Flight Deck Procedural Guidelines for Datalink Trajectory Negotiations

Abstract

This paper presents an evaluation of three different flight deck procedures for their compatibility with a Trajectory-Based Operations Concept. Particular emphasis is placed on the interoperability of trajectory-based automation concepts and technologies with modern Flight Management Systems and datalink communication to enable negotiation between air and ground. A two-way datalink connection between the trajectory-based automation resident in the Center/TRACON Automation System and the Future Air Navigation System-1 integrated Flight Management System/datalink in NASA Ames' B747-400 Level D simulator has been established. Simulation experiments investigated the use of datalink messages to communicate strategic trajectories.A strategic trajectory is defined as an aircraft deviation needed to solve a conflict or otherwise modify a flight plan route and then merge the aircraft back to its nominal preferred trajectory using a single continuous trajectory clearance. A preliminary pilot-in-the-loop simulation evaluated two candidate procedures using a variety of horizontal and vertical trajectory clearances and found each to be feasible for basic datalink trajectory exchange. The procedure most preferred by the flight crews was adapted to enable trajectory negotiation and a second piloted simulation was conducted to measure important parameters that affect safety and efficiency. This simulation established that limited information exchange during trajectory negotiation between flight deck and ground based automation systems is feasible using current aircraft equipment and modified procedures, but that a number of factors relating to flight deck procedures are important to consider when constructing datalink clearances. Guidelines for designing flight deck-compatible clearances are presented along with the effect of several conditions on the crew's message response time and the extent to which crews initiated negotiations. Among other results it was found that response times are generally shorter for vertical trajectories than horizontal, that prescribed minimum climb rates are difficult for crews to follow, and that basic negotiation using text-based messages requires little extra time than non-negotiated clearances.

Effect of conflict resolution maneuver execution delay on losses of separation

“…These values cover roughly 95% of the response times observed in the Mueller study [4]. The use of four additional execution delay times was due to the wide range of response times observed.…”

“…For horizontal maneuvers, for example, this delay is on the order of two minutes [4], which is a little more than twice the nominal time observed in that same reference. Using an expected delay of two minutes means a conflict detected with eight minutes must use a resolution that only has six minutes available for the aircraft actually to maneuver, while planning for the nominal execution delay of about one minute allows for seven minutes of maneuvering time.…”

“…ThIS IS the delay between when a conflict resolution maneuver is sent to an aircraft via data link and when the aircraft actually begins flying this maneuver. For the purposes of this study, the baseline resolutions used a nominal delay of 56 seconds for horizontal maneuvers and 39 seconds for vertical ones based on pilot response data from the Mueller and Lozito study [4].…”

“…Consiglio et al [2] examined the effects delayed pilot responses to conflict alerts in an airborne self-separation system, and McNally et al [3] included uncertainties in the execution of resolution maneuvers as part of an overall Trajectory Based Operations study. There has also been a human-in-the-Ioop study measuring pilot response times to data linked conflict resolution messages using a data link equipped aircraft [4]. These studies do not explicitly explore the effects of maneuver execution delay, however.…”

“…As different procedures are needed for implementing different maneuver types, different nominal delays for horizontal and vertical maneuvers were used. The values of these delays were taken from the previously mentioned reference [4].…”