I learn how to pack a bike so It won't be very easily damaged..
last Trip I checked into SFO,with a 2nd hand Amtrak Box,
the Aircarrier wanted to sniff my empty MSR stove bottle and so forth,
and as a result gave me a fresh Box...

I have returned Via AMS and bought a box from KLM for about 20 Guilders
yup, PreEuro..

key, lots of packing tape and Zip tie things to the frame so If the carton Holes ,
nothing will fall out.

Roll up tubes of cardboard for cross braces.. and if you remove the wheels put a block
in the dropouts so there is not going to be a crushing of the dropouts.