checking potential route changes with real-time trafc data
to determine plausible routes. Positive results are then re-
layed to an airline’s operational control center, which can
then uplink the route change request to the pilots through the
Aircraft Communications Addressing and Reporting System
(ACARS). Pilots then ask air trafc controller for the “direct-
to” route change using the normal process—over the VHF
radio. “It saves a minute or two at a time,” says Meserole,
adding that the company is now talking to Canadian airlines
about the product. American Airlines has been trying out a
similar routing tool developed by NASA that identifies diver-
sions around weather that save at least 5 min. compared to
the clearance route.
KLM Royal Dutch Airlines was the launch customer and
development partner for Boeing’s wind updates subscription
service, a feature that Meserole says “has more impact,” as it
allows the aircraft’s FMS to fly an optimal path, particularly
in descent. “We send in-flight updates to the wind profile,
picking out wind information important to that specific flight
as it reaches future points in time,” he says. “It’s a one-button
load from the pilot to the FMS.” Meserole adds that any time
there’s a wind change, the updates are sent up to the aircraft
automatically via ACARS. He confirms that “several” U.S.
airlines are now subscribing. Competitor AvTech has a simi-
lar subscription-based wind update service that Southwest
Airlines is using for its entire fleet for descents.
Meserole says there is other research underway that will
further optimize an FMS with real-time weather data, yield-
ing “ways of meeting time objectives without taking the air-
craft out of economy mode.”
Boeing is also proposing to test a low-cost method to in-
crease capacity at airports that host a mix of light, medium
and heavy aircraft landing on the same runway. The company
has a goal of beginning a trial on Runway 4R/22L at Newark
Liberty International Airport (EWR) this year.
Called “Descent Angle to Displaced Thresholds,” the tech-
nology includes creating a second threshold farther down a
runway that will allow aircraft the size of a Boeing 737 or an
Airbus A320 to follow heavy air-
craft like the Boeing 777 or Airbus
A330 at a distance as close as 3
nm, rather than the usual 5 nm, an
in-trail distance designed to mini-
mize wake-turbulence encounters.
The extended touchdown
point for the lighter aircraft
provides a higher glideslope
that keeps the aircraft above
the wake of the heavy aircraft
ahead. Additional margin could
be gained from using a steeper
glideslope for the approach.
“This is a way to make the wake
issue on a single runway go away
completely,” says Meserole, add-
ing that the process would work
in visual as well as instrument
flight rules (IFR).
Meserole credits German air
navigation service provider DFS,
the German aerospace center
DLR, as well as Frankfurt Airport
Service (Fraport) for completing
the original work on the concept in the mid-2000s. At the
Frankfurt airport, the team tested a displaced threshold on
one of the two parallel runways (25R and 25L) to decrease
separation between heavy aircraft on one runway and lighter
aircraft on the other.
The system was meant to allow for independent operations
of the two runways, despite a lateral separation of only 1,700
ft. between the two. The airport renumbered 25L to 26L and
moved the threshold 4,900 ft. inward, making the glidepath
300 ft. higher compared to the parallel runway, thereby avoid-
ing the path of the vortices. A new lighting and instrument
landing system was also installed. Meserole says the test was
successful, but was discontinued due to complications that
occurred when the tower had to change landing direction due
to wind shifts. Frankfurt later built a third parallel runway for
single-aisle aircraft to solve its capacity issues. Germany also
studied single-runway displaced threshold operations with
a controller- and pilot-in-the-loop simulation, showing that
the concept would work, says Meserole. “What they didn’t do
was investigate all the safety issues,” he notes. “That’s what
we’re trying to do.”
One of those safety studies will address the minimum run-
way length and maximum glideslope needed. Meserole says
EWR’s Runway 4R/22L, with 10,000 ft. available, could be “a
little marginal,” but that analysis has not yet been carried out.
Another safety issue involves setting the glideslope angle for
the lighter aircraft. Meserole says the angle would not likely
be higher than the 3.5 deg. path the Boeing 737 can already fly.
Newark is an ideal location in one respect—it has a Honey-
well-built SmartPath GPS landing system for which multiple
glideslopes can be set up to the same runway. United Airlines
is the initial user of that system and has more than 100 737s
and 787s equipped to use the landing aids.
Meserole says Boeing has been discussing the project with
the FAA since last year. “The next step is to define a state-
ment of work for the study phase,” he says, adding that the
goal would be to develop a public-private partnership for the
project. cAviationWeek.com/awst AVIATION WEEK & SPACE TECHNOLOGY/JANUARY 15-FEBRUARY 1, 2015 69
The NASA-developed Cockpit
Situation Display provides a
3-D graphic of current and
future weather, trafc and
obstacles along an aircraft’s
route.KLM