They have changed the assessment day since I joined.
There's no group exercises any more - there's a tech questionnaire, tech interview with a pilot and an interview with HR too.
Dress code is smart casual, so trousers, shoes and shirt but don't bother with the tie!
If you've got the book 'Ace the Technical Pilot Interview' - a lot of the questiones are lifted from there.
Expect the usual questions about why you want to join etc. Pilot will ask you about your current aircraft, JAR-OPS, decoding METARs etc - all day to day stuff you should have a good idea about.
