Disassemble the handlebar, place it in the longitudinal direction and fix it to the frame with self-adhesive tape and the wheels so that they do not turn anymore.
Remove the pedals with a wrench. Be careful that the left pedal is removed by turning the key clockwise (as shown in the picture) while the right pedal is the opposite.
Place the pedals inside by screwing them.
Deflate the tires and place the wheels well longitudinal.
Then there are two methods of packing.
The first is the use of a cardboard box that you can find at a bike dealer.
Place the bike in this box.
And close it.
To transport the carton to the airport, fold it and place it on your back support by securing it strongly.
The second method requires stretch wrap and pieces of card board that you place on the front wheel and rear wheel to protect the entire derailleur.