New navigation systems for MDY, ORD

Have to cut & paste from the Chicago Tribune as it was available to
subscribers only :-(
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Midway's landings may straighten out
Navigation system would eliminate circle approaches


By Jon Hilkevitch
Tribune transportation reporter
Published September 15, 2003

A navigation system so precise it enables aircraft to surgically glide
through dangerously narrow passages and fjords to landing strips in Alaska
is being evaluated to get more use out of the runways at Midway Airport.

The new technology would give air-traffic controllers the tools to direct
more takeoffs and landings at Midway, especially in poor weather, according
to the Chicago Department of Aviation.

And it would eliminate the dizzying circling patterns jets sometimes fly
into Midway.

"It's an important safety improvement that would also help reduce delays by
easing the conflict between Midway and O'Hare, which share the same
departure airspace," said Kevin Rojek, president of the air-traffic
controllers union at Midway.

Planes on certain paths to the Southwest Side airport must fly circling
approaches--giving some passengers butterflies--because Sears Tower
interferes with radar signals that guide airplanes to the ground. The
pinpoint nature of the improved performance would permit pilots to fly
efficient curved approaches, instead of circling down until the runway is in
sight, and give controllers the necessary safety margins to funnel planes
more closely together than before.

"The circling approach is not real comfortable for passengers because you
are banking the airplane towards the runway a little more than in a nice
gradual approach," said Dave Lindskoog, vice president of flight operations
at ATA Airlines, which is seeking federal approval of the advanced procedure
at Midway.

In addition to reducing delays and passenger inconvenience in bad weather,
the navigational improvement could help add years of viability at the
landlocked airport that is in the final stage of adding terminal space and
aircraft gates, but cannot expand the airfield without encroaching on homes
and businesses.

The navigation system, which provides unprecedented accuracy vertically and
laterally in guiding airplanes, is also slated for use at O'Hare
International Airport as early as 2005 or 2006, according to the Federal
Aviation Administration. Flight departures from O'Hare are constrained by
the busy approach path to Midway, resulting in delays at O'Hare. The curved
approaches planned for Midway would ease the conflict between the two
airports, officials said.

The FAA is reviewing proposals to use the navigation program, called
Required Navigation Performance (RNP), in the Chicago area.

"We are greatly interested in this new procedure because it gives more
flexibility to pilots and controllers in how they land aircraft," said Kitty
Freidheim, the city's managing deputy aviation commissioner for planning and
development.

ATA and Southwest Airlines, the largest carriers at Midway, submitted the
application to the FAA to use the navigation system to simplify the special
approach paths. Alaska Airlines at Juneau International Airport and five
rural Alaskan airports received FAA approval for limited use of the
procedure in 1996.

The FAA is implementing a plan to establish widespread use of RNP through
2020, and Chicago officials and the two airlines want to be first. Freidheim
estimated that could occur as quickly as three years at Midway.

The technology would allow airspace designers to create a highly efficient
corridor leading to a northeast-to-southwest runway at Midway that today is
used by only 15 percent of flights at the airport, according to the city
Department of Aviation.

The runway, known by its 220-degree compass heading as 22 Left, is used
sparingly in part because Sears Tower interferes with instrument-landing
radar signals that guide planes along the proper slope leading to the tip of
the runway. Pilots directed to land on Runway 22 Left must now execute a
complicated "circle-to-land" maneuver that the airlines hope to eliminate.

Under Midway's circle-to-land rules, pilots line up their approach as if
they are actually planning to land on a different runway, called 31 Center,
which has an instrument-landing system that is not obstructed by Sears
Tower. Upon descending low enough for the pilots to spot the threshold of 22
Left, the pilots break off their approach to 31 Center about 5 to 8 miles
from the airport and circle to the right for a landing on 22 Left.

The maneuver, while not unsafe, is more complex and equivalent to a big
detour. It slows the flow of planes by adding minutes to each landing and
requires air-traffic controllers to keep other planes far away from the
airspace used for the circling pattern.

"The circle approach is no fun for pilots and it makes the controller's job
more complex because of the unpredictable nature of pilots circling at
different rates," said Ray Gibbons, a veteran controller at the FAA facility
in Elgin that handles aircraft arriving at and departing Chicago-area
airports. "As busy as Midway is getting, this plan is certainly worth
pursuing."

The RNP procedure, working in combination with sophisticated navigational
equipment already onboard commercial aircraft and the satellite Global
Positioning System, would allow pilots to fly a direct approach to 22 Left,
significantly increasing the use of the runway. The airport's ground-based
instrument landing signals, which Sears Tower partially obstructs, would no
longer be needed, eliminating the cumbersome and uncomfortable circling
approaches.

The RNP corridor would start near Chicago Heights in the south suburbs, take
aircraft over Lake Michigan to a point over Northerly Island, then over
downtown on a gentle curve that straightens out for an approach to Runway 22
Left, officials said.

The new RNP routing creates the highly defined path over the ground for
aircraft. Avionics in the cockpit constantly refine the path by correcting
for winds and other factors. That's why RNP has been used so successfully in
guiding planes over mountaintops to remote Alaskan airports, even if those
airports are socked in with low visibility. In Juneau, Alaska Airlines
formerly diverted about 150 flights each year because of bad weather.
Diversions dropped to about 10 annually after RNP was introduced. The
technology is also expected to boost efforts in steering airplanes away from
noise-sensitive residential areas near airports.


Copyright © 2003, Chicago Tribune