Are you guys being intentionaly thick, and/or did some not read the whole thread.
First hand doesn't mean you did it your self, it just means you actually witnessed the event or have direct exposure to the event, its factual data or outcomes. Your knowledge is not the result of someone else telling you.
To use the examples cited - The rescue and recovery crew that recovered the submarine that went below its crush depth have first hand knowledge. Was the crush the result of going too deep, or did it go too deep because of mechanical failure and then crushed. With no likely living witnesses, that might be hard to ascertain.
The team that investigates air crashes and reviews the black boxes have first hand knowledge of what occured, at least to the extent it is recorded, factually provable and not the result of inference.
Webster's Dictionary First-hand adj or adv - from the original source; direct.
Thanks to all of those who took the time to repond to the actual question and request for information. I have all the info I require and have found the first hand accounts I was looking for.
Thanks for your help and information, I consider this thread concluded from my perspective.
