The VASIs have been out of service for 740 days.
The KSQL VASIs have been out of service (OTS) since Jan. 11, 2019. Their replacement has experienced extensive delays; no definitive date has been set for their return to service; and replacement may take a extended/indiefinite period to complete.
VASIs are an important safety tool for night landings at KSQL— particularly since KSQL is a short field with a “black hole” on the primary approach, obstacles on each approach, and frequent strong and turbulent cross-winds. The FAA addresses relevant night landing issue as follows:
a. “An absence of surrounding ground features, as in an overwater approach over darkened areas . . . can create an illusion that the aircraft is at a higher altitude than it actually is. This illusion, sometimes referred to as the ‘black hole approach,’ causes pilots to fly a lower approach than is desired.” FAA, Pilots Handbook on Aeronautical Knowledge (PHAK), Ch. 17-10, https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/phak/media/19_phak_ch17.pdf
b. “Carefully controlled studies have revealed that pilots have a tendency to make lower approaches at night than during the day. This is potentially dangerous as there is a greater chance of hitting an obstacle, such as an overhead wire or fence, that is difficult to see.” FAA, Helicopter Pilots Handbook, https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/helicopter_flying_handbook/media/hfh_ch13.pdf
c. “Unless a pilot has many hours of training in instrument flight, flight should be avoided . . . at night when the horizon is not visible.” FAA, Pilots Handbook on Aeronautical Knowledge (PHAK), Ch. 17-6, https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/phak/media/19_phak_ch17.pdf
A disproportionate number of GA fatalities occur at night. Some recognized flight instructors discourage night landing in the absence of vertical guidance; others even advise prohibiting night operations under such conditions. Consider consulting with your flight instructor regarding current operational conditions at KSQL in light of the VASIs being OTS.
Finally, note that the FAA makes the following information available regarding airport lighting: https://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.list/parentTopicID/63