TCAS Interrogation for Aircraft Merging Spacing Data
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Solution Overview
Problem
Current merging and spacing designs based on Automatic Dependent Surveillance—Broadcast (ADS-B) data are performance limited due to bandwidth restrictions, which prevent the inclusion of additional aircraft parameters, leading to increased message congestion and readability issues when multiple aircraft transmit simultaneously.
Innovation Solution
Integrating Mode S Elementary Surveillance (ELS)/Enhanced Surveillance (EHS) technology with Traffic Collision and Avoidance System (TCAS) to selectively interrogate lead aircraft for supplemental data, reducing frequency congestion by only transmitting requested data when needed, and combining it with ADS-B data for improved calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If additional aircraft parameters are added to the ADS-B data set, then merging and spacing performance is improved, but bandwidth restriction is violated and message congestion increases
Solution Approach 1:
The system combines data from multiple sources (ADS-B broadcasts and TCAS interrogations) into a unified data set for merging and spacing operations. This allows the following aircraft to access both broadcast and interrogated parameters through a single integrated application, improving performance without increasing the number of ADS-B messages
Solution Approach 2:
The TCAS system performs multiple functions: it provides collision avoidance alerts and simultaneously serves as a data collection mechanism for merging and spacing operations. By interrogating the lead aircraft's transponder, the system obtains comprehensive aircraft parameters that would otherwise require separate dedicated data links
2Productivity
If additional aircraft parameters are added to the ADS-B data set, then merging and spacing performance is improved, but the probability of simultaneous transmissions increases
Solution Approach 1:
Instead of continuous broadcasting of all parameters, the system uses periodic TCAS interrogations at specific decision points (merge decision, spacing decision) to obtain required data. This reduces the frequency of transmissions compared to continuous ADS-B broadcasting of expanded parameter sets
Solution Approach 2:
The system extracts only the specific aircraft parameters needed for merging and spacing decisions from the lead aircraft through targeted TCAS interrogations, rather than requiring the lead aircraft to broadcast all possible parameters continuously. This selective extraction reduces transmission load while maintaining data quality
Data Source
AI summary
Systems and methods are delineated that may provide for a system for use in a merging and spacing application for an aircraft. An exemplary system may comprise a TCAS and a processor for executing the merging and spacing application using ADS-B data and data received by the aircraft in response to an interrogation of another aircraft from the TCAS. In a disclosed embodiment, a lead aircraft responds to the TCAS interrogation from a following aircraft to provide EHS heading and/or speed of the lead aircraft to the following aircraft, which uses the received EHS data as well as ADS-B data to determine merging and spacing control parameters for the following aircraft.