Sex For Charity Isn’t Prostitution, Right?

When does selling ones self for sex count as prostitution? If that person is selling themselves for a good cause does that change things? I guess that all depends on your point of view and who you ask.

Catarina Migliorini, a 20 year old Brazilian student, has put her virginity up for auction for charities building houses in her home country.

Migliorini has this to say to the people who say what she is doing is prostitition,  "If you only do it once in your life then you are not a prostitute, just like if you take one amazing photograph it does not automatically make you a photographer... Makes sense to me, I guess...

So far the highest bid is $155,000.00 , once the auction ends, the encounter will be featured on Australian TV, and just to keep it legal will take place on an airplane... My question, if it's not prostitution if you only do it once, why does it have to take place in an airplane to avoid "illegalities."