This webinar took place over Zoom on Tuesday, December 17th, 2024, at 1PM Pacific Time / 4PM Eastern Time.

Our guests were Andrea Sparko and Dr. Divya Chandra from the Volpe National Transportation Systems Center. They presented a study on flight deck human factors considerations for Performance Based Navigation (PBN) departure procedures (DPs). This work focused on issues relevant to the Multiple Airport Route Separation (MARS) concept, a proposed air traffic control initiative by the FAA aimed at improving traffic flow in busy terminal areas with multiple airports.

Andrea began by explaining the significance of PBN, which relies on space-based waypoints for more precise routes compared to conventional navigation that depends on ground-based aids. In previous work, the authors already reviewed human factors issues on PBN charts ex. more precise routes and constraints, with more notes and information to process and non-standard chart layouts. She emphasized that PBN, including RNAV and RNP, is a key component of the FAA’s NextGen system, designed to enhance the efficiency and safety of air traffic management.

PBN instrument flight procedure is central to a proposed air traffic control concept called Multiple airport route separation (MARS). Plans are to use MARS to deconflict terminal-area traffic between adjacent airports, for example an ILS 4 approach procedure to LGA intersecting with the ILS 13L approach to JFK. MARS can deconflict these two procedures by using a PBN approach procedure and having the JFK 13L approach being parallel to the LGA ILS 4 procedure by as little as 3 NM from one to another. This raises concerns on potential deviations from the procedure and the crew perception of risk with being closer to surrounding traffic.

The primary goal of this study is to understand flight crew perspectives on PBN departure procedures and their relevance to MARS. The research involved discussions with 4 technical pilots, analysis of a curated set of 20 records from NASA’s Aviation Safety Reporting System (ASRS), and discussions with 9 airline pilots. Andrea highlighted that the study aimed to fill several research gaps, including the need for updated data on flight crew issues with PBN DPs, factors contributing to flight path deviations, and flight crew perceptions of traffic during MARS operations.

One of the key findings from discussions with technical pilots was that PBN departures now have more vertical constraints than before, increasing pilot workload. Andrea explained that with PBN procedures “pilots now routinely use the flight management system to fly departure procedures, which means they require a deeper understanding of their automated systems.” This shift necessitates enhanced training and knowledge for pilots to manage these complex procedures effectively. One thing that did not change with PBN departure procedures is that ATC amendments continue to pose a risk of flight path deviations. This happens when ATC puts additional vertical and speed constraints to the published procedure.

The analysis of ASRS records revealed that unintentional deviations were often triggered by task management issues and ATC amendments. Andrea pointed out that departure tasks are highly time-sensitive, with pilots managing multiple aspects simultaneously, including airplane configuration, flight path, automation, and communication with ATC. “Disruptions and distractions can quickly lead to task saturation and operational pressures,” she said.

In discussions with 9 airline pilots, the study explored how they perceived traffic during MARS operations as it can be closer than they are used to. Using two simulated traffic scenarios on a Boeing 737 navigation display with TCAS overlay, pilots assessed traffic threats and discussed scenarios where they might deviate from a departure route. In scenario 1, there were two departing aircraft, one from JFK 31L with fast climb rate and another traffic leaving from LGA 13 with slow climb rate, such that the two aircraft would be within 3 NM and 1000 ft from each other. The findings indicated that pilots’ threat perception of the traffic evolved as it came closer to ownship (see figure below). Participants reported they were planning to take action to evade the LGA aircraft as it came close to their position. Andrea also noted that “several pilots said they would ask ATC about the traffic if they hadn’t yet heard from ATC,” indicating the need for clear communication and coordination between pilots and air traffic controllers.

Airline pilots also listed sources for unintentional deviations in departure procedures, all related to interaction with automated systems: error in FMS programming after receiving an ATC amendment, incorrect selection of lateral or vertical navigation mode, autopilot not engaged. Sources for intentional deviations were fewer, mostly in response to external factors such as weather, traffic and system failure.

The study also examined the implications of MARS for air traffic control and flight operations. Andrea emphasized that ATC procedures might need to be designed to handle disruptions to MARS operations, as deviations do occur. She suggested that instrument flight procedures should be easy to fly to minimize the risk of deviations, and air traffic controllers should be prepared for pilots to ask about traffic. “We want to avoid the worst-case scenario where there’s a deviation in the area of reduced separation,” she stressed.

One of the audience questions addressed the implications of MARS for aircraft manufacturers and designers of aircraft systems. Divya responded by highlighting the importance of making flight management systems as easy to use as possible, as they are all different between manufacturers and can be slow to update. “Reviewing and modifying programmed instructions for your flight management system is a huge component of workload and potential for error,” she explained, urging manufacturers to consider the ease of use in their designs.

Another question from the audience inquired about the potential need for pilot training on MARS. Andrea acknowledged that this is still an open consideration, especially on the perception of surrounding traffic. Divya also emphasized the importance of understanding how much education pilots need about MARS and what specific information they require.

In conclusion, Divya highlighted that MARS was initially an ATC initiative. The team at Volpe was glad to join this effort to offer the pilot’s perspective to ensure a smoother integration of MARS in the airspace.

And we are glad the Andra and Divya could have shared their results with us!