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Instrument rating · ACS IR.VI.B · lesson pack

Precision Approach

Why this one matters

Precision approaches take you lowest, often to 200 feet above the runway. That leaves little room for an unstable approach or a late decision. Continuing below the DA without the runway clearly in sight, or chasing the needles near minimums, is how airplanes land short or hit obstacles. A stable final and a firm decision at the DA keep it safe.

1 · Know these cold

  • •Precision approaches are ILS, GLS and PAR. LPV and LNAV/VNAV are approaches with vertical guidance (APV): also flown to a DA, but not precision, so for alternate planning they count as nonprecision (800-2).(Instrument Procedures Handbook (FAA-H-8083-16B), Approaches; AIM, Chapter 1 (navigation aids, GPS and WAAS))
  • •The DA is a decision point, not a floor: if the required references aren’t distinctly visible, start the missed at the DA without leveling off. A brief dip below DA while the missed begins is expected.(14 CFR 91.175)
  • •Set a descent rate as you intercept the glidepath: about 5 times your groundspeed for a 3° glideslope (90 knots ≈ 450 fpm).(Instrument Flying Handbook (FAA-H-8083-15B))
  • •Localizer and glideslope get more sensitive as you get closer: small corrections, and no more than 3/4-scale deflection.(Instrument Procedures Handbook (FAA-H-8083-16B), Approaches)
  • •Identify the localizer by its Morse code before relying on it; for LPV, confirm the LPV annunciation.(AIM, Chapter 1 (navigation aids, GPS and WAAS))
  • •Adjust minimums for category, NOTAMs, inoperative aircraft or navigation equipment and visual aids (DA as well as visibility), using the Inoperative Components Table and chart notes. Glideslope out: use the localizer (LOC) line's MDA if the chart has one; if not, the approach can't be flown as published.(Terminal Procedures Publication, Inoperative Components or Visual Aids Table; IPH)
  • •Checkride standard: from the FAF to DA, no more than 3/4-scale deflection of either needle, airspeed ±10 knots.(Instrument Rating ACS (FAA-S-ACS-8C), IR.VI.B.S12)

2 · The lesson

Systems and indications
  • An ILS has a localizer (lateral) and glideslope (vertical, usually 3°). The localizer is about four times as sensitive as a VOR; full deflection is a few degrees off course.(AIM, Chapter 1 (navigation aids, GPS and WAAS))
  • RNAV (GPS) approaches with LPV or LNAV/VNAV minimums give vertical guidance from WAAS or baro-VNAV. Confirm the mode annunciation before the FAF.(AIM, Chapter 1 (navigation aids, GPS and WAAS))
  • Identify the localizer by Morse code, check for flags, and watch for false glideslope indications above the published path; intercept from below.(AIM, Chapter 1 (navigation aids, GPS and WAAS))
  • GPS can be affected by interference or jamming; ground-based aids can have outages. Check NOTAMs.(AIM, Chapter 1 (navigation aids, GPS and WAAS))
  • Vertical-guidance limits: if an LPV downgrades to LNAV, fly the minimums the receiver now annunciates (the LNAV MDA) or go missed. Baro-VNAV has published temperature limits and needs a local altimeter setting.(AIM, Chapter 1 (navigation aids, GPS and WAAS))
The descent and minimums
  • Plan the descent rate: groundspeed times 5 for a 3° path. A headwind lowers groundspeed and the rate needed.(Instrument Flying Handbook (FAA-H-8083-15B))
  • Inoperative equipment (approach lights, for example) can raise the visibility minimum: look it up in the Inoperative Components Table at the front of the TPP, and check the chart notes, which can override it for that approach.(Terminal Procedures Publication, Inoperative Components or Visual Aids Table; IPH)
  • Energy: fly a stable speed and configuration, with small pitch and power changes to hold the glideslope.(Instrument Procedures Handbook (FAA-H-8083-16B), Approaches)
At the decision altitude
  • At the DA, the decision is made: continue only if you meet 91.175 (normal descent, flight visibility and a required visual reference); otherwise start the missed approach right away.(14 CFR 91.175)
  • The approach-light rule is two steps. (1) With the approach lights as your only reference, you may descend no lower than 100 feet above the touchdown zone elevation (TDZE). (2) If the red terminating bars or red side-row bars are also distinctly visible and identifiable, the approach lights let you go below 100 feet. Work the number out from the chart before the approach: TDZE plus 100 feet is your floor on the altimeter.(14 CFR 91.175)
  • Which lights have red bars: ALSF-1 has red terminating bars; ALSF-2 has red side-row bars in the inner 1,000 feet. MALSR, MALS and ODALS have none, so on those lights alone you never go below TDZE + 100; you need another listed reference (threshold, REIL, VASI, touchdown zone, runway, or their markings or lights) by then, or you go missed.(14 CFR 91.175; AIM, Chapter 2 (approach and runway lighting))
  • The lights never cure the other conditions: all three in 91.175(c) must hold the whole way down: continuously in position for a normal descent with normal maneuvers, the required flight visibility, and a listed reference distinctly visible and identifiable, not just glimpsed. And 100 feet above TDZE is a floor on a continuous descent, not a second decision altitude: stay on the glidepath, and if you reach it with nothing beyond the white approach lights, go missed right then.(14 CFR 91.175)
  • An unstable approach near minimums, such as full-scale deflection or a high sink rate, is a go-around.(Instrument Procedures Handbook (FAA-H-8083-16B), Approaches)
  • Below DA with the references: a normal-rate descent on a stabilized visual path to the aiming point, and a normal landing in the touchdown zone. No diving or ducking under the glidepath.(Instrument Procedures Handbook (FAA-H-8083-16B), Approaches; Instrument Rating ACS (FAA-S-ACS-8C), IR.VI.B.S14-S15)
  • The rest of the task: recognize inaccurate or inoperative instruments and say so; run the checklists; use the MFD for awareness; and manage the workload with SRM.(Instrument Rating ACS (FAA-S-ACS-8C), IR.VI.B.S5, S7, S16, S17)
Flying it: setup, automation and configuration
  • Brief the chart before you need it: frequencies, final approach course, FAF altitude, minimums, the missed approach, and notes.(Instrument Procedures Handbook (FAA-H-8083-16B), Approaches)
  • Tune, identify (Morse code) and confirm every navaid; for GPS, check the approach is loaded and the correct mode annunciates before the FAF.(AIM, Chapter 1 (navigation aids, GPS and WAAS))
  • Know what the autopilot and navigator will do next, and be ready to hand-fly. Automation confusion on an approach is a known accident pattern.(Risk Management Handbook (FAA-H-8083-2A))
  • Configure in stages, per the POH: approach configuration and speed by the FAF so the final segment needs only small changes; final flaps when landing is assured (when circling, not until you leave the MDA). Know the missed approach configuration too.(Your airplane's POH/AFM)
  • Fly the procedure as published or as cleared. If you can’t comply with a clearance, say "unable".(AIM, Chapter 5, Section 4 (arrival and approach procedures))

