Comparing LPV and ILS

A rriving at your destination on a dreary day, ATC queries you with say approach requested. The landing runway has an ILS and an RNAV (GPS) approach with identical LPV minimums published. Which do you choose? You would be forgiven for thinking, as we initially did, that this is a bit of an inconsequential question. WAAS has enabled satellite guided approaches to have precision comparable to Category I ILS approaches, so what difference does it make? Although true, this doesnt mean that ILS and LPV are identical in all regards.

IFR Staff

Monday, June 03, 2019 at 12:00 AM ET

Verified

Key Takeaways:

While both ILS and LPV approaches offer comparable precision for landing (often with 200ft decision height) and similar flight paths, ILS relies on local ground infrastructure prone to maintenance and localized interference, whereas LPV utilizes satellite-based WAAS, which avoids local infrastructure costs but is susceptible to wider GPS jamming or space weather.
Operationally, LPV is classified as an "Approach with Vertical Guidance" (APV) rather than a "Precision Approach" like ILS, impacting alternate airport planning minimums (LPV requires a higher ceiling). Additionally, missed approach procedures can differ significantly between the two, and ILS can have false glideslope indications absent in LPV.
Pilots should consider factors like alternate planning requirements, potentially differing minimums or missed approach procedures, comfort with specific avionics (e.g., ILS tuning), and current system availability (e.g., GPS jamming NOTAMs or ILS critical area restrictions) when choosing between an ILS and LPV approach.

See a mistake? Contact us.

Arriving at your destination on a dreary day, ATC queries you with “say approach requested.” The landing runway has an ILS and an RNAV (GPS) approach with identical LPV minimums published. Which do you choose? You would be forgiven for thinking, as we initially did, that this is a bit of an inconsequential question. WAAS has enabled satellite guided approaches to have precision comparable to Category I ILS approaches, so what difference does it make? Although true, this doesn’t mean that ILS and LPV are identical in all regards.

ILS approaches have been around and largely unchanged since the 1930s. WAAS became operational in 2003, and the first GPS approaches with LPV minimums were introduced in September of that year. Since then there have been 3998 approaches with LPV minimums published, whereas there are currently 1549 Category I ILS approaches published. GPS approaches with LPV minimums seem to be showing up everywhere these days, mainly because there is no need to build and maintain costly infrastructure at each airport to support them, as is the case for ILS.