It is important to wear comfortable clothes, that's for sure!
As an (Incharge) F/A I look at all things from the standpoint of safety.
I would advise natural fibres as they provide a higher level of protection as opposed to synthetic fibres which in a fire will melt onto your skin. That's why our uniforms are 100% Virgin Wool as required by International Aviation Regulation.
Long pants and long sleeves will provide more protection in an Emergency as well.
Ever notice that just prior to critical phase of flight, Crew always have their longsleeved blazers on? It's actually a regulation we must follow so that we are more protected in case of an emergency.
Dress in removable layers. You'll appreciate a l/s removable over jacket even if it's a warm day outside. The back of the A/c can be chilly. Sports bras are also a good idea for comfort.
Shoes should be well broken in. Ideally lace up so they can be tightened and loosened. No flip flops or high heels.
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