Tutorial
Low Visibility Landing and Surface Operations (LVLASO)
Hazardous runway incursions have increased by more than 50 percent over the last several years and
five fatal airport surface accidents have occurred since 1990. In 2000, reports of surface incidents averaged more
than one a day. Reduced visibility was given as a contributing factor in many of these accidents and incidents.
To operate safely on the airport surface during poor weather at rates equal (or better) to those in clear weather, aircrews and controllers need supplemental information about the airport and relevant traffic. This information should "fill the gaps" created by the visual cues that may be missing during poor weather conditions.
The aircraft's flight crew requires three types of information to control the movement of the aircraft while
avoiding an accident/incident on the airport surface. These include the following:
· continuous awareness of their position on the ground
· continuous awareness of traffic or obstacles that may impede their movement to their destination (whether
moving to a gate or to a takeoff runway)
· an understanding of the route their aircraft needs to follow from its current position to its directed
destination
Ground controllers also need similar information for all vehicles (ground transport and taxiing aircraft) moving on the surface.
NASA's Aviation Systems Capacity Program addresses these issues through the Low Visibility Landing and Surface Operations (LVLASO) research. LVLASO has shown, through simulation and flight test activities, how new technologies can be used to reduce the uncertainties in poor weather conditions. It does this by providing controllers and pilots with greater visual and communication aids. LVLASO has been simulated and tested at NASA Langley Research Center, Atlanta's Hartsfield Airport, and Dallas/Ft. Worth (DFW) Airport.
The LVLASO research tested systems for both airborne and ground-based traffic. The following airborne systems
were tested:
· Electronic moving map using a liquid-crystal display that allows the pilot to view the aircraft's position
· Pilot Head-Up Display which visually displays to the pilot the directed procedure of roll-out, turn-off,
and taxiing
· Differential Global Positioning System (DGPS) as the position sensor for cockpit crew that more accurately
pinpoints the aircraft's position
· Data links that consistently transmit the most recent data to/from the airborne and ground systems
The following ground-based systems were tested:
· Surface surveillance radar to more accurately provide traffic position reports all around the airfield
· Airport Traffic Identification System traffic position
reports with identification that helps the controllers and pilots recognize not only their position, but the position
of other vehicles
· Surveillance data fusion system that brings together in a meaningful visual display all sources of position
data to both a controller's display and a pilot's cockpit display
· Computer interface that supports a direct controller-to-pilot datalink
· Data communications in parallel with the normal voice communications, so as the pilot hears directions
from the controller, additional data to help give the pilot a more complete picture is also displayed in the cockpit.
The LVLASO technology has the potential to significantly increase the safety and efficiency of aircraft movements
on the airport surface by giving the following information:
· Supplemental guidance cues and increased awareness of the current situation
· More accurate, low visibility surface navigation that will decrease runway incursions
· Increased visual and verbal communications to reduce navigation errors, runway occupancy time, aircraft
taxi time and controller/pilot miscommunications
· Increased visual cues that will improve braking efficiency and increase the capability of safe vehicle
operations regardless of the visibility on the surface
