LPV Approaches Explained: How WAAS Builds an ILS-Like Glidepath, Lateral Scaling, LPV-200 Minimums, Equipment, Annunciations and Downgrades, and Why It's an APV Not a Precision Approach
Updated: Oct 27
If you’ve flown instrument approaches in the last decade, you’ve watched RNAV (GPS) plates multiply, each with a stack of minimums lines — LPV, LNAV/VNAV, sometimes LP, and LNAV. LPV — Localizer Performance with Vertical guidance — is the one that feels like an ILS: a lateral course that tightens as you near the runway and a smooth glidepath to a decision altitude. It has transformed IFR access at thousands of runways that could never justify an ILS, and it does it with no ground transmitter at the airport, no critical areas, and no false glideslopes.
But LPV isn’t an ILS, and the differences matter: it depends on WAAS integrity in real time, it can downgrade to a higher line of minima on the day, it’s classified as an approach with vertical guidance rather than a precision approach (with a real consequence for alternate planning), and its glidepath is a computed geometric path that still ends at a barometric DA. This post covers what LPV is, how WAAS builds the path, what you’re actually following, the lateral scaling, minimums, equipment, annunciations and downgrades, technique, the limitations, where LPV sits next to ILS and GLS, and the checkride questions.
Study this full length lesson (video, podcast, flashcards, and quiz) here: Full Length Lesson >
What LPV Means
Localizer Performance with Vertical guidance.
The definition:
A line of minima on an RNAV (GPS) approach that provides lateral guidance with localizer-like angular scaling and a WAAS-computed geometric glidepath, flown to a Decision Altitude
“Localizer performance” refers to the lateral precision — the course is designed and flight-checked to perform like a localizer
“Vertical guidance” refers to the glidepath — approved, flown to a DA, not advisory
The lowest line on most RNAV (GPS) plates
The classification:
The FAA classifies LPV as an approach with vertical guidance (APV) — AIM 5-4-5 lists LPV and LNAV/VNAV under APV minima
It is not a precision approach, even though it flies like one and can reach the same 200-foot DA as a CAT I ILS
The classification follows the standards and procedure-design criteria the service is built to, not the hardware (GLS is satellite-based and IS a precision approach)
In ICAO’s newer vocabulary, an LPV is a 3D approach, and an LPV with a DA below 250 feet is a Type B operation — the same operational class as CAT I ILS
Why the classification matters:
Alternate planning (91.169, AIM 1-1-18): you may not plan the alternate on LPV minima; plan on LNAV or circling with the 800-2 nonprecision/APV standard, plus the GPS/WAAS alternate rules
Vocabulary on the oral: “Is LPV a precision approach?” — “No, it’s an APV”
Everything else about flying it is precision technique
Classify it as an APV; fly it like an ILS
How WAAS Builds the Path
ILS-style cues from satellites plus augmentation.
Plain GPS isn’t enough for vertical guidance:
Unaugmented GPS gives you position accurate to tens of meters, with integrity (RAIM) good enough for en route, terminal, and LNAV approaches — lateral only
Vertical guidance to a 200-foot DA needs accuracy of a few meters and, more importantly, a guarantee: the receiver must know, right now, that the vertical position error is bounded tightly enough to be safe, or warn you within seconds if it isn’t
That guarantee is integrity, and it’s what augmentation provides
Accuracy gets you close; integrity lets you trust it to a DA
What WAAS adds:
A network of ground reference stations across the U.S. monitors the GPS satellites continuously
Master stations compute corrections for satellite clock and orbit errors and for ionospheric delay, plus integrity information about each satellite’s health
The corrections and integrity messages are uplinked to geostationary satellites, which broadcast them on a GPS-like frequency so your receiver gets them with the same antenna
The result is a corrected, monitored position solution with protection levels the receiver can compare against limits
Protection levels and alert limits:
Your WAAS receiver continuously computes a horizontal protection level (HPL) and a vertical protection level (VPL) — bounds on how wrong its position could be
Each level of service has alert limits; LPV requires the tightest — a vertical alert limit of 50 meters for standard LPV, and 35 meters for LPV-200 minima
If the VPL exceeds the LPV vertical alert limit at any moment, the receiver won’t offer LPV — it downgrades
That’s the “I can guarantee my performance right now, or I’ll tell you” behavior that makes vertical guidance legal
Other SBAS systems:
WAAS is the U.S. SBAS; EGNOS serves Europe, MSAS Japan, GAGAN India, and others are coming online
LPV procedures exist wherever an SBAS provides coverage
A WAAS receiver uses whichever SBAS covers the region
Same concept, different footprints
What You’re Actually Following
A computed path, not a beam.
