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 ILS and LPV approaches offer similar precision and minimums, LPV (WAAS-enabled GPS) is rapidly expanding due to its reliance on satellite infrastructure, eliminating the need for costly ground-based equipment required by ILS.
Key differences include potentially varied missed approach procedures, distinct sensitivities to interference (local obstacles for ILS vs. GPS jamming/space weather for LPV), and differing operational classifications that affect alternate airport planning minimums (ILS is "precision," LPV is "APV").
Pilots should consider factors like specific minimums, missed approach design, potential outages or interference affecting each system, and operational classifications when choosing between ILS and LPV for an approach.

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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.