Michael Ball's research is aimed at helping airlines get in and out of airports with maximum flexibility and minimum delays.

Ball is a professor with a joint appointment in the University of Maryland's Smith School of Business and Institute for Systems Research, where his expertise in network optimization is translating into fewer flight delays and better ground operations at dozens of the nation's busiest airports.

Ball, along with colleagues in the National Center of Excellence for Aviation Operations Research, or NEXTOR, is pioneering the use of "collaborative decision-making" in air traffic systems to ease dreaded flight delays and cancellations caused by bad weather, equipment failures and other unforeseen problems. In other words, he's helping planes land and take off when they're supposed to, something the Federal Aviation Administration and the airlines have struggled to do since deregulation opened the skies to more planes, more routes and millions more passengers.

When Ball talks about air traffic systems, he talks in terms of "slots"--the highly coveted landing, taxiing and terminal rights that airlines have at airports around the country. On any given day, airlines fill up their slots like clockwork, as illustrated on the ubiquitous arrival/departure boards in airport terminals that tell passengers what flights are arriving, departing and in the gate.

The problem, Ball says, is that during busy periods at major airports, there is far more demand for arrival and departure activity than there is runway and terminal space to accommodate planes. As a result, the airlines must take turns, and each turn is called a slot. Ball's work is about helping airlines and FAA traffic-flow managers get planes to use their slots with maximum efficiency. "There is a limited resource there, and that resource has to be rationed out," he says. "When you have a congested airport, every slot becomes extremely valuable. You want to ration them in such a way that the airlines have optimum flexibility in making it work."

Collaborative decision-making, or CDM, works something like this: Let's say it's raining buckets at Logan Airport in Boston at 2 p.m., and the rain is expected to continue throughout the afternoon. This reduces the airport acceptance rate, or AAR, at Logan by half, from 60 landings per hour to 30. Meanwhile, between 5 and 6 p.m., Logan has 50 flights scheduled to touch down. As planes slotted for 5 to 6 fall back into the 6 to 7 p.m. slots, airplanes scheduled from 7 to 8 back up as well.

When the system gets severely backed up, due to major weather systems or just heavy traffic, delays begin compounding on each other, and entire parts of the air traffic system can be knotted up for hours.

"Things have been getting worse," Ball says, "and the cost of those delays by any measure is in the billions of dollars."

To compensate for Logan's slowdown, the FAA might initially propose delaying the take-off times of flights headed to Boston from other cities. American Airlines flight 1872, for instance, might be placed on a 15-minute delay from its planned departure from Washington's Reagan National Airport. At the same time, American flight 1372, departing from Chicago's O'Hare Airport, might receive a 55-minute delay. Under CDM, the airlines are given the flexibility to reallocate those delays, or even switch them, so that a priority flight from Chicago won't wait longer than a commuter flight from Washington. The airline could make all kinds of other complex adjustments as well--canceling a 15-passenger flight from upstate New York, for instance, to free up a slot for the Washington flight. This kind of aviation musical chairs would continue as long as the weather persisted, allowing airlines to reduce delays for a long string of flights.

While the basic ideas sound simple, underlying collaborative decision-making are complicated resource-allocation procedures that ensure all airlines are treated fairly and that delays are kept as short as possible. More advanced forms of CDM being developed by Ball and his research team involve complex forms of "slot exchange" that make use of auction and optimization theory.

Ball says CDM was slow to take hold at first, in part because the FAA has been rigid about how slots are allocated, but also because airlines were reluctant to share information with regulators for fear that one airline would be allowed to capitalize on another's misfortune.

Since 1997, when CDM was first implemented at Newark, N.J., San Francisco and then other airports around the country, the concept has drawn positive reviews by many in the aviation industry, including airline executives and airport managers. Last March, NEXTOR sponsored a two-day workshop at the university where researchers joined government and airline officials to pose new questions and ideas for further improving the air traffic system.

