Trajectory-Based Operations (TBO) - Joint Planning and ...
Trajectory-Based Operations (TBO) - Joint Planning and ...
Trajectory-Based Operations (TBO) - Joint Planning and ...
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<strong>Trajectory</strong>-<strong>Based</strong> <strong>Operations</strong> (<strong>TBO</strong>)<br />
Study Team Report<br />
overcast <strong>and</strong> gradually decreasing to 1,000 feet with chance of heavy snow showers,<br />
gusts to 40 knots <strong>and</strong> icing in clouds <strong>and</strong> snow showers.<br />
12.6 Arrival/Approach <strong>and</strong> L<strong>and</strong>ing Assumptions<br />
For parallel runway operations:<br />
• While there are no current plans at IAD, many hub airports (including IAD) may have new<br />
parallel runways, spaced as close as 750 feet from an existing runway, by 2025. In order to<br />
show how closely spaced parallel runway operations work in concert with airborne merging<br />
<strong>and</strong> spacing <strong>and</strong> time-based spacing, a new parallel runway has been created for the IAD arrival<br />
scenario that is 750 feet from an existing runway.<br />
• The DTW to IAD scenario is based on one of several proposed concepts for closely spaced<br />
parallel runway operations. The concept is designed to accommodate dependent pairing of<br />
aircraft with dissimilar final approach speeds. The conformance zone is defined only by wake<br />
avoidance. The aircraft with the faster Final Approach Speed (FAS) is initially positioned<br />
behind the aircraft with the slower final approach speed. After the coupling point when the<br />
aircraft slow to their respective final approach speeds, before the SAP, the trailing faster<br />
aircraft may safely overtake the slower lead aircraft <strong>and</strong> move some distance ahead before<br />
l<strong>and</strong>ing, still staying within the conformance zone. Future research will determine whether<br />
passing can be safely conducted at runways spaced laterally as close as 750 feet. If passing is<br />
not supported, then aircraft pairs must have much closer final approach speeds.<br />
• Similar to dynamic wake spacing, the size of the conformance zone varies dynamically with<br />
environmental conditions, especially crosswind speed <strong>and</strong> direction.<br />
• The parallel runway breakout maneuver is not a 4DT since it does not specify the aircraft’s<br />
position as a function of time, but rather relative to the point at which the breakout is initiated.<br />
When an aircraft conducts a breakout maneuver, it has an open trajectory until closed by the<br />
ANSP.<br />
• An aircraft is not allowed to overtake another aircraft in the same stream/STAR unless they are<br />
traveling at different altitudes.<br />
• Much of the information exchange between the flight deck <strong>and</strong> ANSP will be via data link. For<br />
example, rather than today’s Automatic Terminal Information Service (ATIS) messaging, the<br />
aircraft will receive a data link message with current weather <strong>and</strong> airport configuration<br />
information.<br />
• By 2025, STARs supporting OPDs will be created for all arrivals for high-density airports.<br />
These OPD STARs will have a defined 2D route, but will have waypoint altitude crossing<br />
restrictions defined as a range of altitudes, defining a vertical volume designed to accommodate<br />
a variety of aircraft with different weights <strong>and</strong> performance characteristics.<br />
• In high-density traffic, an arrival stream will contain a string of aircraft conducting airborne<br />
merging <strong>and</strong> spacing to a runway. A complicating factor in spacing is the need to accommodate<br />
stabilized approaches for aircraft with different final approach speeds (i.e., the aircraft must<br />
slow to its appropriate approach speed <strong>and</strong> be configured for l<strong>and</strong>ing before descending below<br />
1000 ft AGL). The spacing 4DTs must include a buffer to accommodate differences in<br />
approach speeds because a faster aircraft will be gaining on the aircraft ahead, while a slower<br />
aircraft will be falling behind the aircraft ahead during the last three nm of the approach.<br />
<strong>Joint</strong> <strong>Planning</strong> <strong>and</strong> Development Office<br />
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