LPV vs ILS: Compare Guidance, Minima, Equipment and Failure Modes
LPV and ILS can present similar cockpit guidance, but their classification, infrastructure, equipment requirements, alternate rules and failure modes are different.
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Updated July 16, 2026
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LPV and ILS both provide lateral and vertical guidance, and a pilot may fly them with similar control inputs. That cockpit resemblance does not make the systems interchangeable.
The current chart, NOTAMs, avionics approvals, aircraft flight-manual supplements and displayed equipment status control a real operation. This comparison is a planning framework, not a substitute for those sources or for instrument instruction.
The classification difference matters
The FAA classifies an LPV line of minima as an approach with vertical guidance, or APV, rather than a precision approach. LPV uses GPS position corrected by the Wide Area Augmentation System and presents angular lateral and vertical guidance.
An ILS is a ground-based precision-approach system. Its localizer provides lateral guidance and its glideslope provides vertical guidance. The FAA identifies ILS as the system currently approved for Category II and III operations.
Some published LPV decision altitudes can be as low as 200 feet above touchdown when the procedure and supporting system meet the requirements. That is not a universal LPV minimum and it does not change the FAA classification. The published line of minima on the current procedure is the one that matters.
Compare the complete operating chain
| Question | LPV | ILS |
|---|---|---|
| Guidance source | GPS with WAAS corrections | Airport localizer and glideslope transmitters |
| FAA approach class | APV | Precision approach |
| Aircraft equipment | Approved WAAS-capable navigation installation and current database | Compatible localizer/glideslope receiver and installation |
| Ground infrastructure at runway | Does not require localizer and glideslope transmitters | Requires installed, monitored ground facilities |
| Lowest available category | Procedure-specific LPV minima; not Category II or III | Category I, II or III where the complete operation is approved |
| Main dependency | Satellite/WAAS service, database, approved installation and annunciated integrity | Facility status, receiver, signal coverage and monitored ground equipment |
The table does not decide which line a pilot may use. Confirm the equipment, authorisations and procedure notes for the aircraft and operation.
Equipment capability is installation-specific
"GPS equipped" does not establish LPV capability. The navigator, antenna, software, database, indicators and installation approval all matter. The flight-manual supplement should describe approved operations, limitations, annunciations and responses to loss of integrity or service.
ILS capability also depends on more than a frequency window. The installation must provide the required localizer and glideslope indications, and the pilot must account for facility status, identification, procedure notes and any operational authorisation needed for the category flown.
When comparing a panel upgrade, ask the installer to identify the exact approach capabilities after installation, the approval basis, the annunciations the pilot will see and how guidance is coupled to any autopilot.
The failure modes are different
An LPV-capable receiver continuously determines the level of service available. A loss or change in WAAS integrity can prevent LPV activation, produce a downgrade before the final segment or make the approach unavailable. The correct response depends on timing, the annunciation, the approved equipment guidance and whether another published line of minima remains usable.
ILS can be affected by a reported facility outage, failed or unmonitored component, receiver problem, signal interference or an aircraft-system fault. Because the guidance comes from separate ground infrastructure, it can remain an independent option when satellite navigation is disrupted. That does not make every ILS available: check facility status and NOTAMs.
Plan the missed approach and diversion around system diversity that actually exists in the aircraft and at the destination, not around two approach names that look similar on a chart.
Alternate planning is not an arrival shortcut
FAA guidance places specific conditions on using WAAS-based procedures for alternate-airport planning. A pilot should not select an alternate merely because its lowest LPV minima look acceptable. The current AIM, 14 CFR 91.169, the available nonprecision or circling minima and the aircraft's approved navigation capability must be applied to the plan.
The level of WAAS service available on arrival may allow a higher-capability line of minima to be flown, but that does not rewrite the planning basis used when the flight was filed. Keep the planning rule and the service actually available at arrival as two separate decisions.
A practical comparison before departure
For each approach that could matter, record:
- the current procedure revision and applicable notes;
- the line of minima the aircraft and crew are authorised and equipped to use;
- NOTAM and facility or service status;
- the required onboard indications before continuing;
- the response to a downgrade or lost component;
- the missed-approach navigation requirement; and
- an alternative that does not share the same critical dependency.
LPV has extended vertically guided access to many runways without ILS infrastructure. FAA WAAS figures current to 2025 list 4,219 LPV procedures at 2,035 airports, including 1,273 airports without ILS. ILS remains operationally important because it uses different infrastructure and supports approach categories LPV does not.
The useful distinction is therefore not "new versus old." It is which approved guidance, minima and independent failure paths are available for this aircraft, runway and flight.
