@a_pilot
This obviously bugs you, but a trifle overstated point, if I may say so!
Even while closely studying the engine instruments during a start for example, one can easily see and hear the other pilot clicking the chrono, or doing anything else. Most of us don't have tunnel vision, but keep an overall visual and audio 'picture' of what is going on around us.
But the reason why doing something non standard might be noteable is because anything outside SOP's at a critical moment is a possible cause for the other pilot to wonder if something is happening that they've not noticed - in which case it then might distract them away from the task at hand; "Why is he doing that? What did I miss?".
I thought we only had to time light up when doing manual starts? One cannot keep a cumulative record of starter useage with the (Airbus) chronos - they reset to zero every third click. I think the aircraft clock chrono can record accumulative time, but I have never seen anyone use that for engine starts.
PS, Why do some call it light off?, surely light up is more descriptive - the fuel has ignited?
Last edited by Uplinker; 17th Apr 2016 at 14:15.