Controlled flight into terrain danger due to incorrect glide slope

On some approaches such as SFO 01R GPS Approach & SFO 01L approach, the glide slope indicator is incorrect. There is high terrain blocking the glide slope to the runway. Hence the glide slope should be steeper to ensure a safe approach to the runway.

If you fly the glide slope indicator, especially in low visibility conditions on 01L you will have controlled flight into terrain (CFIT). I conducted a test with Approach mode autopilot turned on. The autopilot flew localizer and glideslope perfectly and was about to take me straight into a mountain. You can hear the radar altimeter announcing altitudes well below 500 ft on both approaches.

SFO might not be the only airport with this bug, there might be ILS approaches as well at other airports that also have this issue.

If you can look into this that would be appreciated.


GPS approaches are likely to be going through high terrain, or very low to the ground, this is one of the reasons why there may not be an ILS approach. IRL the glorescope would not be activated, they have been added for our benefit. Suggest that you research the airfields irl approach charts as this will show you how to approach the different runways , especially ones which are GPS Apr only.


The difference between ILS and GPS is that ILS accounts for terrain as part of the glide slope, GPS does not. That is why you are seeing those issues, the glideslope is just a general rate of descent and has no relation to the terrain. ILS assures terrain clearance. I would imagine that SFO doesn’t use that approach unless absolutely necessary. The 28s have ILS.


If I can remember correctly… This will be fixed with global (correct me if im wrong)

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GPS glideslopes do not take into account terrain or obstacles.

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