Honeywell is debunking fears about bogus CPDLC messages, sparked by an event last month involving a Gulfstream G550 flying in Shanwick Ocean Control airspace over the northeastern Atlantic Ocean. According to a Flight Service Bureau blog post, the G550 crew received a “DESCEND AT MAXIMUM” message via CPDLC, but when they checked on voice with ATC, it hadn’t come from them.
But Honeywell said the “↓ DESCEND AT * MAXIMUM” message was actually a downlink message to ATC from the FMS (as indicated by the down arrow), not an uplink from ATC. “During our analysis of the reported incident, we found that the blog post had some incorrect information, because it was not an uplinked error message, but rather a downlinked error message." While the blog post correctly states that it was a single event and that no spoofing or hack occurred, the root cause has not yet been determined, Honeywell told AIN. The G550 is equipped with a Honeywell FMS, among other avionics from the Phoenix-based company. Honeywell said. “We have never seen and have not received other reports of this issue. We are currently still investigating the root cause but believe this is an isolated incident that will not affect other systems.”
“Additionally, the next message, ‘↑ DOWNLINK ERROR’ is an uplink from ATC that was sent indicating there was something incorrect with that specific downlink.Honeywell said this uplink from ATC, which indicated that Shanwick rejected the downlink, “demonstrates the end-to-end communication protocol is working per design.”
Further, “Honeywell reviewed the message logs obtained from the service provider and confirmed that at the same time the ‘↓ DESCEND AT * MAXIMUM’ message was displayed on the ‘ATC LOG’ page, a downlink was observed in the logs, but the data was corrupt (unable to decode into any expected data format),” the company told AIN.
“Downlink messages are generated by the FMS and stored in the ATC LOG. This one downlink was erroneously encoded by the FMS as corrupt data, and the ATC LOG page display decoded the corrupt data as ‘↓ DESCEND AT * MAXIMUM.’ The presence of the star in the message indicates the FMS decoded to the ‘↓ DESCEND AT * MAXIMUM’ message but could not decode a valid vertical rate—for example, it should display as DESCEND AT 1000 FT/MIN MAXIMUM—so it displayed a star instead.”
Honeywell said it is still determining the root cause, “but we can confirm that message was generated by the FMS and that this was not the result of spoofing or hack.”
Honeywell is debunking fears about bogus CPDLC messages, sparked by a recent n event last month involving a Gulfstream G550 flying in Shanwick Ocean Control airspace. According to a Flight Service Bureau blog post, the G550 crew received a “DESCEND AT MAXIMUM” message via CPDLC, but when they checked on voice with ATC, it hadn’t come from them.
But Honeywell said the “↓ DESCEND AT * MAXIMUM” message was actually a downlink message to ATC from the FMS (as indicated by the down arrow), not an uplink from ATC. “During our analysis of the reported incident, we found that the blog post had some incorrect information, because it was not an uplinked error message, but rather a downlinked error message." While the blog post correctly states that it was a single event and that no spoofing or hack occurred, the root cause has not yet been determined, Honeywell told AIN. The G550 is equipped with a Honeywell FMS, among other avionics from the Phoenix-based company. Honeywell said. “We have never seen and have not received other reports of this issue. We are currently still investigating the root cause but believe this is an isolated incident that will not affect other systems.”
“Additionally, the next message, ‘↑ DOWNLINK ERROR’ is an uplink from ATC that was sent indicating there was something incorrect with that specific downlink. Honeywell said this uplink from ATC, which indicated that Shanwick rejected the downlink, “demonstrates the end-to-end communication protocol is working per design.”
Further, “Honeywell reviewed the message logs obtained from the service provider and confirmed that at the same time the ‘↓ DESCEND AT * MAXIMUM’ message was displayed on the ‘ATC LOG’ page, a downlink was observed in the logs, but the data was corrupt (unable to decode into any expected data format),” the company told AIN.
“Downlink messages are generated by the FMS and stored in the ATC LOG. This one downlink was erroneously encoded by the FMS as corrupt data, and the ATC LOG page display decoded the corrupt data as ‘↓ DESCEND AT * MAXIMUM.’ The presence of the star in the message indicates the FMS decoded to the ‘↓ DESCEND AT * MAXIMUM’ message but could not decode a valid vertical rate—for example, it should display as DESCEND AT 1000 FT/MIN MAXIMUM—so it displayed a star instead.”
Honeywell said it is still determining the root cause, “but we can confirm that message was generated by the FMS and that this was not the result of spoofing or hack.”