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- Rick A
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Incoming large Coronial Mass Ejection (CME) - potential GPS and power grid trouble? Or, just more scare?
- Thread starter Rick A
- Start date
John Collins
En-Route
There was a big impact of a CME around 19:30Z to 2300Z yesterday. It wiped out LPV200, LPV, and LP service for a big part of the northern US.
Edit, there may not have been NOTAMs issued, the ones I quoted were for a different year. The WAAS LPV 200 coverage map, however, is correct.
Edit, there may not have been NOTAMs issued, the ones I quoted were for a different year. The WAAS LPV 200 coverage map, however, is correct.
Last edited:
Llewtrah381
Pattern Altitude
- Joined
- Apr 9, 2010
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- Llewtrah
Whoa! Looks like Canada has figured out how to push those our way!
Turns out the "space lasers" were Canadian.
RussR
Final Approach
I can't speak to effects on the power grid, but for RNAV, it's a very real thing. I was flying about a year ago for work (actually training a new hire), VMC fortunately, trying to load an RNAV approach when it kept giving errors. "SBAS not available". Several minutes ensued of me trying to figure out what I was doing wrong in the FMS, and trying to prove to my trainee that I really do know what I'm doing. Couldn't figure out what I was doing wrong, and it happened at multiple airports (in SE KS if I recall correctly). Once we landed for lunch we got the emails about a solar storm and possible SBAS/WAAS outages. Thank goodness, it wasn't me!
John Collins
En-Route
Although LPV and LP service was affected, LNAV was solid and still available for any approach. So was enroute and terminal navigation using GPS, they were not affected.
John Collins
En-Route
SBAS not available would be highly unusual and should not affect flying an RNAV approach using GPS. If SBAS was not available, RAIM should be used. I only know of a single 4 hour period since WAAS became operational that WAAS (aka SBAS) was not available. The WAAS outage was due to a software upload to the WAAS geo satellites that went bad. The recent outage of LPV and LP service didn't cause a WAAS outage, just that the required HPL/VPL values were exceeded.
RussR
Final Approach
That seems a little like semantics to me. If WAAS is "available", but the HPL/VPL values are exceeded, then an LPV approach is not flyable, which is the same effect. It's possible I'm remembering the FMS message wrong, but the result was that we couldn't fly LPV. Which was not a problem for us in VMC, but obviously could have been a very real impact in IMC.
John Collins
En-Route
No, there is a very significant difference. WAAS being unavailable means that the Geo satellites are not providing any correction or integrity data anywhere. In this instance, the corrections and integrity data were still being transmitted by the WAAS system, it is just that the integrity data indicates that the LPV and LP services are not available due to poor HPL and or VPL. The HPL for an LPV or LP is 40 meters. For LNAV it is 556 meters. The VPL for LPV is 50 meters and for LPV200 is 35 meters. In the 10-10 incident, the HPL and VPL values were above the maximums for some, but not all of the country. The WAAS system was totally available during the CME induced ionospheric storm. LPV and LP service was not available in much of the Northern US and Canada. If WAAS was unavailable, then WAAS could not be used anywhere in the SSV, even for LNAV, thus without WAAS, GPS navigation integrity would revert to using RAIM. For the most part, the ionospheric disturbance changes the time of arrival of the GPS signals at the receiver and therefore there is more error in the position. WAAS hasn’t failed. It is actively doing its job by tracking the increased uncertainty and letting you know that the precise integrity required for an LPV approach can no longer be guaranteed.