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 System1 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.