You are correct, Rafael. Let me add a couple of points that support your post.
These are my opinions and comments and in no way reflect the views/comments of the organization I work for or aviation groups I am a member of.
- While we know U.S. MOAs and ATC is aware of military activities/exercises, one hot-spot that is often missed when GNSS interference is being discussed is the US-Mexico border. Please be on alert when operating along the southern border.
- The frequency of interference (both jamming and/or spoofing) in Eastern Europe, Middle East, Korean border and parts of China have increased quite significantly. Latest data from July-Aug 2024 report over 41,000 flights (commercial/121) have been affected. Sadly, the locations/areas of interference, patterns and type of interferences are also increasing and getting more complicated.
- Many modern-day systems rely on GNSS inputs (PNT data). TAWS/EGPWS, Hybrid IRS/INS, WxRadar, ADS-B, CPDLC, Fuel computers, etc… Depending on the location and severity of the interference, the effects to these systems vary and are inconsistent. As an example, crews have reported getting terrain alerts while operating at flight levels with no terrain threat in sight. Other crews reported not getting a terrain alert. CPDLC relies on accurate timestamps. Some crews have not had issues while some have had issues. For me, managing the erroneous alerts/information/data during an enroute/cruise leg is “manageable”. The risks increase on departure, arrival and approach due to high task loading, loss of SA, and many more. Another big issue is the risk of normalization of deviations/deviance.
Some OEMs and operators have begun producing/releasing mitigation procedures due to GNSS interference. If you operate an aircraft that has an OEM or Operator mitigation strategy, please follow it.
If you don’t have an OEM/Operator procedure, please consider the following advice/tips in your ops. NOTE: These are common recommendations (not requirements) that you will need to consider whether they are valid for you and your operation; consider with regard to your MMEL/MEL/Required equipment list; consider with regard to your regulations, route and navigation requirements.
- Know the known areas of interference
- Include GNSS interference and “what you are going to do” in your preflight and briefings (whether self or crew)
- Prior to departure (especially when departing near or from a known interference area), verify and log your position, system initializations, and time against a known value or charted position.
- In flight, prepare for interference. Some crews reported as early as 45mins or 300nm prior to entering a known interference area. Start increasing your vigilance on GNSS status, navigation and pilot reports. When able, log current track, cardinal heading, time, and cardinal positions and frequencies of conventional navaids. Know that there are some instances when jamming precedes spoofing, but not all the time. There are some instances when jamming happens after spoofing … but not all the time. Finally, there are instances where jamming only happens … or instances when spoofing only happens. Just be prepared.
- As soon as you detect GNSS anomalies or system anomalies indicatinig an interference (GNSS Fail, FMS/GNSS mis-compare/ large shift in GNSS time values / autopilot wandering / large increase in EPU values vs. ANP values / system warnings or failures, and others) let ATC know. You may have to ask vectors and lower your level of automation. ATC may be very busy vectoring other affected aircraft around, but they can give you an initial heading and altitude to fly (at the very least). If flying RNAV/RNP routes, please let ATC know because separation and route accuracy may be affected. If in VMC, look out the window … depending on the airspace, it may be quite busy.
- Crews have reported that the earlier they deselect GNSS as an input source, the better. Some avoid GNSS-based direct-to routings and prefer to route using conventional navaids, reverting to conventional navigation if/when available. Regardless, maintain your spatial awareness and, if available, verify your position and track using conventional navaids if available. Verify also time using an accurate mechanical clock. For these alone, some crews have already re-implemented the master log.
- After exiting the interference area and you get back to GNSS as an input source to navigation, allow a period of GNSS normalcy (est. 10 minutes). Some attacks may have long-lasting effects. Some crews even had to reset the GNSS receiver on the ground after landing.
- Arriving or doing an approach in (or near) an area of interference, be prepared to convert to conventional navaids. And as mentioned earlier, GNSS data is used by a lot of other aircraft systems, so situation and spatial awareness is key. If IFR, know and abide by the charted procedure. If VFR, also know and abide by an appropriate/applicable IFR chart and its limitations.
I hope my post can increase awareness regarding this threat to safety-of-flight. While we are relatively inconvenienced/unhindered/safe in the U.S., events and trends elsewhere has shown that it can be a major factor here as well because technology and skills for jamming and spoofing are becoming cheaper, easier to do, and more complicated. ATC is working on their mitigation procedures. U.S. DOD/Air force have begun work on the U.S. GPS system to improve its resiliency. Aviation authorities have started to advise us in letters and circulars more and more. Join discussion groups to learn, know and share more about this threat. Train for this type of threat.
Fly safe!