14 CFR 91.189 — Category II and III Operations: General Rules (Explained)

What is the difference between Category I, II, and III approaches?

ILS approach categories classify how low a crew may descend before needing outside visual references, with each tier demanding greater aircraft capability, ground infrastructure, and crew authorization. The categories are defined operationally in AIM 1-1-9 and applied through the approach procedure, the aircraft's letter of authorization, and the pilot's individual authorization.

The critical point: 14 CFR 91.189 does not hardcode DH or RVR numbers. The regulation instead defines which DH governs — the highest of three values — and leaves the specific numbers to the approach chart, the aircraft authorization, and the pilot's authorization. Applicants who understand this structure demonstrate a deeper grasp of the regulatory framework than those who simply memorize numbers.

What does 91.189 require for crew composition and authorization?

14 CFR 91.189(a) prohibits any person from operating a civil aircraft in Category II or III operations unless three conditions are met simultaneously.

1. 1
   The flight crew consists of a pilot in command and a second in command who hold the appropriate authorizations and ratings prescribed in 14 CFR 61.3. A standard instrument rating alone does not satisfy this requirement for Cat II or Cat III — each pilot must hold the specific category authorization.
2. 2
   Each flight crewmember has adequate knowledge of, and familiarity with, the aircraft and the procedures to be used. This is an active, crew-specific requirement — not a general currency standard.
3. 3
   The instrument panel in front of the pilot controlling the aircraft has appropriate instrumentation for the flight control guidance system being used.

The authorization requirement traces back to 14 CFR 61.3(f) for Category II and 14 CFR 61.3(g) for Category III. The PIC must hold a Category II or III pilot authorization for the category and class of aircraft — and, where applicable, the type. A second in command must hold at least a pilot certificate with the appropriate category and class ratings plus an instrument rating, or an ATP certificate with appropriate ratings.

What ground and airborne equipment does 91.189 require?

14 CFR 91.189(b) states that, unless otherwise authorized by the Administrator, no person may operate in Category II or III unless every required ground component and its related airborne equipment is installed and operating.

The ground system for Category II and III operations involves more than the basic ILS transmitters. It includes precision distance measuring equipment, a functioning inner marker or approved equivalent, a functioning approach light system, and runway touchdown zone and centerline lights for lower categories. Appendix A to Part 91 specifies the dual-system airborne equipment requirements for Category II: two independent localizer/glide slope receivers, dual gyroscopic pitch/bank and direction indicators, dual altimeters, dual airspeed indicators, and a flight control guidance system (either a flight director or autopilot approach coupler).

If any required component — on the ground or in the aircraft — is inoperative, the operation is prohibited unless the Administrator has issued specific authorization to proceed otherwise.

How does 91.189(c) determine the authorized decision height?

Under 14 CFR 91.189(c), the authorized DA/DH for a specific operation is the highest of three values:

• The DA/DH specified in the instrument approach procedure being flown.
• The DA/DH to which the pilot in command is individually authorized — set by the pilot's Category II or III authorization.
• The DA/DH for which the aircraft itself is equipped and authorized — set by the aircraft's type certificate, STC, or letter of authorization.

The word "highest" is operationally significant. If your personal authorization allows 100 ft HAT but the approach procedure specifies 150 ft HAT, you fly to 150 ft — the higher of the two governs. This prevents a pilot with a lower personal authorization from declaring a lower DH than the procedure itself allows.

What must a pilot do approaching and at the DA/DH?

14 CFR 91.189(d) and (e) establish the visual reference and missed approach rules that parallel the requirements in 14 CFR 91.175 for precision approaches generally.

The pilot may not descend below the authorized DA/DH unless visual references are acquired and maintained. If at any point the required visual references are lost after passing the DA/DH, 91.189(e) requires the pilot to immediately execute the appropriate missed approach procedure. There is no provision for continuing after reference loss — the go-around is mandatory.

For Category III operations without a published DH, 14 CFR 91.189(f) requires adherence to the provisions of the letter of authorization issued by the Administrator. That letter defines the alert height (if any) and the specific conditions under which the operation may continue to a landing without conventional visual reference acquisition.

Why does an instrument rating oral exam cover Cat II/III even though most Part 91 pilots never fly them?

