Sorry for the delay in getting back to this thread.
IGh, just to clear things up there was no incident. I quoted a comment from someone who observed a push back that, to his eye, compromised the safety of everyone onboard and on the ground because the crew used hand signals instead of waiting for a headset. Why?!
I certainly don't propose or advocate only using hand signals but I don't agree that they are unsafe.
Hand signals don't have a language barrier and are clear and concise. We are, or should have been, trained to use them and I certainly remember learning them during the ATPL ground school.
Of course I'd prefer to use a headset, it's easier and establishing communication from either end happens as quickly as electrons can move. However, headsets quite often fail during the push back. Either because they're crap, full of water or because the lead has been run over. Then you have a very real problem of communicating with the ground crew who are unexpectedly out of touch. And then you have to use hand signals and if you don't know them or are out of practice then what happens?
Out of interest our SOP is to start both engines on stand if we aren't using a headset, only then can we start the push back. Does anybody else do this?