A job left halfway should not look like a job finished
Context
Aircraft pushback at the gate. The towbar connects the aircraft to the tug. Once the aircraft is moving, the headset operator is the only person in contact with the flight deck.
What happened
The bar had been staged by someone else and the connection was never completed. In that state it looked the same as a finished job. The first sign anything was wrong was the aircraft moving on its own, faster than it was being pushed.
What I changed
I told the flight deck they had the aircraft and asked for a smooth stop, while I still had the headset. Since then I verify the connection myself before a push, whoever staged it.
Result
A halfway job that reads as a finished job is a design problem before it is a people problem. Where the wrong state and the right state look alike, looking is not checking.