I find it very strange Erin was going to check out the park before taking Mom to visit. it just seems like a lot of trouble to go to, paying fees etc, when she had been at the base a while and would surely have been familiar enough with the desert to know if it's somewhere she'd want to go visit with mom, or not.
To be honest, I also find it strange that her husband wasn't more alarmed when she didn't come home that night - given that some family say she has a bad sense of direction and her last known destination was a blazing desert.
I think we've talked the possibility of whether someone would do that, and I have to say I find that not the least bit strange that someone would drive for an hour to check out a planned destination with others that they were leading. I happen to like to drive alone, and meander about, and I would do that for sure. There are others who say are you kidding you can research it on the internet, but fact is, you really can't.
Your second sentence has been something I think we all ponder. Under what circumstances do you NOT report that someone doesn't return from an outing in the expected timeframe?
1. you don't know they haven't returned ?
2. they frequently don't return X
3. they've made it pretty clear they may not return today ?
4. you don't care one way or the other if they're gone X
5. you're afraid if you report it will be discovered publicly they are doing something illegal or embarrassing when found (don't know how to characterize this one)
6. you're paralyzed by fear and reporting would make it all too real ?
7. you don't want to draw attention to yourself in a military type setting by reporting your wife hasn't returned home ?
8. you know for sure where they are ?
X = doesn't seem possible ? = don't know how possible
Any more reasons?