FAA Instrument Rating Airplane (IRA)IFR Procedures and ChartsMedium
An ILS approach chart shows a minimums line labeled 'S-ILS 27' with a decision altitude, and a separate line below it labeled 'LOC' with a higher minimum descent altitude. Under which condition would a pilot use the LOC minimums instead of the S-ILS minimums?
- AWhen the reported visibility exceeds the ILS visibility minimum
- BWhen the glideslope is inoperative or not being used for the approach
- CWhen circling to a different runway after the final approach fix
- DWhen conducting the approach during nighttime hours
Show answer & explanationAnswer & explanation
Correct answer: B. When the glideslope is inoperative or not being used for the approach
The LOC minimums line applies when the approach is flown as a localizer-only (nonprecision) procedure because the glideslope is unusable, unmonitored, or not utilized. Since vertical guidance is unavailable, a higher MDA is used instead of the lower DA published for the full ILS.
Why the other options are wrong
- A. Incorrect — visibility conditions don't change which procedure (ILS vs LOC) is being flown.
- C. Incorrect — circling minimums are a separate line, not related to LOC-only operations.
- D. Incorrect — time of day does not determine which minimums line applies.
Localizer-Only (LOC) Minimums
Higher minimums published on an ILS approach chart for use when the glideslope is out of service or not used, converting the approach to a nonprecision localizer approach.
- LOC minimums use MDA, not DA
- Applied when glideslope is inoperative or unmonitored
- Always higher (less restrictive descent) than full ILS minimums
Memory trick: No Glideslope? Go LOC, Go Higher