The final approach segment (FAS) data block:
Each LPV procedure is defined by a coded data block in your navigation database: the runway threshold position, the final approach course, the glidepath angle, the threshold crossing height, the alignment point, and the lateral and vertical alert limits
The block is protected by a cyclic redundancy check (CRC) so a corrupted definition is rejected rather than flown
Your navigator combines the WAAS position with the FAS data to compute where you are relative to the published lateral course and glidepath
The “shape” of the approach lives in the database; the position comes from WAAS
Why that matters in the cockpit:
You’re not tracking a ground signal — there’s nothing at the airport to tune, identify, or protect
The approach must be loaded from the database by name; you cannot build an LPV by entering waypoints, because the FAS data and the leg coding come only with the database procedure
A current database is a requirement, not a suggestion — an expired database can carry a changed glidepath angle, a moved threshold, or a revised DA
Fly it as published: correct runway, correct transition, correct sequencing
The glidepath:
A geometric path in space defined by the glidepath angle and TCH, originating at the threshold
No ground antenna, so no false glideslopes, no reflections, no bending from vehicles crossing the runway
Not derived from barometric altitude — cold air doesn’t move it
Intercept it from below like a glideslope, because that’s how the procedure is designed
Lateral Scaling: What Makes It “Localizer Performance”
The needle behavior that earns the name.
The sequence:
En route: ±2 NM full-scale (±5 NM on some older units); terminal (within 30 NM of the airport): ±1 NM
About 2 NM before the FAF: scaling steps to ±0.3 NM and the final level of service is annunciated — this is where you learn whether you have LPV
At the FAF, on LPV: scaling becomes angular and narrows continuously toward the runway, comparable to a localizer — about ±350 feet full-scale at the threshold on most units
The same geometry as an ILS localizer, computed instead of radiated
What it feels like:
Outside the FAF the needle is forgiving; inside it tightens progressively, and by short final a small drift is a visible deflection
Corrections shrink as you descend — exactly as on a localizer
Pilots who fly LPV with LNAV-sized corrections (where ±0.3 NM stays constant) will chase it on short final
Fly it like a localizer: bracket, don’t chase
Compared to the other lines:
LNAV and LNAV/VNAV: linear ±0.3 NM all the way to the runway — a half-scale deflection at the threshold is about 900 feet off centerline
LP: angular like LPV, but no vertical guidance
LPV: angular lateral plus the glidepath
“Localizer performance” is literal
Minimums
How low LPV goes:
LPV minimums can be as low as a 200-foot DA (HAT) and ½ SM visibility with the appropriate lighting — the “LPV-200” category, comparable to a CAT I ILS
Many LPVs are published at 250–350 feet because of the runway environment, obstacles, or lighting
Usually the lowest line on the plate: LPV DA < LNAV/VNAV DA < LNAV MDA (with the occasional exception where LNAV/VNAV is higher than LNAV)
Read the numbers, not the pattern
What LPV can’t do:
No CAT II or CAT III — those remain ILS (and GLS) territory
Can’t be used for alternate planning
Can’t be flown without WAAS integrity at that moment
