Air carrier flight crew reported loss of GPS during cruise after initial GPS jamming event on their flight from Madrid to Hong Kong. Crew continued and landed with degraded navigation capabilities.
Synopsis
Air carrier flight crew reported loss of GPS during cruise after initial GPS jamming event on their flight from Madrid to Hong Kong. Crew continued and landed with degraded navigation capabilities.
Narrative
During our flight from Madrid (LEMD) to Hong Kong (VHHH); we experienced GPS jamming. At the onset of the jamming; I was the pilot monitoring; while my first officer was the pilot flying. I referenced the updated non-normal checklist for GPS jamming and elected to disable the GPS receiver until we cleared the area typically affected by GPS interference. I informed ATC of the GPS loss.After completing my rest period; I returned to the flight deck approximately 90 minutes prior to landing. By this time; we were in Chinese airspace; well beyond the region where GPS jamming typically occurs. However; I was surprised to find the aircraft still operating in DME-DME updating mode. I confirmed that the GPS receiver had been re-enabled; but GPS functionality was still unavailable.The pilot flying was preparing for an RNAV arrival requiring RNAV 1 performance; as Hong Kong was advertising only the RNAV 07C approach procedure. I reminded the crew that; without GPS; we were not authorized to conduct RNAV 1 procedures. I notified Chinese ATC that we lacked GPS and were unable to perform RNAV arrival or approach procedures; which they acknowledged. Dispatch contacted Hong Kong on our behalf and relayed back to us that we would receive vectors for the ILS 07C approach.
Second reporter narrative
During our flight from Madrid (LEMD) to Hong Kong (VHHH); we experienced GPS jamming which is not uncommon for the route of flight; we had anticipated it. During the initial start of the jamming I was in rest; but it was relayed to me that the non-normal checklist was accomplished; GPS updating was turned off and ATC was notified. As the flight progressed and we left the area typically associated with GPS jamming; GPS was turned back on and it became apparent that GPS updating was not working. As we got closer to VHHH we saw that that VHHH was utilizing RNAV arrivals and approaches; we contacted company to forward a message to VHHH about our degraded navigational capabilities; we also reminded ATC. During the arrivals phase of flight VHHH gave us vectors to the ILS 7R. Cause: GPS JammingSuggestion: Studying the long term effects of GPS jamming
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.