Fill in application form with a couple of written answer parts, then online tests. Was then invited to assessment day. They put us up in this really nice hotel, included breakfast (feel like it should be expected, but others I've been to didn't) and arranged transport to the centre. The day consisted of a 10 minute (not a second over) presentation on yourself, directly followed by competency interview. Then, there was a numerical reasoning exercise (like online), and then a group exercise. We then had lunch where we talk with the assessors (you're still being assessed at this point too!) and finally a technical interview, mostly relating to the position you applied for. Finally, we got a tour of their historical exhibition type thing, where they have some of the classic 1920s cars and their jet engines including merlin and trent series. Although a long day, they make you feel very comfortable and you get a fair bit of time to chat to the other candidates.