D”Y, pardon my ignorance, but what is airplane mode exactly (I have an idea, but am not sure). I only have a plain cell phone (not interested in all the bells and whistles like downloading apps). SO I gather you are saying there is a mode that can temporarily disable the phone apps, so they will not be intrusive while davening.
My only other question about this is, would using this cause OTHER people to be distracted by the mere SIGHT of a phone being used for davening? If so, then maybe it could be problematic, even if halachically technically perfectly ok.