What are flight attendants noticing about you when you’re boarding the plane? It’s nice to have a smiling face and friendly greeting as you enter an airplane, but it turns out there is more to it than meets the eye. Behind that pretty (or handsome) face is a first responder, trained to keep a close watch on the plane for threats, beginning the very moment you board. Suzy Strutner, contributing writer to the Huffington Post, asked flight attendants from Southwest Airlines, American, and others to name the first thing they noticed about passengers as they board. Here are some of their answers.

“I [notice] who makes eye contact with me and who doesn’t... the ones who don’t ... make me investigate.” They might be afraid of flying, or not feeling well. Perhaps they’re dealing with a personal problem. “A facet of my job is making sure everyone has a comfortable flying experience.”

“Intoxication and aggressive passengers are prime suspects we try to identify” right away. “We are trained in basic taekwondo techniques... But stopping them before they get up there is our main goal.”

“I’m looking for able-bodied persons who can assist with security problems inflight, as well as someone who appears willing and able to assist in an emergency evacuation.”

“It’s important to check if my passengers are fit to fly. Once all doors are closed, and we’re airborne, it can get very challenging to handle medical emergencies.”

“I’m searching women to see if they’re hiding baby bumps. ... After a certain point in pregnancy, women need a doctor’s certificate to travel.”

“I ask passengers if everything is alright if I have the feeling something isn’t perfect. Passengers with fear of flying get my special attention. I love to care for them and to make them feel comfortable.”