United Airlines allows children aged 5 to 14 to travel alone on nonstop flights through its Unaccompanied Minor Service. The service costs $150 each way for up to two children. I confirmed the full process by calling (831) 298-4213, and the agent explained that kids are escorted by staff from check-in to arrival. Parents must remain at the gate until the flight departs, and ID verification is required at pickup. Connecting flights are not permitted for minors traveling alone.