Hey Pedromari,
I recently had an assessment with Air Atlanta for NTR747 FO position. Therefore I can give you a quick feedback.
It was 6 of us out of which 4 were super experienced 50+ guys working at legacy airlines for the past 30-35 years at least. Very pleasant atmosphere, all starting with a quick company review. They are looking for 70 new pilots at the moment, and moving all 747 out of passenger operation and use them purely for cargo. Next 23 ATPL questions, very basic ones, we had 30 minutes to complete. Followed by SIM on a FNPT 737 NG. Session was 30 min PF and 30 min PM. They are looking for good CRM other than flying skills. Task was to fly out raw data SID from MUC, chasing some radials, ILS approach, no failure, no GA. And finally personal interview, which is a friendly chat about you and the company. Results will received same day.
Two contracts available. Fix roaster which is not usually offered immediately: 3 ON 2 OFF, and WW (worldwide) which is basically you tell them when you're available and they decide if they use you or not. No base salary, you only get paid when you're at base, being positioned to base and from base, and when on duty. No fix base basically but they operate many flights from Jeddah. You will be staying in 4-5 star hotels, and get per diems of 75USD/day on top of daily rate which is depending on your experience which is around 300 USD below 5000 hrs for FO.
Some pages earlier you will find a quite detailed explanation about the company and their operation.
Good luck!