WASHINGTON – Several times a day, air traffic controllers carry white plastic buckets full of thin pieces of plastic into Washington National Airport’s new state-of-the-art control tower.
There, another controller places computer printouts, which contain details about incoming and departing flights, into the plastic sleeves and arranges them on a counter.
When a plane takes off, its slip of paper is sent down a 200-foot chute from the control room to the radar room in the basement. Another controller then totes the plastic holders upstairs to be reused.
The procedure is part of a 25-year-old system still in place at National Airport, which handles more than 310,000 flights each year and has come under criticism in recent months because of equipment failures.
While officials said there is no more efficient way to transmit the flight data from controller to controller than the little strips of paper, other systems, like the radar that has failed on five occasions since the tower opened in April, is being upgraded.
“The heart of the system,” as FAA spokesman Bill Schumann calls the radar room at the base of the control tower, is known as the Terminal Radar Approach Control system, which tracks aircraft within a 55-mile radius of National.
When an aircraft comes within 12 miles of the airport, its information is transferred to the tower and it is directed from there. A departing flight’s information is sent back down to the radar room via the chute when the aircraft is one mile away.
The radar room will be filled with light once it receives the upgraded equipment, but for now, the only light is the pallid glow emitted from the assorted computer and radar screens lining the walls. Controllers keep the room dark because when hit by light, the circular screens of the antiquated yellow and tan radar scopes take on an orange glare and cannot be read.
The scopes display green blips floating on a black background that indicate the locations of planes in relation to the airport.
Each blip contains coding that designates which airline the plane belongs to, its altitude and other tracking data.
The scopes have failed both individually and as a set for various reasons in the months since the tower opened in April. During these failures, controllers lost either the flight information for the aircraft or the background map of the airport would disappear and the blips representing the aircraft would drift randomly across otherwise blank screens.
Days after the opening, all of the radar screens went totally black for a matter of seconds when leaking rainwater shorted out communication lines.
Portions of the system went down on four other occasions and the backup systems kicked in immediately. None of the failures posed any danger to passengers, officials said, but delays sometimes resulted.
Schumann said most of the failures are in the electronics of the radar. For instance, a portion of National’s radar system failed in June when there was a problem with a computer circuit card.
In early August, FAA officials suspect a lightning strike damaged two more circuit cards, causing part of the radar system to fail again. In both incidents, controllers switched to the Andrews Air Force Base radar system.
A portion of the radar failed again in late August and initial attempts to switch to the radar at Andrews failed as well.
To avoid this situation in the future, MCI, which has the contract to provide telephone service to the airport, created a dedicated line between Andrews and National to bypass the jumble of military and other switches information has to pass through. The line is expected to be fully operational next month.
“We have implemented a strategic plan that includes a redundancy or backup system,” said Boyd Archer, air traffic manager at National Airport. “This affords us a level of safety that would make a major outage a minor inconvenience to our system users.”
The radar scopes themselves have been refurbished — taken apart, cleaned and had their parts replaced. Some are still being “burnt in,” or tested for one month before they are moved into the radar room.
Also being tested is a display unit for the Standard Terminal Automation Replacement System. National is scheduled to receive this system in 2001, but it may install the display units in June as part of an interim solution to the radar problems until the full system arrives.
The STARS displays have more color, making it easier to differentiate between arriving and departing flights, and they can be seen clearly with the lights on.
The entire STARS system will bring new computers and software in addition to the displays. It will replace the vacuum tube-operated system in place now, which dates back to the early 1970s.
Also in June, National will install a digital radar to replace its current analogue radar. This will allow more information to be transmitted at once in a more reliable fashion.
Already, new equipment has been moved into the tower’s control room, including the doppler radar display that warns of possible windshears, or microbursts of wind, that could disrupt the landing of incoming flights.