Want it all on one page, with scenarios? Read the full lesson.

On the flight

ACS standards

  • Before the final approach segment: altitude ±100 feet, heading ±10°, airspeed ±10 knots, no more than 3/4-scale CDI deflection.(Instrument Rating ACS (FAA-S-ACS-8C), IR.VI.B.S9)
  • From the FAF to DA, no more than 3/4-scale deflection of the vertical or lateral guidance, airspeed ±10 knots.(Instrument Rating ACS (FAA-S-ACS-8C), IR.VI.B.S12)
  • Immediately initiate the missed approach at the DA when the required references aren’t unmistakably visible.(Instrument Rating ACS (FAA-S-ACS-8C), IR.VI.B.S13)

What your instructor is watching for

Your instructor watches whether you identify the localizer, set the descent rate at glideslope intercept, make small corrections, stay within 3/4 scale, and go missed promptly at DA.

3 · Say it out loud

Answer each one out loud, then check yourself and mark how it went.

  1. Remember Recall it

    “What descent rate keeps you on a 3° glideslope at 100 knots groundspeed?”

  2. Understand Explain why

    “Why can’t you level off at the DA like at an MDA?”

  3. Apply Use it on a flight

    “At DA you see the approach lights but not the runway. What do you do?”

4 · Common mistakes

  • Chasing the needles.

    Overcorrections grow as the needles get more sensitive.

    Instead: Small, early corrections; hold a heading and descent rate.

  • Continuing below DA hoping to see the runway.

    Below the protected path without references.

    Instead: Decide at DA.

  • Not identifying the localizer.

    Wrong or out-of-service signal.

    Instead: Listen to the Morse ident.

5 · Quick check

Answer, then reveal. Flag anything you want to see again.

  1. 1. What minimum does a precision approach use?

  2. 2. Which RNAV minimums include vertical guidance?

  3. 3. How do you estimate the descent rate for a 3° path?

  4. 4. Checkride limit on needle deflection from FAF to DA?

  5. 5. Why intercept the glideslope from below?

  6. Scenario6. At DA in fog, nothing in sight. What do you do?

Trained it? Now prove it: practice precision approach out loud with our examiner.

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Connect it

One situation that runs across this lesson and its neighbors in the same ACS area. Decide first, then check.

Connect it · Instrument Approach Procedures

On an LNAV approach you reach MDA two miles before the missed approach point. At one mile you see approach lights, but not the runway.

Can you descend, how far, and what makes you go missed? Decide, then see the worked answer

Under 91.175(c) you may leave MDA only when the airplane 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, the flight visibility is at least the published minimum, and at least one of the listed visual references for that runway is distinctly visible and identifiable. The approach light system counts, but it lets you descend only to 100 feet above the touchdown zone elevation. That's a floor for the descent, not a target to level off at. Below it you need the red terminating bars or red side row bars, which only ALSF-1 and ALSF-2 systems have, or another 91.175(c)(3) reference: the threshold, its markings or lights, the REIL, the VASI or PAPI, the touchdown zone, or the runway, its markings or lights, distinctly visible and identifiable. Reach 100 feet without one and go missed immediately. Go missed at the MAP if you don't have the references. If you lose them below MDA, go missed at once too. Obstacle clearance on the missed approach assumes it starts at or above MDA at the MAP, so climb, re-intercept the published missed approach as safely as you can, and contact ATC as soon as possible.

14 CFR 91.175(c)-(e); AIM 5-4-21

Brings together: Non-precision Approach · Missed Approach · Landing from an Instrument Approach

Teaching this? The instructor lesson plan →

Study aid, not FAA guidance. Sources: Instrument Procedures Handbook (FAA-H-8083-16B); Instrument Flying Handbook (FAA-H-8083-15B); Aeronautical Information Manual (AIM); 14 CFR; Instrument Rating ACS (FAA-S-ACS-8C); Terminal Procedures Publication (TPP). Checked against current sources 2026-11-13.