A ceiling, not a replacement, for the ILS at the busiest airports
Comparison to the ILS on the same runway:
Where both exist, the LPV DA is frequently identical to the ILS CAT I DA
The LPV has no critical areas, no glideslope-out days, and no false glideslopes
The ILS has no WAAS-outage days and supports lower categories
Brief both; fly whichever is available and lowest
Equipment
What you need:
A WAAS-capable IFR GPS — TSO-C145 (a WAAS sensor feeding a display) or TSO-C146 (a standalone WAAS navigator); a TSO-C129 non-WAAS GPS cannot fly LPV, LP, or WAAS-vertical LNAV/VNAV
An installation approved for LPV in your aircraft (AFM supplement)
A current navigation database
A display that shows the lateral and vertical deviations and the level-of-service annunciation (CDI/HSI with glidepath, or a PFD)
What you don’t need:
A RAIM prediction — WAAS provides integrity in real time, so the preflight RAIM check required for non-WAAS GPS approaches doesn’t apply (if WAAS is NOTAMed unavailable, you’re back to RAIM-based LNAV planning)
Any ground equipment at the airport
DME, markers, or a localizer receiver
A separate glideslope receiver — the vertical deviation comes from the navigator
Autopilot:
Many autopilots couple to LPV laterally and vertically in approach mode, like an ILS; the AFM supplement for the autopilot/navigator combination says whether and how
Know the mode annunciations for a coupled LPV in your airplane
Set the altitude selector so the autopilot can’t descend below the DA on its own
Verify the capture; don’t assume
Annunciations and Downgrades
The “trust but verify” step.
The annunciations:
“LPV” — approved lateral and vertical, DA
“L/VNAV” — approved lateral and vertical, DA, linear lateral
“LP” — angular lateral, no vertical, MDA
“LNAV” — linear lateral, no vertical, MDA
“LNAV+V” / “LP+V” — advisory vertical only; still an MDA
The rule:
You may fly only the minimums that match the level of service annunciated in the final approach segment
Brief LPV; confirm “LPV” is annunciated at about 2 NM before the FAF; set the LPV DA
If the box shows L/VNAV or LNAV instead, you fly those minima — or go somewhere else
The chart publishes what the procedure supports; the receiver decides what you get
Why you might not get LPV:
WAAS integrity: the VPL exceeds the LPV alert limit (satellite geometry, ionospheric activity, a monitored satellite flagged)
A WAAS outage or degraded service (check WAAS NOTAMs in preflight)
The receiver isn’t WAAS, or the installation isn’t LPV-approved
The procedure wasn’t loaded correctly or the database is expired
Downgrade after the FAF:
If LPV service is lost after the FAF, the navigator removes the glidepath and reverts to LNAV lateral guidance
You may continue to the LNAV MDA if LNAV is annunciated and you can safely transition to the LNAV altitudes and step-downs
If you’re already below an LNAV step-down altitude, or not set up for it: go missed
Brief the downgrade plan before the FAF: “if we lose LPV inside the FAF, we continue to LNAV MDA ___ / we go missed”
Loss of integrity:
An LOI annunciation or failure to enter approach mode means the approach isn’t available — don’t start it, or go missed if you’re on it
Not a “try again” situation; it’s a different approach or a different airport
WAAS NOTAMs would usually have warned you
Check them
Flying It Well
The technique is a coupled or hand-flown ILS.
