When using two-bar VASI lights, what indicates you are on the proper glide slope?

When using a two-bar VASI (Visual Approach Slope Indicator) system, being on the proper glide slope is indicated by seeing the far bar red and the near bar white. This specific configuration signifies that the aircraft is at the ideal altitude for landing, aligning with the standard glide slope for the runway.

In a two-bar VASI system, the two colored bars provide a visual cue for pilots regarding their vertical position relative to the glide slope. The far bar being red indicates that the aircraft is at or below the correct glide path, while the near bar being white tells the pilot they are on the proper glide slope. This provides a clear visual reference that assists in achieving a safe approach.

The other configurations, such as far bar white and near bar red, would indicate that the aircraft is above the glide slope, and any combination of red and green in this context does not exist, as VASI systems typically use red and white. Therefore, the recognition of far bar red and near bar white as an indicator of the proper glide slope is fundamental for successful and safe landings.