Military radios have a Guard button. Press or turn it and the radio goes to 243MHz. No channeling required, no visual contact with the panel. I always wondered why civilian radios don't have such a feature for instant 121.5.
Many times I would have liked to have it, or a button for the transponder. Nowadays we have it for the ELT at least, although if we have the old ELT it does not do much.