A few days ago I found myself in a situation where I was considering leaving the aircraft after reaching my seat. You see, I am a tall person (6'4") and I usually fit seats in economy just ok (meaning they are not comfortable but I can manage a few hours).

However this time I tried an airline that I had never used before and after sitting on my seat I found the seat pitch and the seat design together so bad that it was actually painful right from the start. On top of that staff forced me to take my hand luggage under the seat in front of me leaving me in an extremely difficult situation with zero ability to move my feet. Of course this was something I didn't expect - otherwise I had never booked this airline or at least I would have tried to secure an exit row seat when booking or checking in.

I decided to stay on board and that became the longest and most painful 5 hours on board ever. I then started to think what is the procedure if a passenger decides to disembark during the boarding? Any consequences for the passenger? For security reasons the airline would most likely load checked bags off and that would possibly delay the flight. Could they apply any fees for the passenger? If one would be concerned about his/her health would that be a good enough reason to leave the aircraft?

I'm usually flying in Europe and Asia if that matters.. Any insights welcome though.

I have disembarked after boarding. I forgot something at the chair I was sitting at in the boarding area. I told the GA why I leaving the aircraft and that I would return. I can not remember what they did. I left my personal items on board and had no checked luggage.

If a PAX leaves the flight completely, checked bags will be off loaded and one will be removed from the manifest. The ticket would also be canceled as if one never showed up at all.

If you want to disembark, then you disembark.

What happens will depend on the carrier, the country, and sometimes the specific airport.

So, without your specific situation, it is impossible to explain what would likely have happened to you on your carrier on your flight.

This one was TAP Portugal from Lisbon (LIS) to Stockholm (ARN).

Actually they have the information on their website saying the pitch in economy class (A320) is only 28". Had I checked that information I wouldn't have booked TAP since there were options for about same price. I kind of went into a trap thinking TAP is probably not an LCC but oh well.. they all become LCCs nowadays. Depending on seat design I can manage on 29" pitch but I think this was the first time I ever came across with 28" pitch. That seems to be my definite limit.