Meet Janet

Airline callsigns seem to fall into two categories. There are the ones that are simply the airline's name — "Lufthansa 732 Heavy" or "American 1094."

And there are the more elegant callsigns, like "Speedbird" for British Airways flights, Aer Lingus' "Shamrock," or "Dynasty" for China Airlines.

Then there's "Janet."

It's a callsign shrouded in mystery, for an airline that really isn't an airline, with a fleet that bears no logos, based in plain sight of everyone flying into, driving by, or sitting in a hotel room overlooking Las Vegas' McCarran International Airport.

Janet has an airline code and flight numbers that can be tracked just like regular commercial planes. It takes off and lands with the regular civilian traffic taking people into and out of Vegas. But you can't buy tickets on it, and you most certainly can't fly on it — unless you are a US government employee or contractor with a very, very high security clearance. Janet isn't even its real name. In fact, it does not officially have one.

And what it does, as far as we know, is ferry people to some of the most secret government sites in the US.

It does so with a fleet of a half-dozen non-descript Boeing 737-600s, plus a few Beechcraft 1900s and King Airs, which can be seen on the LAS ramp in front of a simple terminal building, in a highly secure compound.

Secure, because the fleet's destination is often the fabled Area 51, on Groom Lake, a short 25-minute flight from LAS.

Area 51, also known as Dreamland, has been home to "black" or highly secret aviation programs dating back to the 1950s. It's the place where high-flying U-2s and Lockheed A-12s were secretly flight-tested. That's where the F-117 Nighthawk stealth attack aircraft was flown and hidden from view for years, before its debut in the 1991 Gulf War.