Bizjetlock - As ATCast says RAIM needs to recieve signals from at least five satellites.
In my original post I said
"As RAIM is predicated on the assuption that a majority of the GPS constellation is operating properly it may not even be able to detect a loss of integrity"
Most people remember the severe geomagnetic storm of March 1989
NASA's TDRS-1 communication satellite recorded over 250 anomalies caused by the increased particles flowing into its own sensitive electronics. Hundreds of satellites lost cotrol.
On Earth the Hydro Quebec power grid blackout left millions of people without power for 9 hours.
My question is at what level of Geomagnetic activity will scintillation errors affect integrity ...what about the less publicised storm of Feb 2008...did this affect GPS?
Also the Report of Solar Geophysical Activity forecasts are more accurate than our met forecasts...if they predict a disturbance in two days time there will probably be one.
Rudderrat....understand what you are saying about the Take off position / DME/DME...my concern is an incident from lining up of holes in the swiss cheese. A few years ago at the end of a long flight to AMS I had a total GPS failure...the take off position had drifted...there was a temporary dme replacing one of the normal stations and it happened on approach where line of sight meant fewer dmes to sample.
Tomorrow I fly to Bergamo
1 - No radar (procedural approach)
2 - Very high ground ..very close.
3 - Promulgated GPS inaccuracy due to ALPs
4- At the height of this particular solar event
Not an issue as (like women) I love GPS to bits...but don't trust it with my life (unless I know exactly what its up to...hence the question ). The approach will be done raw data...but we are in danger of breeding a generation of pilots who fly managed approaches below MSA without even selecting raw data backup. The problem with GPS errors is that when they happen they tend to be significant....blindly following the magenta line can really ruin your day.