For large airports with high density incoming traffic during peak periods there was a need for a tool to assign flights to runways in an efficient sequence. This tool was to complement a capability in the en route center that assigns aircraft to a spot in the sequence of arriving flights and an assigned time of arrival over an inbound fix in the center’s airspace near the TRACON boundary. Once the aircraft made the transition to the TRACON, pFAST would provide the terminal controller with recommendations to make the most efficient use of airspace and runway resources by making a runway assignment and sequence number recommendation. pFAST was developed during the 1990s and fielded in 2001.
The pFAST tool was part of a larger suite of tools developed by NASA in the Center TRACON Automation System (CTAS) program. There was extensive simulation and prototyping activity including substantial human factors expertise. Prototypes of the tool were installed and used on a limited basis at two TRACONs to get user input. The initial fielding of the tool went to six sites.
There is no evidence that Human Performance requirements at the system or functional level were ever generated prior to the onset of full scale system development. Since there was general acknowledgement that the arrival stream of aircraft at a major airport such as Dallas-Fort Worth could be more efficient with the application of the proper algorithms, the system was introduced gradually as part of the evolution of technology. When the appropriate Technology Readiness Level was reached there was an expectation that the technology would be adopted and adapted for field use to enhance air traffic control efficiency. However, numerous inputs regarding detail design requirements for the display were made by human factors researchers.
As part of the CTAS program there was a long history of laboratory development including simulations that progressed to high fidelity full mission capability. The technology made a partial transition to the field as part of risk reduction by being introduced on auxiliary displays for controllers to use initially for familiarization and informal evaluation. Later, the auxiliary displays were used for situation awareness at controller workstations to determine if the recommended runway assignments and sequence numbers were reasonable and valid as judged by local subject matter experts (SME). On-site researchers recorded SME comments and fed them back to programmers and algorithm engineers to enhance the quality and acceptability of the recommended solutions. Eventually, the tool was at least partially installed at six major TRACONs. At the request of the controller’s union, the tool implementation was halted.
Human factors researchers participated heavily in automation development. They were involved in the early stages of development, laboratory simulations, and field trials. Extensive use was made of SMEs, including union representatives, during all stages of development including simulations at various levels of fidelity, prototyping, and field trials in “shadow mode” where the tool was available only for situation awareness.
Tool development and implementation was halted in a contentious environment. It was clear that this was a case of premature introduction of automation in the air traffic control domain. While the en route center portion of the automation tool (Traffic Management Advisor) was generally well received and functioned as advertised, pFAST was not ready for use in the Terminal domain. The experience was viewed as negative.
The introduction of this automation was definitely not a success. A lessons learned report was generated, but not widely circulated. Key elements of the report cite the following concerns as contributors to the demise of this piece of air traffic control automation:
Additional citations from the “lessons learned” report:
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