Pair-wise Trajectory Management (PTM) is a concept that utilizes airborne and ground-based capabilities to enable airborne spacing operations in oceanic regions. The goal of PTM is to use enhanced surveillance, along with airborne tools, to manage the spacing between aircraft. Due to the precision of Automatic Dependent Surveillance- Broadcast (ADS-B) information, the PTM minimum spacing distance will be less than distances currently required of an air traffic controller. Reduced minimum distance will increase the capacity of aircraft operations at a given altitude or volume of airspace, thereby increasing time on desired trajectory and overall flight efficiency.
PTM is designed to allow a flight crew to resolve a specific traffic conflict (or conflicts), identified by the controller, while maintaining their desired altitude. The controller issues a pair-specific PTM clearance to a flight crew authorized to conduct PTM operations in order to resolve a conflict for the pair of aircraft (i.e., the PTM aircraft and a designated target aircraft). This clearance requires the flight crew of the PTM aircraft to use their ADS-B-enabled onboard equipment to manage their spacing relative to the target aircraft to ensure spacing distances that are no closer than the PTM minimum distance. When the controller determines that PTM is no longer required, the controller issues a clearance to terminate the PTM operation.
Flight crews authorized to conduct PTM operations will require the use of a PTM Human Machine Interface (HMI). One possible implementation involves the PTM HMI operating independently of other flight guidance and navigation displays. A retrofit implementation of this type has been investigated at NASA Langley. Future implementations could be fully integrated, for example, with the Primary Flight Display (PFD), Navigation Display (ND), and Multifunction Control Display Unit (MCDU).
The retrofit implementation will require flight crew members to interact with a PTM software application through the use of side-mounted auxiliary displays equipped with touchscreen interfaces and, during PTM operations, a 3" × 3" PTM guidance display will be located in the flight crew’s forward field-of-view. Information elements associated with the PTM software application that flight crews will interact with using the side-mounted display and information elements shown on the forward field-of-view PTM guidance display have been developed at NASA Langley.
The PTM HMI provides the means for a flight crew to conduct a PTM operation. The display also provides situation awareness of proximate aircraft and speed guidance needed to maintain separation for controller-assigned aircraft. The PTM HMI was developed using an iterative design process that incorporated an operational task analysis, human factors best practices, feedback from the aviation community, and industry standards.