claude

The eCFR page still returned a rate-limit error, so I pulled the text from Cornell's LII copy of the eCFR, which I could read in full.

§ 91.175 Takeoff and landing under IFR: headings

• (a) Instrument approaches to civil airports
• (b) Authorized DA/DH or MDA
• (c) Operation below DA/DH or MDA
• (d) Landing
• (e) Missed approach procedures
• (f) Civil airport takeoff minimums
• (g) Military airports
• (h) Comparable values of RVR and ground visibility
• (i) Operations on unpublished routes and use of radar in instrument approach procedures
• (j) Limitation on procedure turns
• (k) ILS components

Correction: I previously mentioned a possible paragraph (l) for EFVS. There isn't one. EFVS operations now live in § 91.176, which (c) and (d) cross-reference.

Study guide

(a) Approaches to civil airports

• Unless the FAA authorizes otherwise, use a standard instrument approach procedure prescribed in part 97. This doesn't apply to U.S. military aircraft.

(b) Authorized DA/DH or MDA

• The authorized minimum is the highest of three values:
  • the one in the approach procedure
  • the one prescribed for the pilot in command
  • the one appropriate for the equipment used

(c) Operation below DA/DH or MDA

You may not go below the MDA or continue below the DA/DH unless all three conditions are met:

1. You can make a normal-rate descent to the intended runway using normal maneuvers. For part 121 and 135, that descent must also allow touchdown in the touchdown zone.
2. Flight visibility is at least what the approach requires.
3. At least one required visual reference is distinctly visible and identifiable. Cat II and III approaches are exempt because the Administrator specifies their references.

The ten visual references are:

• approach light system
• threshold
• threshold markings
• threshold lights
• runway end identifier lights
• visual glideslope indicator
• touchdown zone or its markings
• touchdown zone lights
• runway or runway markings
• runway lights

The approach lights alone get you no lower than 100 ft above the touchdown zone elevation. To go lower, the red terminating bars or red side row bars must also be visible.

(d) Landing

• You can't land if flight visibility is less than the visibility prescribed in the approach being used. For § 91.176 operations, the (a)(3)(iii) or (b)(3)(iii) requirements of that section apply instead.

(e) Missed approach

Execute a missed approach immediately when:

1. Under (c) or § 91.176, the requirements aren't met either below the MDA, or at the missed approach point (including the DA/DH) and at any time after that until touchdown.
2. During a circling maneuver at or above the MDA, an identifiable part of the airport isn't distinctly visible. The exception is when the loss of sight comes only from a normal bank of the aircraft.

(f) Takeoff minimums

• This applies to parts 121, 125, 129, and 135 only.
• Use the part 97 takeoff minimums. If none are published, use these:
  • 1 SM for aircraft with two engines or less (not helicopters)
  • 1/2 SM for aircraft with more than two engines
  • 1/2 SM for helicopters
• If the airport has published ODPs for the runway, use them or an ATC-assigned alternative. Parts 121, 135, and 129 also need an obstacle clearance procedure that meets their performance limitations.

(g) Military airports

• Follow the approach procedures and takeoff and landing minimums set by the military authority at that airport.

(h) RVR and visibility

• If RVR minimums are prescribed but RVR isn't reported for your runway, convert the RVR to ground visibility using the table below. Cat II and III are excepted.

(i) Unpublished routes and radar

• Radar can support approaches based on other navaids, and radar vectors can provide course guidance.
• On an unpublished route or while being vectored, maintain your last assigned altitude after approach clearance until established on a published route or approach segment, unless ATC assigns a different one. After that, published altitudes apply for each segment. Also comply with § 91.177.

(j) Procedure turns

• No procedure turn unless ATC clears you for one when you're radar vectored to the final approach course, on a timed approach from a holding fix, or flying an approach marked "No PT."

(k) ILS components

• The basic components are the localizer, glide slope, and outer marker, plus an inner marker for Cat II and III.
• The outer marker can be replaced by:
  • a compass locator
  • PAR or ASR
  • DME, VOR, or NDB fixes authorized in the approach
  • a suitable RNAV system with a fix identified in the approach

Exam tips

• Know the "highest of three" rule in (b).
• Memorize the three conditions in (c) and the 100 ft rule for approach lights.
• Remember that (f) takeoff minimums apply to commercial operators, not Part 91.
• Practice the RVR conversion table.