Before the FAF:
Approach loaded by name, correct runway and transition; fixes and altitudes verified against the plate; DA set; missed approach briefed
Configured and at approach speed before glidepath intercept
Approach mode active, scaling changed, “LPV” annunciated at ~2 NM prior
Cross-check the altimeter at the FAF against the published glidepath-intercept altitude — the same check you’d make at an ILS outer marker; it catches a mis-set altimeter
Intercepting the glidepath:
Be at the published intercept altitude; intercept from below
Don’t dive to catch a glidepath you’re above — that’s a sign you intercepted late or the altimeter is wrong; go around the problem (vectors, or a missed)
The glidepath comes alive as you approach the FAF; it captures like a glideslope
Configure early so the capture window is quiet
On the glidepath:
Pitch and power together — most GA SOPs use small pitch changes to hold the glidepath and power to hold airspeed; some operators do the reverse. Use your aircraft’s SOP consistently
Lateral corrections shrink as the course narrows; by the DA you’re making 1° heading changes
No chasing on either needle
Stabilized by 1,000 feet AGL in IMC
At DA:
Visual references per 91.175(c) in sight and in a position for a normal landing → continue
Not → missed approach, now — a momentary descent below DA during the go-around is expected and designed for
No leveling off at DA, no driving toward the runway: it’s a DA, not an MDA
The missed approach sequences from the MAP in the navigator — know how yours activates it
Advantages
For airports:
No localizer or glideslope transmitters to buy, site, power, or flight-check
No critical areas to protect in low weather
Vertical guidance to runways that would never have had it
A single WAAS system serves every runway in the country
For pilots:
Precision-style vertical guidance at thousands more runways
Usually the lowest minimums on the RNAV plate, often matching the ILS where both exist
No false glideslopes, no signal bending, no glideslope-out days
Angular lateral scaling you already know how to fly from the localizer
For safety:
Continuous vertical guidance replaces dive-and-drive at airports that only had nonprecision approaches
Stabilized approaches by design
Lower CFIT exposure
One of the biggest accessibility and safety upgrades in modern GA instrument flying
Limitations and Gotchas
WAAS availability:
Scheduled maintenance, satellite issues, coverage gaps at the edges of the service area, ionospheric storms, and local interference can all remove LPV
Check WAAS NOTAMs for the destination and alternate
Brief the downgrade before you need it
“Expect LPV, confirm LPV, fly what you get”
Database dependency:
An expired database can carry a changed glidepath, DA, fix, or threshold position
Verify the final approach course, fixes, runway, and minimums against the current plate every time
Load by name; never build it
The FAS data block is only as good as the cycle it came from
Temperature:
The LPV glidepath is geometric — no charted temperature limits on the path, unlike baro-VNAV
But you read the DA and fly the intermediate and missed-approach altitudes on a barometric altimeter
At cold-temperature-restricted airports (the snowflake symbol), apply the required corrections to the listed segments when the temperature is at or below the charted value, and advise ATC of corrected intermediate and missed-approach altitudes (AIM 7-2-3)
The path is immune; your altimeter isn’t
Different failure modes from the ILS:
ILS problems are local: a reflection, a critical-area incursion, a transmitter outage at that airport
LPV problems are systemic (WAAS) or in your own cockpit (receiver, database, configuration)
When an ILS fails, the airport next door is probably fine; when WAAS is down, every LPV in the region is
Plan alternates accordingly
Not for alternate planning:
You may not plan your alternate on LPV (or LNAV/VNAV) minima
Use LNAV or circling with the 800-2 standard (or published nonstandard minimums), plus the GPS/WAAS alternate rules
You can still FLY the LPV at the alternate if it’s available when you get there
Planning and flying are different questions
LPV vs. ILS vs. GLS: Where It Fits
ILS | LPV | GLS | |
Guidance source | Ground transmitters (localizer and glideslope) at the runway | GPS + WAAS (space-based augmentation) + the database FAS data | GPS + GBAS (ground station at the airport broadcasting corrections by VHF data link) |
Classification | Precision approach | APV | Precision approach |
Lowest minimums | CAT I 200 ft; CAT II/III with authorization | 200 ft (LPV-200); no CAT II/III | CAT I; CAT II/III in development |
Critical areas | Yes | No | No ILS-style critical areas |
False glidepaths | Possible (glideslope sidelobes) | No | No |
Failure modes | Local (that facility) | Systemic (WAAS) or cockpit | Local (that station) or cockpit |
Where | Major and many regional airports | Thousands of runways nationwide | A small number of major airports |
Alternate planning | 600-2 precision standard | Can’t plan on LPV; LNAV/circling at 800-2 | 600-2 precision standard |
The long view:
ILS remains the standard where CAT II/III are needed and as the GPS-independent backup
LPV is the workhorse for GA and regional IFR at everywhere else
GLS is the satellite-based precision approach for major airports as GBAS stations spread
A pilot who can fly an ILS can fly all three
Common Pilot Mistakes
Flying LPV minimums without “LPV” annunciated
Calling LPV a precision approach on the oral, or planning an alternate on LPV minima
Building the approach manually, or flying it on an expired database
Skipping the WAAS NOTAM check and discovering the downgrade at the FAF
Not briefing the downgrade plan, then improvising when the glidepath vanishes inside the FAF
Treating “+V” on an LNAV as if it were LPV
Diving to catch a glidepath from above
Chasing the angular needle on short final with LNAV-sized corrections
Leveling off at DA instead of deciding at it
Ignoring cold-temperature-airport corrections “because the glidepath is geometric”
Checkride Questions — With Answers
“What is an LPV approach?”
