So let's do a recap, but keep in mind, many things may be in hindsight.
1) Vid I saw there was many people hitting the deck in the terminal area and staying on the ground.
For me, that enclosed area is a kill box (see NZ mosque shooting vid if you can find it). If I hear no gun fire, I wouldn't stay on the ground, but get up and act like a full back and clear the way for my wife so we can get out of dodge after a brief assessment of no gun fire, regardless what people are yelling.
Granted not many people know what gunfire sounds like or it's relative proximity.
2) If I did hear gunfire and thought it was relatively close or see people being hit/the gunman, then that changes everything. Hit the deck, crawl toward cover (diff from concealment). Hope for a blind spot to attack. Like behind a pillar waiting for that muzzle to clear the corner, or sneak up in blind spot.
3) IDK if the gates are locked, but if they aren't then I guess you could go down the gate and if there's no plane docked, then jump 2 stories to the concrete. But what if there is a plane there blocking your egress? Odds are a shooter won't go down the gate just for 1 or 2 people. They're going to continue on their rampage. Same philosophy for locked door. Shooter isn't going to spend to much time on a locked door trying to gain entry (See NZ vid again where he jiggled the door knob then moved on). Don't forget to look out the window to see if the shooter is on the runway.
4) If I was in the check in area and had my luggage, I would not unzip my suitcase and take my gun out. Unless I really had to, like if rounds are hitting near me. Responding armed people might think I'm the bad guy.
Any other input