FAR Ninety-One Point One Seventy-Five, the Required Visual References That Determine Whether You Continue or Climb, and the One Hundred Foot Rule That Catches IFR Pilots Off Guard

FAR 91.175 requires that three conditions be simultaneously met before you may continue an instrument approach below minimums: required flight visibility, at least one approved visual reference from a specific FAA list, and a position from which a normal descent to landing can be made. Miss any one of them - or lose any of them after passing minimums - and you are required to execute the missed approach immediately. Most instrument-rated pilots know the general concept; far fewer know the specifics well enough to apply them correctly in the half-second window at decision altitude.

The Three Conditions That Must All Be True

FAR 91.175 does not offer a two-out-of-three standard. All three conditions must be met simultaneously. The moment any one of them is absent, the regulation requires an immediate missed approach - no grace period, no additional time to look.

The three gates are:

You have the required flight visibility listed on the approach plate
You can clearly identify at least one visual reference from the FAA’s approved list
You are in a position from which a normal descent to landing can be made

What “Required Flight Visibility” Actually Means

The required flight visibility is the number printed on the approach plate - not an estimate, and not what the field is currently reporting to ATC. You are the measuring instrument. There is no sensor on the aircraft nose. You are estimating from the cockpit based on what you observe through the windshield, which is precisely why the other two conditions also exist as independent requirements.

The Approved Visual References Under FAR 91.175

The regulation does not simply say “see the runway.” It provides a specific list. Identifying any one item from that list clearly satisfies the second condition.

The approved visual references are:

The approach light system (ALS)
The threshold, threshold markings, or threshold lights
Runway end identifier lights (REIL)
The visual glide slope indicator (VASI or PAPI)
The touchdown zone, touchdown zone markings, or touchdown zone lights
The runway, runway markings, or runway lights
The runway centerline, runway centerline markings, or runway centerline lights

One item from that list, clearly identified. That clears the second gate.

Why “Normal Descent Geometry” Is the Most Overlooked Condition

The third condition receives the least emphasis in training literature, but it carries significant legal and practical weight. If you break out of the clouds displaced, fast, or on a flight path that would require aggressive maneuvering to reach the touchdown zone, you do not have legal authority to continue.

“Normal” means you could fly the aircraft to a landing without abnormal inputs or exceptional technique. If conditions require a dive, a sharp turn, or anything beyond a standard stabilized descent, the third condition is not met - and the missed approach is required regardless of what you can see.

Precision Approaches: Decision Altitude Is a Decision Point

On an ILS or other precision approach, you descend to your Decision Altitude (DA). The DA is not a place to level off and search. It is a decision point: by the time your altimeter reads the DA, the visual picture should already be forming through the windshield. If all three conditions are satisfied, continue. If they are not, execute the missed approach immediately.

There is no regulatory authority to descend below DA without meeting all three conditions.

Non-Precision Approaches: The MDA and the Missed Approach Point

Non-precision approaches use a Minimum Descent Altitude (MDA) rather than a DA. The procedure differs: descend to the MDA, level off, and hold that altitude while tracking down the final approach course. You may not descend below the MDA until all three conditions are simultaneously met.

When you reach the Missed Approach Point (MAP) - typically time-based or fix-based on non-precision approaches - without the required visual references, you are required to climb immediately. The MAP is not a suggestion. There is no provision for one additional look.

The 100-Foot Rule: What Approach Lights Alone Actually Authorize

This is the provision that most reliably catches experienced IFR pilots off guard.

If the approach light system is your only visual reference, FAR 91.175 permits descent below minimums - but limits that descent to 100 feet above the touchdown zone elevation. No lower. The regulation explicitly states that approach lights alone do not authorize descent below 100 feet above the touchdown zone elevation unless the red terminating bars or the red side row bars of the approach light system are also visible.

The practical sequence: approach lights visible → continue below minimums → stop descent at 100 feet above the touchdown zone unless you acquire another reference from the approved list. If you arrive at 100 feet above the touchdown zone with only the approach lights and nothing else, you go missed.

This is where pressure and confidence become hazardous. The approach is stable. The lights are firing. The runway feels close. But proximity is not the regulatory standard. The 100-foot rule exists because approach lights guide you toward the threshold - they do not confirm your precise position relative to the runway surface. Below that altitude, without seeing the touchdown environment directly, you are operating on assumption. The regulation does not permit that.

