I always use hand signals for a pushback whenever there is a thunderstorm warning in place.
Using a mobile phone for audible contact during push back is madness, and then you can’t be wearing the one very important item of personal protection equipment, your ear defenders!
So picture this; one hand holding mobile phone, the other hand for hand signal to pushback crew, while trying to cover your other ear with your shoulder and shouting down a phone that you can’t hear the pilot over the two or more engines.
Standard hand signals are to be used by all in the event that the primary method is either unsafe or unserviceable.
bfsalphaone