Flight testing of Boeing’s 787 “EcoDemonstrator” ended on Wednesday following a month of trials involving 25 technologies designed to increase efficiency and reduce noise and emissions. Using 787 Dreamliner flight-test article ZA004, Boeing evaluated advances in software and connectivity, improvements in aerodynamics and flight controls, remote sensors to reduce wiring and “icephobic” wing coatings to mitigate ice accumulation.

On the day of the final flight, Boeing Commercial Airplanes director of environmental performance Jeanne Yu and BCA director of environmental strategy and integration Julie Felgar briefed reporters on the results of the most recent flight trials, which began on November 17. Yu highlighted one series of tests, associated with GLS Cat III, as particularly significant because it generated the final set of data for the procedure’s eventual integration into commercial airspace using a ground based augmentation system (GBAS). “The Cat III allows for a higher glidepath for reduced community noise,” she said. “It also, because it’s Cat III, provides landing approach capability down to fifty feet. It really provides greater airport access in all kinds of weather and in mountainous terrain.”

Testing of more avionics technology involved an element of the NextGen navigation system called ADS-B, initial installation of which the U.S. will require in 2020. Specifically, the Boeing 787 tested ADS-B In, where satellite-enabled transmissions from another airplane using ADS-B Out allow for the precise tracking of its position. Using ADS-B In/Out data, NASA’s ASTAR (Airborne Spacing for Terminal Arrival Routes) algorithm gives pilots specific speed information and guidance to allow for more precise spacing on approach, thereby minimizing flight path deviations and allowing for more efficient use of existing airspace.  In effect, the ASTAR system tells the pilot how fast to fly to maintain a precise distance from the airplane he or she is following, explained Yu.

“We actually flew five trials of ASTAR...and really had good success,” said Yu. “We were trying to apply two-minute spacing intervals, and sometimes it was spot-on, sometimes it was a tenth of a second off, but always within a few seconds of the targeted two-minute spacing of those airplanes.”

The tests included the first-ever flights powered in part by so-called green diesel, a type of sustainable biofuel derived, in this case, from used cooking oil. On December 2 Boeing flew the 787 EcoDemonstrator on a 15-percent green diesel blend in the 787’s left engine. The following day it flew the same blend in both engines, reported Felgar.

Researchers expect the data will support plans to raise the biofuel-to-Jet-A blend ratio from 15 percent to 50 percent by the middle of next year. Boeing “is considering” testing green diesel again when it launches its next round of EcoDemonstrator flights using a 757 next year in partnership with TUI Travel and NASA, said Felgar.

Already used in ground transportation, green diesel gets produced at a rate of more than 800 million gallons each year. Once Boeing and its partners complete the ASTM approval process and airlines become end users, the total only stands to increase. “There are a number of airlines that are actively working with us, looking at the green diesel and identifying how they will be able to use it once the fuel gets approved,” said Felgar.