Just double checking - they were 16 and 32 ton forklifts?!?! ( not 1600kg and 3200kg??) Virtually unheard of to hear a forklift training organisation training new operators on forklifts that big....nonetheless like the previous answerer has said, almost every forklift operator has had trouble learning how to judge tilt, the best ways iv'e found is to get the forks flat/"mast vertical" on the floor and /or at eye level when your'e getting a load from the racks....also comes with experience, but by looking at the mast you should also be able to see if its tilted forwards or backwards....very hard to get it perfectly level, but close enough is usually good enough if your'e dealing with wide pallets like euro pallets, loscam and chep pallets (what we use in australia).... the thin export pallets are an absolute pain!!!

Also as much as you'd like to use something to help you leveling the forks, i'd recommend against it to start off with as its best to learn how to do it by eye in my opinion, you won't always be having perfectly flat floors in every loading/unloading scenario so youl'l have to learn to adjust your tilt backwards or forward to get flat forks (if that makes sense lol)