I don't understand what the problem is. The job advert said the interviews will take place between certain dates, and they're taking place between those dates. If you can't do those dates, why bother applying?
TUI do assessments over a week, they pull a specific set of pilots off the line to conduct them with the HR department. They're not going to add extra dates just for you, they have over 900 applicants for less than 50 jobs.