475,000 Takeoffs and Landings a Year
The Summer Games will bring 4,000 additional aircraft to London's airports. Find out what it takes to keep Heathrow running smoothly on a normal day.
- By Michael Milstein
- Air & Space magazine, January 2007
(Page 3 of 5)
Two ground controllers—airport traffic cops—weave 747s between and among A330s. Multi-lateration radar triangulates on each airplane’s transponder signal, showing each as a radar dot while still on the ground—even behind buildings. It helps controllers work them out of dead-end cul-de-sacs amid terminals built for small airplanes like Hawker-Siddeley Tridents but quickly clogged by modern airliners twice as wide.
A jumbo pulling out may gridlock other airplanes for five minutes or more, and start blocking taxiways. Controllers know almost every patch of spare tarmac where they can put airplanes to sit and wait, but, says Phil Layton, Heathrow’s air traffic control manager, “There’s less and less places for us to hide them.”
A fourth terminal was built on the far side of the southern runway when space ran out in the airport center; to reach it, airplanes must scoot across the runway between the takeoffs and landings of others.
Moving airplanes gets easier at night, when controllers use a touch screen to turn on lights in the runways. Controllers tell pilots to “follow the greens,” illuminating a line of green lights along the right path. Red lights across the taxiway mean “stop.”
The time between each takeoff is known as a “Heathrow minute,” and in the tower, the goal is to shave it to the bare minimum. Jetliners take off as close as a minute apart, as long as they follow different routes so there is no risk of one catching the other. Controllers shrink the minute even further by craning their necks and watching for an airplane’s wheels to lift off the pavement. That’s when the next aircraft goes.
“At Heathrow, we call that a minute,” says Paul Hooper, a tower supervisor. Then he grins. “Depending on the airplane, it’s probably a bit less than a minute.”
It is the most critical timeline at Heathrow. There is a constant campaign to keep pilots from dawdling on the runway; if each airplane throughout the day wastes a few seconds, it adds up to a few airplanes getting stuck when the nighttime flight curfew shuts down nearly all operations. Stephen Mathewson, a former engineering professor who got bored by academic life and joined airport owner BAA as an internal consultant, went to great lengths to measure how fast pilots get on and off the runway. He posted traffic police at the end of the pavement with radar guns to clock the speed of each airplane. Later he turned to ground radar to track each pilot’s habits.
Then he crunched the numbers and showed each airline how its pilots were doing. Soon, slowpokes picked up their pace. Virgin Atlantic worked timing into its simulator training. Pilots set their brakes to make better use of high-speed runway exits, which are angled so airplanes can turn off at 50 mph. That adjustment shunts them out of the way faster—arrivals average 50 seconds on the runway. No one wants an airplane poking along, sitting in the way, or braking too late, missing its turn, trundling to the next exit—a time-waster.
“Most professionals want to behave ably,” says Mathewson, who finds himself part efficiency analyst and part psychologist. “You don’t need to force them. You just need to raise their awareness that this is an issue, and they can help.”
The airport spent about a half-million dollars building a temporary exit next to one closed for eight weeks of reconstruction. Otherwise airplanes would have had to coast 500 feet farther down the runway before turning off, which would slow the landing rate.
“This is the business of teasing the edges,” says Richard Smith, a lanky, intense man who helps plan the future of the airfield. He likens Heathrow to a giant aircraft carrier. When he started, after getting turned down for pilot training nearly 30 years ago, 900 airplanes were taking off and landing every day; now 1,370 do. He knows the angle of each taxiway, which affects which way airplanes can turn, which in turn affects how long they take to reach the gates. He knows which airplanes fit at which gates, and how juggling gates at the last second sends ground crews dashing through the airport.
In certain places, 747s park nose-out so their tails do not block signals from the instrument landing system. Workers are tearing down a few gates so the new double-deck A380, the world’s largest passenger airplane, has room to pass (see “Superduperjumbo,” June/July 2006). The airport is counting on the airplane to pack in more passengers. But air traffic controllers are starting to scream about all the construction.
“They have said to us, ‘We’re getting to the point we can’t maintain the movement rate, not because we can’t use the runway, but because we don’t have the taxiways,’ ” says Smith, racing around the airport in a white car with a flashing light on top. He eyes a taxiway that is a quilt of concrete patches. “The problem is keeping Heathrow going under all this pressure. We spend huge amounts of time and effort making sure this place doesn’t fall over, and it doesn’t happen by chance. It works because the place collectively works as a team, by design or by default. And it’s not all by design.”
An American airliner appears in the rear-view mirror: “I’ve got to keep an eye on that one,” Smith says. “I don’t want to get run over by a triple-7.” Computers match airplanes to gates, he says, but it’s not a simple process: Arab aircraft cannot be parked next to Israeli ones, for example.
Then he sees airplanes parked in a lineup of gates that causes him to chortle: American Airlines 777, United Airlines 777, American 777, United 777, and Iran Air 747. “Well, gee, Mr. Bush! Clearly one of the parameters in the computer is it’s okay to put the Iranians next to the Yanks,” Smith cackles. “I think that’s quite funny.”
On any given day, tomorrow at Heathrow has already started. Airplanes are on their way from Hong Kong and beyond, for an arrival the next morning. “Airlines have been told to slow up miles out because there’s no use getting here early if we have no bloody place to put them,” Smith says. It’s practical, and, as far as the passengers are concerned, “Will you notice if the airplane slows down 15 knots, or will you notice sitting on the ground for 20 minutes with the engines running?”
Once the airplanes have landed, Ian Watson juggles them, finding them places at one of Heathrow’s roughly 165 gates. The computer may plan out the day, but it can’t account for glitches—jetways break, airplanes are late, the weather is unpredictable. So Watson takes over where the computer leaves off, compensating for the unexpected. He works in a bunker-like building in the crook of two taxiways. The building would have a great view of passing airplanes if not for computer screens that block all the windows. Watson uses a joystick to scan every nook of the airport, working out which airplanes get to park at a gate, or pier. Since Heathrow has more airplanes than gates, some park out on the pavement and wait for buses to ferry passengers to terminals.
About a mile and a half from the end of Heathrow’s southern runway is the Hounslow Heath Infant School, a public preschool where cheery Kathryn Harper-Quinn is the head teacher. She loves airplanes. The sleek Concorde, which rocketed in and out of Heathrow until 2003, was “one of the most beautiful things I’ve ever seen,” she says. But the everyday aircraft, descending over the school at slightly less than one per minute, cost teachers roughly 10 seconds out of every minute of classroom time. Everybody stops talking because the noise drowns out anything they say.