"The key to meeting demand is communication and cooperation," Steven J. Brown, acting associate administrator for air traffic services at the FAA, told the conference attendees.

The FAA, once viewed by the airline industry as an obstacle to reform of the air traffic system, has embraced collaborative decision-making, ceding some of the agency's control over landing slots to the airlines themselves.

"They're less involved in the airlines' business," Ball says of the FAA. "Rather than trying to control every individual flight, they're working at a more system-wide level" where regulators can facilitate air traffic flow rather than micro-manage it.

Ball is quick to point out, however, that CDM is strictly about flight scheduling and on-the-ground airport operations; it does not call for scaling back the FAA from in-flight air traffic control, where Ball says safety remains "an absolute and uncompromising concern" for airlines and regulators alike.

Ball says it may take several more years to determine just how effective collaborative decision-making is at easing congestion, but he says there is mounting evidence that the concept works, even if airline passengers aren't yet noticing the change.

"The thing that's been easiest to quantify is a substantial improvement in information accuracy" between airlines and flight regulators, Ball says. But "everyone suspects that the biggest benefit is that the airlines will have all this control, so they can optimize their schedules better."

And is Ball, a frequent flyer, spending less time sitting idly on the taxiway? "Oh, absolutely," he says with a grin. "Absolutely." --DC

For more information on Ball's research, visit NEXTOR's Web site at www.isr.umd.edu/NEXTOR/

Parrot Poaching PUTS Many Species AT RISK

A new study by a University of Maryland researcher shows for the first time that poaching of wild parrots from their nests to sell on the world pet market is leading to endangerment and possible extinction of many species of the exotic bird.

Timothy F. Wright

The study, led by Maryland postdoctoral fellow Timothy F. Wright, shows that despite laws prohibiting the stealing of parrot chicks from their nests, poaching is a significant cause of mortality for many of the parrot species found in the American tropics.

"Parrots are among the most highly threatened birds on earth, with more endangered species than any other bird family," says Wright, whose latest research was published last May in the journal Conservation Biology.

The research report shows that 46 of 145 species in the neo-tropics are at risk of extinction from habitat loss and poaching, and that poaching alone affects 39 species and is a greater cause of mortality than natural causes.

Wright's team, which represents 14 countries, analyzed data on parrots collected in Central and South America and the Caribbean between 1979 and 1999. Wright's work was funded by a grant from the University of Maryland Biology of Small Populations training fund.

According to several earlier studies, between 400,000 and 800,000 parrot chicks were taken from the wild each year between 1991 and 1996--and those estimates may be low. Wright fears the full effects of poaching might not be apparent yet. "Parrots only breed once a year, and they may live for 50 years," he says. "Without young birds to reproduce, we may see the number of parrots drop dramatically and suddenly."

Some groups interested in the conservation of parrots, including the American Federation of Aviculture, have discounted the threat caused by poaching, arguing that removing birds from the nests of endangered populations actually helps the species. They say parrots can be raised in captivity, then released into the wild. But Wright argues that "dumping parrots back in the wild" has less benefit for them than for some other animals.

"Parrots are a lot like humans and dolphins," he says. "They are dependent on learning how to survive from their parents when they're young--how to join in the flock, what sort of trees to nest in, what to eat. Parrots invest a lot of energy in teaching their offspring."

The market value of parrots, combined with the ease of capturing them, make them attractive to poachers, especially in poor countries. A bird can bring an average of between $500 and $1,500 to a seller on the retail market. The rarer the bird, the higher the price, which increases even further the threat of endangerment of the species.

"People will take amazing risks to get these parrots," says Wright. "Some of them just throw lassos up the trees to the nests and climb up. Others are more organized. They wear spurs, like the ones telephone linemen use, and scamper up the tree. They might make only 10 or 20 dollars for each bird, but that's worth a day's wages for a field hand in Costa Rica." --ET

For more information about Wright's research, visit his Web site at www.bsos.umd.edu/psyc/dooling/hometim.htm