Landing from an Instrument Approach

To leave the decision altitude (DA) or minimum descent altitude (MDA) for the runway:

1. The aircraft is 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
2. The flight visibility is not less than the visibility prescribed for the approach
3. At least one of the required visual references for the intended runway is distinctly visible and identifiable

All three, the whole way down — lose any one below the minimums and the missed approach is mandatory (91.175(c), (e)).

• The approach light system (with a catch — see the next card)
• The threshold, threshold markings, or threshold lights
• The runway end identifier lights (REIL)
• The visual glideslope indicator (VASI/PAPI)
• The touchdown zone or TDZ markings, or TDZ lights
• The runway or runway markings
• The runway lights

Ten references; nine are runway-environment cues, one is the light system leading to it (91.175(c)(3)).

With only the approach light system in sight, I can descend to — but not below — 100 ft above the touchdown zone elevation, unless the red terminating bars or red side row bars are also distinctly visible and identifiable (91.175(c)(3)(i)). No red bars in sight by 100 ft above TDZE, and nothing else from the list visible: I go missed.

Flight visibility — what I observe from the cockpit — controls. Only the pilot can determine whether flight visibility meets the landing requirement: if it does, I continue to land even if reported visibility is lower; if it doesn't, I execute the missed approach regardless of what's being reported (IFH ch. 10; 91.175(c)(2)). Landing when flight visibility is below the prescribed minimum violates 91.175(d) — a separate prohibition from the descent rule.

The ALS penetrates the murk far enough from touchdown to give directional, distance, and glidepath information for the visual transition (IFH ch. 9). Common systems: ALSF-1 and ALSF-2, SSALR/MALSR and MALSF, and ODALS — many large airports add the high-intensity sequenced flashers ("the rabbit"), a ball of light running toward the runway twice per second (IFH ch. 9). I know my destination's system before the approach — identification at minimums must be instantaneous (IFH ch. 9).

REIL: a pair of synchronized flashing lights at the threshold corners for rapid, positive identification of the approach end (IFH ch. 9).

VASI: red/white light bars projecting a visual glidepath that provides safe obstruction clearance within the approach zone; on ILS runways the VASI angle normally coincides with the electronic glideslope. On glidepath: near bars white, far bars red. All red — I'm below; a safe obstruction clearance might not exist (IFH ch. 9). Both are 91.175(c)(3) references.

I keep flying the instruments while sampling outside, rather than abandoning the scan at the first ground contact — one of the most challenging moments of the approach, especially single-pilot (IPH ch. 4). Cautions:

• Shallow fog — I may see the runway from above, then lose the visual flare cues in the fog layer; I stay ready to go around
• Approaches with vertical guidance arrive stabilized, making the transition safer — I use the glidepath to touchdown even when visual
• I use the VGSI to confirm I'm positioned for a stabilized descent (AIM 5-4-5)

Very little. There is no implicit obstacle protection from the MDA/DA to the touchdown point — the visual segment is evaluated, but obstacles are allowed to penetrate it; seeing and avoiding them is my job (AIM 5-4-5). I fly the visual glidepath, not below it: some charts require "remain on or above VGSI glidepath until threshold" (AIM 5-4-5). I aim to cross the threshold at a nominal 50 ft (IPH ch. 4) — the typical charted TCH is 30–50 ft (IFH ch. 1). If I duck under, the clearance margins go with me.

Whenever a normal landing is no longer assured: the approach becomes unstabilized, the runway is occupied, windshear, or I'd need excessive maneuvering to reach the touchdown zone. A missed approach is required upon a rejected landing for any reason (IPH ch. 4) — and 91.175(e) applies until touchdown, so losing the required references or visibility in the flare still means I go around. Configuration and checklist discipline (VI.E S3) keep the go-around clean: I know my airplane's balked-landing procedure cold.

In low visibility the first cue is usually the sequenced flashers and approach light bars, then threshold cues, then runway texture. As the threshold approaches, the visual glidepath separates into individual lights — at that point I continue by reference to the touchdown zone markers (IFH ch. 9). The approach divides into two stages: the instrument stage on radio/GPS guidance, and the visual stage where ground contact provides accuracy — the most critical moment is the land-or-miss decision that joins them (IFH ch. 9). I call out what I see against what I briefed: expected lighting type, TDZ markings, runway length remaining.

Straight-in: I arrive on centerline, stabilized, usually on a 3° path — hold configuration, track the visual glidepath from DA/MDA or the VDP, and land in the touchdown zone at a normal descent rate (VI.B S14/S15; IPH ch. 4).

From a circle: I roll out of a visual pattern I built myself — the stabilized-approach gates still apply from the final turn: landing configuration, target speed, normal descent point. I land within the first one-third of the runway without excessive maneuvering (VI.D S8). Either way, the environmental factors — wind, windshear, runway surface, NOTAMs, wake turbulence — come from ATIS/ATC advisories and my own briefing (VI.E S2).

Three habits (VI.E S1, S3–S5):

• Transition at a defined point — DA/DH, MDA, or the VDP — to visual flight that allows safe maneuvering and a normal landing; no duck-unders, no salvage dives from the MAP
• Checklist complete — landing configuration verified before the visual segment gets busy
• Positive control to touchdown — I fly the airplane through the flare and rollout; the approach isn't over until taxi speed

Single-pilot resource management is graded here too: I brief the lighting, the go-around trigger points, and the balked-landing procedure before the FAF, so the decision at minimums is recognition, not deliberation (VI.E S5; IPH ch. 4).