Heathrow Airport is calling on 15,000 volunteers to help test out facilities at the new terminal five building.
Airport operator BAA said it wanted to ensure the terminal "runs like clockwork" when it opens in March.
A free lunch and goodie bag are on offer to those who take part in the six-and-a-half-hour dress rehearsals which begin for six months on Monday.
Construction workers handed control of the building to BAA and British Airways (BA) earlier this week.
BAA said the trials had been designed using lessons the company had learned from the security and baggage delays faced by passengers at other terminals over the past few months.
http://www.youtube.com/watch?v=VQOTg8qoYb8
Imaginary flights
A spokeswoman said: "We've been learning from the experience over the summer.
"We want to make sure the terminal is safe, secure and works like clockwork before we open, and we need volunteers to help us do that."
The first four weeks, which according tothe website are booked up, involve groups of 30 to 100 people being marshalled through the airport.
But leading up to the building's opening, BAA will be looking to use groups of up to 2,250 people to try out the facilities as if they were operating live.
Each participant will be allocated an imaginary flight and then required to act out their particular passenger role.
Earlier this week, BA chief executive Willie Walsh said: "Terminal 5 is a fantastic opportunity for British Airways and will transform our operations, with less queuing, faster baggage systems and better punctuality."