The FAA Instrument Rating ACS (IRA) requires applicants to demonstrate understanding of precision approach operations, ILS system components, and the regulatory framework for low-visibility approaches. DPEs use Cat II/III questions not to test whether you plan to fly them, but to confirm that you understand why ILS capability is tiered, what crew and equipment authorizations exist, and how the regulatory structure limits who may descend to very low decision heights.

A well-prepared applicant can explain the category framework in two minutes: Cat I is the baseline precision approach any instrument-rated pilot may fly; Cat II and III require special crew authorization, additional aircraft equipment, functioning ground infrastructure, and progressively lower minimums. The authority for those minimums rests in the approach procedure, the aircraft authorization, and the pilot's personal authorization — not in a single number hardcoded in 91.189.

Frequently Asked Questions

Q: What does 14 CFR 91.189 actually require?

14 CFR 91.189 sets the general operating rules for Category II and III instrument approaches. It requires a two-pilot crew, each holding the appropriate Category II or III authorization under 14 CFR 61.3, and mandates that all required ground equipment and airborne systems be installed and operational before the operation begins.

Q: Do you need a special authorization to fly a Cat II or Cat III approach?

Yes. Under 14 CFR 91.189(a) and 14 CFR 61.3(f)/(g), the pilot in command must hold a Category II or Category III pilot authorization for the category and class of aircraft being flown. A standard instrument rating alone does not authorize Cat II or Cat III operations.

Q: What is the authorized decision height under 91.189(c)?

Under 14 CFR 91.189(c), the authorized DA/DH is the highest of three values: the DA/DH from the approach procedure, the DA/DH for which the PIC is authorized, and the DA/DH for which the aircraft is equipped. Whichever of those three is highest governs.

Q: Does 91.189 apply to Part 121 or 135 operators?

No. Under 14 CFR 91.189(g), certificate holders conducting operations under Parts 121, 125, 129, or 135 follow their respective operations specifications instead of 91.189. The section primarily governs Part 91 operators.

Q: What happens if ground components are out of service for a Cat II approach?

Under 14 CFR 91.189(b), no person may conduct a Category II or III operation unless all required ground components and related airborne equipment are installed and operating, unless the Administrator has specifically authorized otherwise.

Q: What must a pilot do if visual references are lost below the DA/DH on a Cat II approach?

Under 14 CFR 91.189(e), the pilot must immediately execute the appropriate missed approach procedure. The regulation prohibits descending below the authorized DA/DH without required visual references and mandates an immediate go-around if those references are not maintained.

Q: Why do instrument rating oral exams cover Cat II/III if most pilots never fly them?

DPEs test knowledge of approach categories because the IR ACS requires applicants to understand precision approach operations and ILS system limitations. Knowing what separates Cat I from Cat II from Cat III demonstrates understanding of ILS capability tiers, crew requirements, and the regulatory framework for low-visibility operations.

Q: What is the difference between Category IIIa, IIIb, and IIIc?

The three Category III subcategories reflect progressively lower minimums, each defined by the approach procedure and the letter of authorization under 14 CFR 91.189(f). Category IIIa uses a very low DH with an RVR requirement. Category IIIb uses a very low or no DH with a reduced RVR requirement. Category IIIc specifies no DH and no RVR limitation — a full autoland-to-rollout capability defined by the approach procedure itself.

Sources

• 14 CFR 91.189 — Category II and Category III Operations: General Operating Rules (Cornell LII)
• 14 CFR 61.3(f)/(g) — Category II and III Pilot Authorization Requirements (Cornell LII)
• 14 CFR 91.191 — Category II and III Manual Requirements (Cornell LII)
• Appendix A to 14 CFR Part 91 — Category II Operations: Manual, Instruments, Equipment, and Maintenance (Cornell LII)
• AIM 1-1-9 — Instrument Landing System (ILS) Category Definitions
• FAA Instrument Flying Handbook (FAA-H-8083-15B)

This article was researched from FAA primary sources (14 CFR Part 91 and Part 61 via Cornell LII, Appendix A to Part 91, AIM 1-1-9) and citing current regulatory text — drafted by MockDPE. Last updated: May 2026. If you spot an inaccuracy, email corrections@mockdpe.org.