E.T.A. is about a professional contract killer, who works as a flight attendant, enabling her to travel the world performing political assassinations.

I don't find the premise of a flight attendant working as a professional killer to be credible.? Because if he's any good,? he would earn more than enough money to cover travel expenses. Or have no problem billing travel expenses to the client.

More importantly, working as a flight attendant ties him to the airline work schedule of where and when he can go; he doesn't have the flexibility he needs to methodically plan and execute his jobs.

However, if he was a serial killer whose idea of recreation during layovers is to engage in random acts of murder and mayhem...

This is another logline that you have written from the point of view of a narrator instead of the lead character.

Agreed with Variable.

Is this a TV series or film?

I think this basic premise would make for a great TV series and you should seriously consider developing it for VOD streaming services.