Ever curious how it works? Well, there's actually a (somewhat credible) threat at the airport in my city right now.
Well, it all starts off hush hush. To keep people calm and quiet, they don't start right off with "BOMB THREAT! EVERY MAN FOR HIMSELF" This one was originally reported as a mechanical issue that grounded the plane. A couple news outlets picked it up as a side note in their top of the hour run down. Nothing overly exciting, and it made a good cover for the presence of ARFF trucks on the runway. Standard procedure
A couple of minutes later, there's always a reporter in the area, and they start to notice things are a little different. One reported that there were planes landing but not going to the terminal. Normal for a small private jet, not so much for a 737. Twitter still hasn't erupted.
Standard Operating Procedures for a bomb threat in my jurisdiction is evacuate the areas in immediate risk, but leave everyone else where they're too. The plane in question was at the terminal at the time of the threat coming in, so they evacuated the plane, as well as the secure area of the terminal. People started tweeting they were being told to leave the secure area. More outlets started picking it up.
The increased media presence starts to notice the increased emergency services, including ambulances arriving, despite the plane stopping. The idea that a mechanical failure is at play doesn't float any more.
Word starts getting out about the bomb threat at this point, either through people hearing chatter, or through noticing major police presence, including K9 and EOD trucks. Once the airport has confirmed the threat as credible, they shut down, meaning if you were able to go elsewhere, you did, and if you haven't left, you won't. At this time too, the terminal is now completely closed (no in, no out) and the people on planes on the tarmac are not leaving. This is logistical. It takes a lot of time, man power and money to move people. If they don't HAVE to, they don't. People here are generally pretty easy going, so people are pretty relaxed at this point.
Once the airport announces it with a press release, national outlets pick up the story, and it starts to go viral.
At this point, EOD is on scene, and they're preparing to go in. Mutual aid K9 units have been brought in to resolve this issue as quickly as possible. Lots of emergency services are standing by for the worst case. If it gets bad, as in they confirm an explosive device, measures will be taken to evacuate. People aren't noticing the background noise at this point, as there's blinky lights all around, but taxis are starting to stage, and buses are being brought to the terminal for quick evacuation if needed. The entire airport is indefinitely closed, pizza has been ordered. No photo of that unfortunately.
As the EOD enters the tarmac area, the airport shuts down its "airport cameras" which show the runway, the terminal and parts of the tarmac.
Last frame on the site before they took off the feed.
At this point the K9 units are doing a preliminary examination of the plane, going over the outside for scents of explosives. They'll move into the cabin, the cockpit, and then the cargo hold, and finally the other areas in the plane that don't get a lot of traffic. They do this slowly and carefully, going on the most traveled areas first (because it's easier to drop something there, and it's probably safer, since so many people went through it). While the Dog teams look for explosives, the EOD is gearing up, waiting for the go ahead to enter. ARFF teams along with local fire department are on standby close to the aircraft, but far enough away as to not interfere with operations. The director of Emergency Services and other department representatives, as well as Medical teams and additional fire support are staged at the Emergency Operations Centre, commanding the entire event.
Evacuations at this point have been completed, which is why it took so long (about 3 hours) to actually investigate the plane for explosives. You don't want to be moving people when trying to find explosives. You run the risk of putting people in harm's way, getting wires crossed, and making things more hectic than need be.
If you watch the twitter feeds (YYT, St. John's Airport, Bomb threat, and the like) you'll see lots of people tweeting, all of them talking about how it's been orderly and people are maintaining a good attitude. This comes from careful planning of the emergency services at the airport. If the people controlling the group act calm, normal and like it's no big deal, as will the people. You'd never say there's a bomb threat by looking at the terminal, with lots of people sitting around, smiling, joking, and pizza being delivered to the masses. Emergency services present aren't using lights and sirens past the turnoff tot the airport either (except on tarmac, where required), which makes this issue seem like a smaller one.
I'll update as more comes along