Ms Ethna Brogan:

It is not illegal to overbook a flight, which is something that had become fairly widespread practice in the industry in the past. The original regulation from 2004 set out to address this issue, but there are still instances where airlines, for various reasons, might overbook a flight. Where a passenger is denied boarding, Article 4 of the new regulations sets out the obligations on the carrier in terms of what that passenger is offered. The airline must, for example, seek volunteers to forgo their seat but if no volunteer is forthcoming, a suite of rights then comes into play in respect of the passenger who is denied a seat. He or she must be offered an alternative flight, rerouting and so on. This issue is dealt with specifically in the regulation, but it is not illegal to overbook a flight. Overbooking can happen for a number of reasons.