Do the police automatically hunt for you if your miss your permit exit date? Or did someone call the police on them?

I hope it's automatic. It is when you fail to close a filed, open flight plan. If you don't close and they can connect to you by phone they start searching for you.

There's a huge difference between hiking and flying an airplane. Airplane trips almost always end at airports.

What if the hikers just forgot to check in when they finished their hike? Some of the ranger stations are many miles away from the trailheads and the ranger stations are not open 24 hours a day. Something important information is missing from this article.

"Airplane trips almost always end at airports". It's the ones that don't that trouble me. :P

More seriously: I did have a friend die last month while hiking in Southern California - it was heartbreaking. He fell, and died instantly - but that is not always the case. It took quite an effort to locate him - several days with multiple search teams - even though he did leave a hiking plan with his permit. Hikers do not always follow a strict plan while in the wilderness - but it is always, always a good idea to provide details about where you're going, and checking in when your back - if you're in a place as rugged as the Sierra Nevada.

More information from the Tuolumne County Sheriff's Office: Web Link

To the questions on the thread:
The US Forest Service will not automatically look for you. They do check trailheads and the license plates there (because people abandon stolen cars). If you're taking a trip, tell someone who isn't going what your plan is and when they should call for help if they haven't heard from you. Give that person details of your trip and the location of the nearest ranger station.

I've backpacked Emigrant out of Kennedy Meadows every year for decades. Wilderness Permit is required for any overnight stays in the Wilderness areas. I get my permit on the inbound drive, at the Pinecrest Ranger Station on Hwy 108, about an hour still to the trailhead.

You tell the Ranger where you are going, how many in your party, and when you plan to come out. There is no obligation or expectation to let them know when you actually exit, though they welcome post-hike comments on trail conditions, bear sightings, or other observations. My return drive is usually in the evening, after the station has closed, so I've never "checked-out."

A few times, mainly holiday weekends like July 4 or Labor Day, there have been a couple Rangers hanging out a mile or three up the trail, asking to see the permit-copy. I've heard they'll issue a permit on the spot -- I haven't heard of any arrests.

From the Facebook link in an above comment, looks like County Sheriff was notified by a relative when the party was a full day overdue. That's always a judgement call, based on the hikers' experience level and factors like the weather in this case. Would be interesting to hear from the hikers on whether they regard the worry and search expenses as warranted. @Barry, excellent advice, perhaps implemented perfectly in this instance.

p.s., the comparison with flight plans is understandable. Yes, flight plans do need to be "closed". Otherwise authorities begin hunting for your plane when 30 minutes overdue, first by telephoning the destination and nearby airports and every contact-number they can find for you, then the search parties go out along your planned route when about 90 minutes overdue. Of course you can simply radio Air Traffic Control enroute and tell them you'll be late and by how much. Flight plans are generally not required for fair-weather fliers, even at night. Subject for a different thread or other websites entirely...

always amazes me to hear people getting caught off guard by weather -- while the weather can change dramatically in the Sierras, if you're wise you'd check proper weather reports before hand. Glad they're safe- but cmon folks, it ain't hiking the Dish