grok

§ 91.175 – Takeoff and landing under IFR
(Source: 14 CFR § 91.175, eCFR)

Extracted Paragraph 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• (i) Operations on unpublished routes and use of radar in instrument approach procedures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

Brief Study Guide

Core Purpose
This regulation governs instrument approaches, descents below decision altitude/height (DA/DH) or minimum descent altitude (MDA), landing, missed approaches, and takeoff minimums under IFR.

Key Rules to Remember

1. Approaches (a)

Must use a standard instrument approach procedure (SIAP) from Part 97 for civil airports (unless FAA-authorized otherwise). Does not apply to U.S. military aircraft.

2. Authorized DA/DH or MDA (b)

Use the highest of:

• • The published value
  • The pilot’s personal minimum
  • The value appropriate to the aircraft’s equipment

3. Going Below DA/DH or MDA (c) – The “Three Requirements”

You may continue only if all of the following are met:

• • Continuously in a position for a normal descent and landing (touchdown-zone requirement applies to Part 121/135)
  • Flight visibility ≥ prescribed minimum
  • At least one of the listed visual references is distinctly visible and identifiable (approach lights, threshold, runway markings/lights, REILs, VASI/PAPI, touchdown zone, etc.).

Special rule for approach lights: may not descend below 100 ft above TDZE using approach lights alone unless the red terminating bars or red side-row bars are also visible.

4. Landing (d)

May not land if flight visibility is below the prescribed minimum (or if EFVS requirements under § 91.176 are not met).

5. Missed Approach (e)

Immediately execute the missed approach if the requirements of (c) or § 91.176 are not met at/below MDA or at/after the MAP/DA/DH, or if the airport becomes unidentifiable during a circling approach (except due to normal bank).

6. Takeoff Minimums (f) – Applies to Parts 121, 125, 129, 135
   • Use published Part 97 minimums if available.
   • If none published: 1 SM (≤ 2 engines), ½ SM (> 2 engines or helicopters).
   • Must use published Obstacle Departure Procedures (ODPs) or an ATC-assigned alternative (with additional performance requirements for 121/135/129 operators).

7. Other Notable Points
   • Military airports (g): Follow the military authority’s procedures and minimums.
   • RVR ↔ Visibility conversion (h): Use the table when RVR is prescribed but not reported (e.g., 2400 RVR ≈ ½ SM).
   • Radar vectors / unpublished routes (i): Maintain last assigned altitude until established on a published segment.
   • Procedure turns (j): Not allowed on radar vectors to final, timed approaches, or “No PT” procedures unless ATC clears you.
   • ILS components (k): Outer marker may be substituted by compass locator, radar, DME/VOR/NDB fix, or suitable RNAV; inner-marker rules are approach-specific.

Quick Memory Aids

• “Highest of three” for authorized DA/DH/MDA.
• “Position + Visibility + Visual reference” to go below.
• Execute missed approach the moment the requirements are no longer met.

This section is heavily tested on instrument-rating knowledge exams and checkrides. Focus on the visual-reference list and the exact conditions that allow (or require) a missed approach.