LIVE* ATC air traffic control audio & radar over the skies of Atlanta and Hartsfield-Jackson International Airport

From your friends at ATCMonitor.com. © 2006 - Reproduction without permission is prohibited.

How many times have you arrived at your departure gate only to hear "There has been a delay"? Occasional delays are usually an unavoidable part of air travel.

There are many reasons why flights are delayed. Some delays are for obvious reasons, such as the fact that the aircraft hasn't arrived at your departure gate, while other reasons could be more complicated such as maintenance or equipment related issues.

By far the greatest contributing factor to a delay is bad weather. Officially, a "delay" is defined as a flight that is more than 15 minutes beyond the scheduled departure/arrival times published by the airline. However, there is no "standard" time between any departure or arrival points, because the airlines determine how long it will take, and that varies by airline, by time of day, by marketing strategy, and a host of other issues. In fact, most airlines are scheduling more time into their flights, knowing that the air traffic system will often not allow direct routings, or will involve Air Traffic Control (ATC) holds or flight slow-downs.

The Federal Aviation Regulations (FAR) were created with one principal goal in mind: to protect the traveling public. Commercial aircraft have strict rules and regulations about operating in the vicinity of bad weather. Aircraft typically cannot take off unless the visibility at the destination airport is forecast to be at or above a certain distance, usually one-half mile. Moreover, airlines are cautious about aircraft operating in the vicinity of bad weather due to passenger injury. Generally, two-thirds of turbulence-related accidents occur at or above 30,000 feet. In fact, 46 percent of all passenger injuries in flight are due to turbulence encounters, and since 1985 have cost the major airlines more than 37 million dollars in personal injury lawsuits, according to the Department of Transportation. This issue alone would seem to leave most airline operators with no choice but to delay flights when turbulent weather approaches.

Typically the spring and summer months of the year are the worst for bad weather delays as reported by the Department of Transportation. These months carry hot humid air, which produce dangerous thunderstorms, severe lightning and turbulence. In fact, thunderstorms could contain all of these hazards in one package. Air Traffic Control (ATC) may stop traffic for hours due to bad Weather, which can not only affect your departure flight, but it can affect flights that are hundreds of miles away as well since one aircraft might fly up to 6 different flights in one 24 hour period.

Bad weather also wreaks havoc on departures. Have you ever wondered why your aircraft is sitting at the end of the runway waiting for departure while other aircraft are departing? During departure, aircraft are typically routed to a specific navigation point, called a "departure fix".   If thunderstorms or other bad weather are lingering around this fix location, or elsewhere along the route of flight, or even at the destination, air traffic control will not permit departures to the affected area.

Whenever there is weather in a major airport area or somewhere in between that is holding up aircraft departing and arriving, there becomes a chain reaction of events, like falling dominoes. This reaction can affect flights that are hundreds of miles away. An example of this would be a flight from Dallas Fort Worth (DFW) to Atlanta's Hartsfield airport (ATL). Let's say there happens to be a line of weather extending from over the Great Lakes down to northern Kentucky. This weather should not have any effect on the flight from Dallas to Atlanta. Or so the normal passenger may think.

While you are checking on your ticket or preparing to board your aircraft, flights that are going into Chicago and other Northeastern airports are being rerouted around that line of weather. Air traffic controllers are sending the aircraft south around the south side of the weather system right into the same area that your flight from DFW to ATL is operating. These large numbers of aircraft going south of this weather are not usually down this far south and are mixed in with the normal flow of aircraft in your area. This produces what air traffic controllers call "sector saturation."

Sector saturation occurs when there are too many aircraft for the controller to safely handle at any given time. At one level, the US Airspace system is broken down into intricate sectors of airspace in which controllers work their assigned sector. Air traffic controller's work hand in hand passing aircraft from one sector to another keeping them safely separated. Some sectors can be very large in size spanning a distance of 300 miles or so, while others are smaller spanning 50 miles. With lots of aircraft being diverted from one sector into another to avoid weather you can have a lot of aircraft in these areas at one time, therefore making it very complex. When sectors become this busy, they are effectively closed out to other aircraft in order to regain the stability of the sector (read "A Typical Arrival Rush into Atlanta" to see how sector saturation can occur without warning).

When a sector is on the way to becoming saturated, FAA managers are watching and taking steps to mitigate the problem. The situation is monitored by an overlooking group of controllers called Flow Control. They monitor the air traffic system and delay aircraft on the ground whenever these types of situations occur in the system. While one of the main goals of air traffic is efficiency and without delay, the ultimate goal of the air traffic system is safety. When increasing amounts of weather begin attacking the US air traffic system, delays are unavoidable and the effects will be on a much larger scale than most passengers might expect.

Even in the jet age, everyone is at the mercy of weather. Delays cost airlines more than $6.2 billion in operating expenses in 2004. The national average of airline delays due to bad weather was almost 69 percent (nearly 310,000 delays) last year, especially thunderstorms in spring, summer and fall, according to the FAA. New York's La Guardia airport accounted for 29 percent of those delays.

The Air Traffic Control system is under constant upgrades to keep up with the latest technology to overcome delays due to bad weather. Weather radar has improved significantly in the past 10 years. Although there is no short answer on how to avoid weather delays, here are some tips that will decrease your chances of having significant delays:

Always take direct flights; fewer stops mean less chance for delays.
Research the airlines on-time ratings and use the airline with the best rating.
Take early morning flights. Early flights are less likely to be delayed because convective activity usually occurs later on in the day with the heating of the sun. If you are delayed, you'll have more options remaining through out the day to complete your trip.
Avoid the last flight of the day since a delay might force an overnight stay.
If your flight does get canceled, check at the reservation counter, however, if there are long lines of people waiting at the counter, call your airline's reservation center directly to book another flight instead of waiting in line for an agent. See if they can guarantee you a seat on another flight.

You might be inclined to complain the next time your flight is delayed because of weather. But consider the alternative. The United States airspace system has the best safety record in the world because of the Federal Regulations that protect the flying public, and because air traffic controllers and air traffic managers work meticulously to work weather related problems before they bring the system to a halt.

The next time nasty weather is around, visit ATCMonitor.com and watch and listen how controllers handle weather related problems with ease.