These seats are only released at the discretion of the Flight Crew, on the day. Individuals have different rest requirements depending on the time of day and length of flight. For example on a three crew flight the heavy/relief/third pilot is usually on first break and this will start 20mins after take off. If this is a morning departure when they’ve had a decent sleep then going to lie down in a bunk for three hours isn’t necessarily the most conducive method of taking a break.

On a flight such as KUL and SCL when there are four members of Flight Crew, two of these will be on break at the same time. Amongst other things, having a rest seat in the cabin reduces the chances of one pilot disturbing the other in the bunks should they decide not to sleep or only sleep for a few hours. Provided the crew member achieves the legal minimum rest requirement for that particular duty, the onus is on them as to how they spend their time.