Southwest Airlines is in the process of a three-phase avionics retrofit program on its Boeing 737 NG fleet, which is slated to number 625 by the end of 2016 and includes a mix of 737-700 and -800s. The first phase involves making the aircraft compliant with requirements for Automatic Dependent Surveillance-Broadcast (ADS-B) “Out.”
“As the aircraft have been delivered over the years, they have come with different degrees of infrastructure capable of supporting ADS-B Out,” says Kent Horton, the carrier’s director of aircraft engineering. The project involves the installation of new wiring, ILS/GPS multimode receivers and new RTCA-DO-260B transponders from Honeywell, which will have those components available in mid-2017. The wiring will be done as part of a major airframe inspection, while the component installation will be performed during an overnight check.
The project’s second phase is replacement of the digital flight-data acquisition unit (DFDAU) to achieve a greater degree of aircraft health monitoring. “The new unit, a Teledyne product, will have greater memory and processing capabilities and will make the aircraft more e-enabled,” Horton says, adding that the installations are slated for completion in November.
The third phase will replace the 737 NG’s communications management unit (CMU) with a Honeywell system providing greater memory and processing capability. Completion is scheduled for 2018.
Asked if commonality with the 737 MAX, which Southwest will start operating next year, was among the upgrade incentives, Horton says: “The systems will not be absolutely identical, but we will have comparative functionality.”