In the absence of visibility, they apparently went in to land on the GPS.
What are the "underwater" stones when entering GPS?
1. Is it known exactly which ellipsoid (datum) is used in the country?? (page 6 of manual GNS430)
2. Whether the reception of differential corrections (WAAS, EGNOS, etc.) is reliable?.
Maybe I'm wrong, but it turns out this picture:
- if the GPS is operating in diffrent mode (2 in field 6) sentence $GPGGA, the GPS will ignore
the incoming altitude from the barometer and will take the height of the GPS, as more accurate.
- What is the height of the GPS? This is the distance to the satellites.
- then "roll" the desired geoid / ellipsoid and get a height above the terrain.
A similar catastrophe was in Colombia on November 28, 2016 RJ-85, there in the airport area
the WAAS system operates.