I have seen several Western Diamondbacks from safe distance, but I had very scary close encounter with Arizona Black Rattlesnake (Crotalus cerberus). Rattling and loudly hissing, just next to me.
That one is smaller (< 3ft), little bit less aggressive and little bit less poisonous.
It scared a s**t out of me anyway!
I was far away from civilization in AZ woods, no phone signal.
I do not know if I could make it out of there alive?
New iPhones have satellite comms if you have no cellular signal. I carry a Garmin InReach Mini with me when I’m out of cellular range. It has an “SOS” button on it that communicates to a Garmin center and they contact you for info, then dispatch Search & Rescue. It can still take some time for S&R to get to you depending where you are.
That young woman died on the mountain in New York State in January. She had fallen, called on her phone at 2 pm, S&R was dispatched and, when they found her at 9 pm, she had frozen to death.