eli5 Why are instruments in plane crashes recorded in investigations?

Question

I’m not sure if this is still common practice or not, but why are/were plane instruments noted in their final positions when investigating an accident?

Would these dials not be tossed around like crazy during an accident? How do investigators know the dials are in their final positions from reading the information and didn’t just land in those positions during the accident? Do the instruments not move around more than I think?

In: 3

Answer 1

An instrument with a needle in a severe crash the needle would make contact with the gauge face leaving a mark indicating its last good position. This would let investigators know the status of systems on board.