaps a pullover are likely to do. Not too casual, not too formal and layered to cope with the change in temperature. Shoes are important. Many passengers have a preference for throwing them off and getting well acquainted with the airline-provided socks. Again, it cannot be stressed often enough go for comfort and a pair of shoes that will accommodate a slightly expanded foot.
Women stay away from heels.
Anyone who tried to indoctrinate you into thinking that heels equalled elegance was obviously lying. There is nothing remotely chic about backache, or tripping as you try to manoeuvre your hand luggage up the plane stairs besides, if God forbid you have to use the airplane slide, you will be compelled to leave the Blahniks behind. So you are now settled in your seat, comfortably dressed, ready for your plane trip. Some extra precautions are needed to avoid, as much as possible, looking like you just got off a long haul flight when you get to your destination. Alternatively, spritz your face on occasion with an energising, refreshing spray.