Quick note (and my apologies if this is old news) for people who, like me, always print a paper boarding pass at the kiosks and think it's more reliable than anything on a phone. At ATL, DCA, DEN, EWR, LAS, LAX, LGA, ORD, PDX, SEA, SFO and SLC TSA is rolling out PreCheck Touchless ID for UA flyers (basically security via facial recognition machine only). However, there's someone checking your boarding pass before you're allowed to use the Touchless ID machines and that someone requires a boarding pass on a phone (and, of course, I couldn't bring up my boarding pass on my phone so I couldn't use the new machines). UA paper boarding passes aren't good enough because they don't indicate whether you are permitted to use the PreCheck Touchless ID machines.