Table 2. Target State Report Elements for Figure 3

TS Report Element #  Contents  Example Values 
Horizontal  4a  Horizontal Data Available and Horizontal Target Source Indicator  MCP Selected Heading 
Short  4b  Target Heading or Track Angle  090 deg 
Term  4c  Target Heading/Track Indicator  Target Heading 
Intent  4e  Horizontal Mode Indicator  Capturing/ Maintaining 
Vertical  5a  Vertical Data Available and Vertical Target Source Indicator  MCP Selected Altitude 
Short  5b  Target Altitude  8,000 ft 
Term  5c  Target Altitude Type  MSL 
Intent  5d  Target Altitude Capability  Full Capability 
5e  Vertical Mode Indicator  Acquiring 

In another example, the aircraft in Figure 4 is turning to join a 040 course (track) to the ABC waypoint. It is holding its current altitude (15,000 ft). TS report values are provided in Table 3. The target source indicators show that the target track comes from the FMS, while the target altitude is the MCP selected altitude. Horizontal and vertical target states are available and considered reliable. As shown by the mode indicators, the aircraft is acquiring the horizontal target and maintaining the vertical target. Mode indicators show that horizontal and vertical target information is available.
Target Altitude (15,000 ft)
ABC DEF

GHI

Figure 4. Intercept Course to FMS Flight Plan at Constant Altitude Table 3. Target State Report Elements for Figure 4
TS Report Element #  Contents  Example Values 
Horizontal  4a  Horizontal Data Available and Horizontal Target Source Indicator  FMS/RNAV 
Short  4b  Target Heading or Track Angle  040 deg 
Term Intent  4c  Target Heading/Track Indicator  Target Track Angle 
4e  Horizontal Mode Indicator  Acquiring 
Vertical Short Term Intent  5a  Vertical Data Available and Vertical Target Source Indicator  MCP Selected Altitude 
5b  Target Altitude  15,000 ft 
5c  Target Altitude Type  MSL 
5d  Target Altitude Capability  Full Capability 
5e  Vertical Mode Indicator  Capturing/ Maintaining 

5 Trajectory Change Point (TCP) Definition
Further investigation into the many types of TCPs that can occur along an operational trajectory has led to a revised TCP definition for DO-242A. The new definition accommodates TCPs that do not occur at a known 3D position in space. Many flight segment changes occur when certain trajectory conditions are met, rather than at defined points in space. For example, an aircraft may be climbing in a constant vertical speed mode towards a target altitude (Figure 3). In this case, the condition for changing trajectory is based on capturing the target altitude and not on arrival at a defined point. The predicted location accuracy of these TC types may depend on unknown wind conditions and changing aircraft performance. An analogous lateral situation may occur when an aircraft flies at constant heading to intercept a flight plan route (see Figure 8). In this case, the first TCP occurs when intercepting the track to the next FMS/RNAV waypoint. The intercept location is also dependent on wind parameters that may not be accurately known.
The following TCP definition has been adopted to accommodate prediction uncertainties: “A trajectory change point (TCP) is a point where an anticipated change in the aircraft’s velocity vector will cause an intended change in trajectory.” The change in trajectory may be either a change in path or a change in speed. Examples of TCPs under this definition include 2-D routing changes, the start and end points of a specified turn transition, FMS predicted Top of Climb and Top of Descent points, and target altitudes such as MCP selected altitude when currently in climb or descent transitions. A full list of TC types included in DO-242A is provided in Section 8. Future revisions may add additional TC types that meet this definition.
　
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