Air shipping for guitars is dangerous, because temperature and humidity regimes can be extreme, and flight loading (it can happen several times) can be very brutal (post delivery the same)... Ask sender to release strings some 2 semitones before shipping, and to put long piece of soft material between strings and frets/fretboard/pickups. Next level what can be done is removing knobs, pot nuts/washers, switch nut/screws and packing them separately, if possible - screw pickups deeper - shortly - deepening all possible what can be damaged. Guitar's body must be centred and stabilised into case from all sides. But never put something into headstock department of case, headstock and neck's upper part must be free!
Bolt-on guitar necks can be dismantled. Use double carton box without information about guitar inside - good working old anti theft method. But mark box as "Fragile!" + Glass symbol, and "Insured", mark "Top-Up^" side, add Umbrella symbol, do it from all sides. All it together will as minimum double safety for this shipping "lottery"...