Localizer Performance with Vertical guidance: an RNAV (GPS) approach line with localizer-like angular lateral scaling and a WAAS-computed geometric glidepath, flown to a DA. Classified by the FAA as an approach with vertical guidance (APV), not a precision approach.
“How does WAAS make vertical guidance possible?”
Ground reference stations monitor GPS; master stations compute corrections and integrity data; geostationary satellites broadcast them. The receiver computes protection levels and offers LPV only when the vertical protection level is within the LPV alert limit (50 m; 35 m for LPV-200) — guaranteed performance or a timely alert.
“What are you following on an LPV — is there a transmitter at the airport?”
No. You’re following a computed path: the WAAS-corrected position compared against the final approach segment data block in the database (threshold, course, glidepath angle, TCH). That’s why the approach must be loaded from a current database.
“How low can LPV minimums go?”
As low as a 200-foot DA and ½ SM visibility (LPV-200) with appropriate lighting — comparable to CAT I ILS. No CAT II/III.
“What equipment do you need?”
A WAAS-capable IFR GPS (TSO-C145/C146) with an LPV-approved installation and a current database. A non-WAAS (TSO-C129) GPS cannot fly LPV. No RAIM prediction is needed with WAAS; check WAAS NOTAMs instead.
“The navigator annunciates LNAV at the FAF instead of LPV. What are your minimums?”
LNAV MDA — you may use only the minima matching the annunciated level of service.
“You lose LPV inside the FAF. What now?”
The navigator reverts to LNAV. Continue to the LNAV MDA if LNAV is annunciated and you can safely transition to its altitudes; otherwise, go missed.
“Can you plan an alternate using LPV minimums?”
No. Plan on LNAV or circling minima with the 800-2 standard (or published nonstandard), plus the GPS/WAAS alternate rules. You may still fly the LPV at the alternate if it’s available on arrival.
“Does the cold-temperature limitation apply to LPV?”
The “Baro-VNAV NA” note doesn’t — the LPV glidepath is geometric. But cold-temperature-airport (snowflake) altitude corrections still apply to the listed segments, because the DA and segment altitudes are barometric.
Final Thoughts
LPV delivers the best combination in modern IFR flying: ILS-like lateral and vertical guidance to a 200-foot DA, at thousands of runways, with no transmitter at the airport, no critical areas, and no false glideslopes. It does it by replacing the ground beam with a monitored, corrected satellite position compared against a coded procedure in your database — which is also why it demands a different discipline. The path is only as good as the WAAS integrity in that moment and the database cycle in the box.
Load it by name from a current database, check WAAS NOTAMs, confirm “LPV” before the FAF, brief the downgrade and the missed, intercept the glidepath from below, fly it like an ILS to the DA, apply cold-temperature corrections where required, and remember that it’s an APV when you plan the alternate. Do that and LPV becomes the most useful approach in your logbook.