Why This Matters: Spatial Disorientation in Low Visibility

Approach lights are powerful and reassuring, particularly at night. They are not a substitute for visual confirmation of where the aircraft will touch down. Spatial disorientation is a genuine threat in low-visibility night conditions, and confidence in a stable approach can mask the absence of actual situational awareness. The 100-foot floor exists because the consequences of being wrong below it leave no margin.

Scenarios Where the Go-Missed Decision Gets Complicated

Losing visual reference after passing minimums. FAR 91.175 requires that flight visibility and visual reference be maintained continuously from the point of descent below minimums through landing. If you acquire the runway at DA and ground fog subsequently rolls across the threshold, you go missed immediately. There is no waiting for conditions to improve.

Crosswind beyond aircraft limits. The third condition requires a position from which a normal landing can be made. If the crosswind is gusting beyond the aircraft’s demonstrated crosswind component and a safe landing is not achievable, the missed approach is required - not merely permissible. Conditions preventing a normal landing eliminate the third condition regardless of visibility.

System uncertainty or equipment failure. The regulation establishes a floor on what is required, not a ceiling on good judgment. An uncertain gear indication or intermittent braking are examples where a missed approach is correct even if all three regulatory conditions are technically met. Climbing buys time, altitude, and options that the regulation does not require but airmanship demands.

What Seeing the Runway Does Not Authorize

A common misconception: that acquiring the runway in sight authorizes whatever maneuvering is necessary to land. FAR 91.175 does not say that. Visual acquisition of the runway satisfies one condition. You still need the required flight visibility. You still need normal approach geometry.

An unstabilized approach that happens to have the runway in sight is still an unstabilized approach. Breaking out at minimums high, fast, or significantly displaced from centerline is almost always a missed approach situation - even when the visual picture is technically present. Most instrument approach accidents do not happen because the pilot could not see. They happen because the pilot was behind the aircraft when they broke out, and made the wrong call about what to do with five seconds and four hundred feet remaining.

ATC’s Role - and Its Limits

ATC can instruct you to execute a missed approach. When a controller issues that instruction, it is a clearance revision: climb, follow the published missed approach procedure, and acknowledge on the radio. Controllers may have information unavailable to you - traffic on the runway, a vehicle crossing, a condition just reported by the preceding aircraft.

What ATC cannot do is authorize you to continue an approach when you don’t have the required visual references. No controller can give you permission to land below minimums. The three conditions are your responsibility as pilot in command. A controller’s clearance does not transfer that responsibility or provide a defense after the fact.

Preparation Before You Enter the Clouds

The go-missed decision is significantly easier to make correctly when you have already considered what you are looking for. Before beginning the approach, spend five minutes answering these questions: What visual reference am I most likely to acquire first at this airport? What does the approach light system look like here - is it an ALSF-2, a MALSR, or something simpler? Where is the threshold relative to where I expect to break out of the overcast?

Brief the missed approach as an actual plan, not a formality. Think through the climb, the heading, the altitude, the fix. A briefed missed approach is an option you planned to use if needed - not a contingency you hope to avoid. Pilots who get into trouble on approaches have often already mentally committed to landing before they’ve committed visually. When the picture doesn’t come together, they improvise. That improvisation, at low altitude, in low visibility, at night, is where accidents begin.

The FAA is not asking for perfect visibility, a full view of the runway, or a textbook-ideal approach. It is asking for one item from a short list, enough flight visibility to see where the aircraft is going, and a reasonable flight path to the touchdown zone. Those are minimum standards. When they aren’t present, the aircraft belongs pointed up.

A missed approach or diversion is the system working correctly. A bent airplane because the floor was pressed through is the outcome the regulation was written to prevent.

Key Takeaways

Three conditions must all be simultaneously met under FAR 91.175 to continue below approach minimums: required flight visibility, at least one approved visual reference, and a position allowing a normal descent to landing.
Decision Altitude (precision) is a decision point - not a place to level off. Minimum Descent Altitude (non-precision) is a floor held until conditions are met or the MAP is reached.
Approach lights alone authorize descent no lower than 100 feet above the touchdown zone elevation unless the red terminating bars or red side row bars are also visible.
Visual references must be maintained continuously from the point of descent below minimums through landing. Losing them after passing DA or leaving MDA requires an immediate missed approach.
A missed approach is a normal operation. The pilots who get into trouble are the ones who mentally committed to landing before they committed visually.