Assesment
I had an assessment a few months ago now and I was unsuccessful. I felt like I had a strong day interview and Sim included, I just guess wasn't what they wanted. Admittedly I do have 1 ATPL exam fail. I got absolutley 'tanned' by the interviewer but I guess they're looking to see you under pressure.
The best advise I can give is not to get hung up over the tech questions which pop up here and there as I was asked none of them. One of my questions involved engine development since the 1990's throughout the Boeing series right up to 787... With regards to the sim it varies depending on the examiners mood. I could have performed better, but maybe a different day different instructor may have been successful, you just don't know and your cannot preempt anything.
My sim as PM had an engine fire and I had an engine failure on the go around as PF after flying a CDFA approach.
You just have to approach the interview as any job and just do what you can. I don't like people who b@tch in moan about the assessments as generally they are fair although I can to a point agree with the argument that if you have a strong partner this can only help your cause.
I wish those who are going for interview the best of luck and just relax. Hopefully I will get a second chance...