Wednesday, October 12, 2005

 

Flight Plans and Control Towers

When stories such as the Stolen Jet incident make the rounds, people (including the reporters telling the stories) are often surprised to find out that airplanes can take off with a flight plan being filed, or without people in a control tower noticing what's going on. Here's a little explanation of how these things work.

A "flight plan" is information filed with the FAA (in the US) regarding an intended route of flight along with takeoff and landing times and a few other interesting bits of info. A pilot is only required to file a flight plan in a couple of cases:

  1. The flight will be conducted under Instrument Flight Rules (IFR), meaning that the pilot will be in continuous contact with air traffic controllers who will monitor and direct the progress of the flight from takeoff to landing. IFR is required above 18,000 feet, and any time the weather doesn't provide sufficient visibility.
  2. The flight will be passing through airspace that requires identification of airplanes for national security reasons. For example, if you are flying through the Washington, DC area or approaching one of the coasts from overseas, you need to file a flight plan.

Commercial airline flights and many charter operations always operate IFR, but many pilots will conduct flights using Visual Flight Rules (VFR) when the weather permits, even if they are instrument-rated. Pilots who are not instrument-rated have no choice but to fly VFR. A flight plan is not required for a VFR flight.

VFR pilots may file flight plans, but the only real effect of a VFR flight plan is that if the pilot does not call the FAA at the expected arrival time to close the flight plan, then the FAA will start search-and-rescue procedures. Nobody has to give the pilot permission to take off, fly the route, or land. Nobody will be monitoring the plane's position. Nobody will notice if the plane strays from its planned route. Nobody will care if the pilot lies about arriving at the destination. Nobody will care if no flight plan is filed at all.

Now, about control towers: People who fly commercial airlines at big airports tend to expect that all airports have control towers operating 24 hours a day. In fact, most airports do not have control towers. Yes, the airports that host commercial air carriers usually do have control towers, but most small airports are uncontrolled. At many small airports that do have towers, the towers only operate during the day, and close down at night.

At an uncontrolled field, pilots usually use their radios to state what they are doing, so that anyone else listening on the same frequency can react accordingly. However, radio use is not required, and there are plenty of "NORDO" (no-radio) flights. It is each pilot's responsibility to avoid crashing into other airplanes. This might sound like a chaotic situation, but in fact, many pilots prefer this to the chaos of constant radio chatter.

At those small airports that do have towers, the responsibilities of the tower controllers are limited to giving instructions to IFR pilots and ensuring that two airplanes don't try to use a runway at the same time. The tower personnel aren't looking for terrorists or thieves, and are not monitoring flights to determine whether anything "suspicious" is going on. They just want to prevent planes from hitting one another (and the primary responsibility for collision avoidance is still with the pilots, not with the controllers).

Except for IFR flights, and flights into the busiest of the nation's airports (O'Hare, Atlanta, LAX, etc.), it is not necessary for a pilot to follow a schedule or make any arrangements ahead of time to use an airport. When the plane gets 10-20 miles away, the pilot can just call the tower on the radio and state the intention to land. The controllers need no prior knowledge of that airplane; they just fit it into whatever traffic is already landing or departing. Similarly, when a pilot on the ground calls the tower asking to take off, the controllers just give the pilot instructions for getting safely to the runway and off the ground. They don't care where the planes came from, where they are going, or who is flying them; they just want the planes to move safely through their airspace.

At night, the tower may close, but the airport is still open. Many airports have pilot-controlled runway lighting that can be activated by an airplane's radio. An airport with a closed control tower is just like an uncontrolled airport: a pilot can take off or land without talking to anybody or filing any paperwork.

So, here's how to steal a jet airplane for a joyride and get away unnoticed: Take off when the tower is closed, don't use the radio, turn the transponder off, avoid busy airspace, maintain a low altitude and low speed to avoid notice on radar, land at an uncontrolled field (or a field with a closed control tower), high-tail it outta there, and eliminate any talkative witnesses.

When you read a story about a small-plane crash, and the reporter makes a big deal about the fact that there was no flight plan filed, or that the airplane's departure or arrival were "unscheduled," or that the airport staff had no information about the airplane or its pilot, note that these are not atypical events. The government doesn't track small-plane flights any more closely than it tracks automobile trips, and most small-plane pilots consider that to be a good thing.


Comments:
Nice job! I will plan to point family and friends to your blog when the inevitable questions come up!
 
Excellent post, Kris. I hadn't even thought about people thinking that the tower controllers were watching us for suspicious activity!
 
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