2022-05 · NASA ASRS report 1901663
Air carrier flight crew reported possible 5G issues on approach as well as confusing terminology and procedures regarding 5G interference.
IOE flight for upgrading CA (Captain). CA was PF (Pilot Flying) and [check pilot] was FO/PM (First Officer/Pilot Monitoring). Crew was expecting; had planned for; and briefed a visual approach to XYL backed up by the ILS. As we began our decent; ATC asked if we could accept XXR due to inbound flow for XYL. After a short discussion PF and PM agreed the change was acceptable and requested the RNP Z XYR. ATC confirmed we could expect that. Approach was loaded from FMS database and briefed as a backup for the visual to XYR. Winds were gusty with a reported and expected crosswind on landing. Once established on the approach; crew experienced what was believed to be strong mountain wave with the auto pilot oscillating above and below the flight director. PM reported suspected mountain wave to the tower. Approach and landing were as expected with gusts and a solid crosswind on landing. The following day; and prior to departure from ZZZ; the [check pilot] noticed FDC NOTAM listing the RNAV RNP Z XYR as NA except for aircraft using AMOC (Alternative Method of Compliance). At the time of the flight; CA/PF believed that the approach could only be used; as a backup to a visual approach due to a lack of AMOC relief. The [check pilot]/PM was of the mindset that the RNP-AR approach could be used despite lack of AMOC relief as long as it was not listed in the 5G NOTAM per crew bulletin. This started a series of in depth discussions on the topic of 5G throughout the day as time permitted.I believe there is still a good bit of confusion surrounding the 5G impact and interpretation of the guidance available and will be a topic for all my future threat based briefs. An increased vigilance in reviewing NOTAMS along with the separate FDC NOTAMS is critical.
On an IOE flight from ZZZ1 to ZZZ with Upgrading CA (Captain) as PF (Pilot Flying) and Check Pilot as FO (First Officer)/PM (Pilot Monitoring); the expected standard Visual Approach to XYL with ILS backup was planned and briefed. Around initial descent point; Center requested the flight to utilize XYR due to incoming flow for XXL. PF and PM agreed and proceeded to request and plan for the RNP Z XYR. Post flight discussion revealed that the PF believed that the RNP approach could not be conducted due to lack of AMOC relief unless used as a backup to a Visual Approach; the Check Pilot/PM was of the mindset that the RNP-AR approach could be used despite lack of AMOC relief as long as the approach was not listed in the 5G NOTAM as discussed in the Company crew bulletin. The Check Pilot did not notice the FDC NOTAM listing RNAV RNP Z XYR as unavailable due to 5G until during preflight of the departure flight the next day. During the initial portion of the approach; the crew experience what they believed to be strong mountain wave. It appeared that the autopilot was having difficulty keeping locked on the flight director in the vertical plane and was oscillating above and below the flight director. The PM reported suspected mountain wave at 4;500 ft. to Tower. In retrospect; this may have been caused by 5G interference. An uneventful final approach and landing followed. NoneBetter review of NOTAMS and separate FDC NOTAMS by crew. This would be assisted by simplification of the listed NOTAM to review. Example; I would never have time to take off in the same day if I plotted every unlit tower listed in the ZZZ1 NOTAMS.Updates to Company Documents for clarification and easier understanding; specifically:In the crew bulletin RNP-AR section; replace the statement 'Affected approaches will be listed by name in the 5G NOTAM and shall not be used' with the entire AOM-1 page X.X.X 'RNP-AR Instrument Approach Procedure Availability Statement.' This will provide standardization across documents and remove the incorrect statement that affected approaches will be listed in the 5G NOTAM when they are actually in the FDC NOTAMS as stated in the AOM.In all documents; change RNP-AR to simply RNP. I suspect the majority of line pilots are not aware of the term and definition of RNP-AR and may see it as separate from an RNP approach. To my knowledge; all of the Company RNP approaches used have at least one RF leg and all of them are RNP-AR. When I asked the upgrading CA if the RNAV RNP Z XYR was an RNP-AR; he initially said 'no'. He agreed it was when I pointed out the small note; but I do not blame him for the difficulty as individual approach plates are so non-standard in this regard. He was also of the mindset that if there was no AMOC relief; you could not utilize an RNP approach in IMC or night conditions. He; as I was just a few months ago; was unaware of the availability unless specifically listed as unavailable in the FDC NOTAMS. I think this is a common mindset and may result in crews not using available RNP approaches leading to potential diverts or alternate approaches in less optimal wind directions for landing.Revise the '5G C-Band Interference FAQs' for similar inconsistencies and provide a specific example of an FDC NOTAM making an RNP approach unavailable.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.
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