Explaining 14 CFR § 91.175: When You Can Descend Below Minimums on an IFR Approach

If you’re a pilot flying under Instrument Flight Rules (IFR), understanding when you can safely descend below the published minimums on an approach is crucial for safety and compliance. The Federal Aviation Administration (FAA) outlines these rules in 14 CFR § 91.175, titled “Takeoff and landing under IFR.” This regulation covers various aspects of IFR operations, but in this post, we’ll zero in on the key part: the conditions under which you can operate below the Decision Altitude/Height (DA/DH) or Minimum Descent Altitude (MDA).

Whether you’re a student pilot preparing for your instrument rating or an experienced aviator brushing up on regs, this guide will break it down step by step. Remember, these rules are designed to prevent accidents by ensuring you have adequate visual references before committing to a landing.

What is 14 CFR § 91.175?

This section of the Code of Federal Regulations (CFR) governs takeoff and landing procedures when operating under IFR. It applies to most civil aircraft operations (with some exceptions for military aircraft). The regulation ensures that pilots use standard instrument approach procedures and adhere to visibility and positional requirements.

The most critical subsection for our discussion is paragraph (c): Operation below DA/DH or MDA. This is where the FAA spells out the “go/no-go” criteria for continuing below the minimums. Violating these can lead to enforcement actions or, worse, safety issues.

The Three Key Conditions for Descending Below Minimums

According to § 91.175(c), no pilot may operate an aircraft below the authorized MDA or continue an approach below the authorized DA/DH unless all three of the following conditions are met (except as provided in § 91.176 for straight-in landing operations below DA/DH or MDA using enhanced flight vision systems):

  1. Position for a Normal Descent: The aircraft must be continuously in a position from which a descent to a landing on the intended runway can be made at a normal rate of descent using normal maneuvers. For operations under Parts 121 or 135 (commercial ops), this descent must allow touchdown within the touchdown zone of the runway.

    In plain English: You need to be lined up properly. If you’re too high, too fast, or off-course, you can’t descend below minimums. This ensures a stabilized approach.

  2. Required Flight Visibility: The flight visibility must not be less than the visibility prescribed in the standard instrument approach procedure being used.

    Note that this is flight visibility (what the pilot actually sees), not the reported ground visibility. If the approach requires 1/2 mile visibility, you need at least that much when you break out.

  3. Visual References: Except for Category II or III approaches (which have their own rules specified by the Administrator), at least one of the following visual references for the intended runway must be distinctly visible and identifiable to the pilot:

    • The approach light system (but you can’t descend below 100 feet above the touchdown zone elevation using just the approach lights unless the red terminating bars or red side row bars are also visible).
    • The threshold.
    • The threshold markings.
    • The threshold lights.
    • The runway end identifier lights (REIL).
    • The visual glideslope indicator (VGSI, like VASI or PAPI).
    • The touchdown zone or touchdown zone markings.
    • The touchdown zone lights.
    • The runway or runway markings.
    • The runway lights.

    This list is exhaustive—pick one (or more) that’s visible, and you’re good to proceed, provided the other two conditions are satisfied.

If any of these aren’t met, you must execute a missed approach immediately as per paragraph (e).

Why These Rules Matter: Real-World Implications

Imagine you’re on an ILS approach in low visibility. You reach the DH, and you spot the approach lights but nothing else. Can you continue? Yes, but only down to 100 feet above touchdown zone elevation. If the red bars aren’t visible by then, go missed.

These requirements prevent “ducking under” minimums without proper cues, which has been a factor in many accidents. Always cross-check with your approach plate and current weather reports.

For Category II/III ops, special authorizations and equipment are needed, often involving autoland systems and lower minimums.

  • Military Aircraft: Exempt from some provisions.
  • Enhanced Vision Systems: See § 91.176 for ops using EFVS to go below minimums.
  • Landing Requirements: Even if you descend below minimums, you can’t actually land unless the visibility meets the approach requirements (paragraph (d)).
  • Missed Approach: If visual references are lost after descending, climb immediately.

Always consult the full regulation and your aircraft’s ops specs for specifics.

Conclusion

14 CFR § 91.175 is a cornerstone of safe IFR flying, emphasizing preparation, position, visibility, and visual cues before descending below minimums. By adhering to these rules, pilots mitigate risks in challenging conditions. If you’re training, quiz yourself on those visual references—they’re a common checkride question!

For the official text, check the eCFR. Stay safe in the skies!

Disclaimer: This post is for educational purposes only and not a substitute for official FAA guidance or legal advice.