On the Written Test and Checkride
LPV appears on the instrument knowledge test and in every instrument oral. The most commonly tested topics:
What LPV is; APV classification (AIM 5-4-5); alternate planning on LNAV/circling only
WAAS: corrections and integrity; protection levels vs. alert limits (VAL 50 m / 35 m for LPV-200); no RAIM check; WAAS NOTAMs
The FAS data block and current-database requirement
Lateral scaling: ±0.3 NM at 2 NM before the FAF, angular at the FAF (~±350 ft at the threshold)
LPV-200 minimums; no CAT II/III
Equipment: TSO-C145/C146 WAAS; C129 can’t
Annunciation rule; downgrade after the FAF
No false glidepaths, no path temperature limits; cold-temperature-airport corrections still apply
Instrument ACS: LPV with DA ≤ 300 ft HAT may serve as the precision approach task (confirm current edition)
Quick Reference
LPV — Localizer Performance with Vertical guidance:
RNAV (GPS) line: WAAS lateral (angular) + WAAS geometric glidepath → DA
APV (AIM 5-4-5), not precision; ICAO 3D, Type B if DA < 250 ft
Minimums as low as 200 ft / ½ SM (LPV-200); no CAT II/III
How It Works:
WAAS: reference stations → corrections + integrity → geostationary broadcast → receiver computes HPL/VPL; LPV offered only when VPL ≤ the LPV vertical alert limit (50 m; 35 m for LPV-200)
You follow a computed path: WAAS position vs. the FAS data block (threshold, course, glidepath angle, TCH; CRC-protected) — load by name from a current database, never build it
No ground transmitter, no critical areas, no false glidepaths
Lateral Scaling:
En route ±2 NM → terminal ±1 NM → ~2 NM before FAF: ±0.3 NM + level of service annunciated → at FAF: angular, ~±350 ft at threshold
Fly it like a localizer: bracket, shrinking corrections
Equipment:
WAAS IFR GPS: TSO-C145/C146; LPV-approved installation (AFM supplement); current database
TSO-C129 (non-WAAS) cannot fly LPV
No RAIM prediction needed; check WAAS NOTAMs
Autopilot coupling per the supplement; altitude selector at DA
Annunciation Rule:
Fly only the minima matching the final-segment annunciation: LPV → LPV DA; L/VNAV → LNAV/VNAV DA; LP / LNAV → MDA; +V = advisory, still MDA
Confirm “LPV” at ~2 NM before the FAF; set the DA
Downgrade inside the FAF → reverts to LNAV: continue to LNAV MDA if annunciated and able; else missed
LOI → not available
Flying It:
Configured before intercept; cross-check the altimeter at the FAF against the published intercept altitude
Intercept from below; never dive to catch it
Pitch/power per SOP; no chasing; stabilized by 1,000 ft AGL IMC
At DA: decide — continue with 91.175(c) references or go missed (momentary dip below DA expected); not an MDA
Limitations:
WAAS outages/ionosphere/interference → downgrade; failure modes are systemic (WAAS) or in your cockpit, not local
Expired database = wrong procedure
Path has no temperature limits, but cold-temperature-airport (snowflake) corrections still apply — the DA and segment altitudes are barometric (AIM 7-2-3); advise ATC of corrected intermediate/missed altitudes
Alternate planning: no LPV — LNAV or circling at 800-2 (TPP legend) plus GPS/WAAS rules
LPV vs. ILS vs. GLS:
ILS: ground beams, precision, CAT I–III, critical areas, local failures
LPV: WAAS, APV, 200 ft max, no critical areas, systemic failures
GLS: GBAS ground station, precision, CAT I (II/III coming), major airports
Key Principle:
LPV is an ILS-like approach computed from a WAAS-corrected position and a database-defined path: angular lateral scaling, a geometric glidepath, a DA as low as 200 feet, no transmitter and no critical areas at the airport — and an APV, not a precision approach, which matters when you plan an alternate. Load it from a current database, check WAAS NOTAMs, confirm the LPV annunciation before the FAF, brief the downgrade, intercept from below, fly it like an ILS, and correct for cold temperatures where required.
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Author: Nathan Hodell
CFI, CFII, MEI, ATP, Creator and CEO
Nathan is an aviation enthusiast with thousands of hours of flying and dual instruction over the past 15+ years. Through his aviation career he has been able to earn his ATP, fly as an airline pilot, own/operate flight schools, and create and host wifiCFI.