RNP Approaches: Essential Guidance for Flight Crews

On any given day, thousands of instrument approaches are flown to runways that lack traditional precision landing aids. Required Navigation Performance (RNP) approaches have fundamentally changed how flight crews access these runways — and increasingly, how they access all runways. With the European Commission's Implementing Regulation (EU 2018/1048) now stipulating that RNP approaches with vertical guidance must be implemented at all instrument runway ends, proficiency in these procedures is no longer optional for professional aviators. FlySafe analysis shows that understanding the operational nuances of RNP approaches — from minima selection to monitoring responsibilities — is essential for every crew operating in modern airspace.

This guide consolidates publicly available regulatory guidance, advisory circulars, and operational best practices into a single reference for flight crews transitioning to or already conducting RNP approach operations.

What Defines an RNP Approach

The distinction between Area Navigation (RNAV) and Required Navigation Performance (RNP) is precise and operationally significant. As stated by the U.S. Department of Transportation, RNP is defined as "RNAV with the addition of an onboard performance monitoring and alerting capability." That onboard monitoring and alerting capability is what separates RNP from conventional RNAV: the aircraft navigation system continuously evaluates its own accuracy and alerts the crew if the required performance level is not being met during the operation.

According to the FAA Aeronautical Information Manual (AIM), the numerical designation in any RNP specification refers to "the lateral navigation accuracy in nautical miles which is expected to be achieved at least 95 percent of the flight time by the population of aircraft operating within the airspace, route, or procedure." For example, RNP 0.3 means the aircraft is expected to remain within 0.3 nautical miles of the defined centerline at least 95 percent of the time.

This self-contained integrity monitoring is what enables reduced obstacle clearance and closer route conformance without continuous ATC intervention — a significant operational advantage in terminal environments.

Understanding the Lines of Minima: LNAV, LNAV/VNAV, LP, and LPV

RNP approach procedures — charted as "RNAV (GPS) Rwy XX" — may publish multiple lines of minima on a single chart. Each line corresponds to different equipment capabilities and provides varying levels of guidance. As of February 2016, the FAA reported over 600 LP lines of minima at 436 airports and over 6,000 LNAV lines of minima at 2,747 airports. Those numbers have grown substantially since.

LNAV (Lateral Navigation)

The baseline. LNAV provides lateral guidance only, with the pilot responsible for descent management using step-down fixes or a Continuous Descent Final Approach (CDFA) technique. The Minimum Descent Altitude (MDA) is typically the highest among the published lines of minima.

LNAV+V (Advisory Vertical Guidance)

Some avionics suites generate an advisory glide path from the final approach fix to the touchdown point. The FAA notes this is "an artificially created advisory glide path" intended "to aid the pilot in flying constant descent to the MDA." Critically, advisory vertical guidance is not a required capability and does not change the published minima — the crew still flies to LNAV MDA. The "+V" indication simply means the system is providing supplemental vertical information.

LNAV/VNAV (Lateral and Vertical Navigation)

This line of minima requires certified barometric vertical navigation (Baro-VNAV) or equivalent capability. It provides a Decision Altitude (DA) rather than an MDA, making it closer in concept to a precision approach. However, Baro-VNAV performance is affected by non-standard temperatures, which is why some LNAV/VNAV approaches carry temperature restrictions.

LPV (Localizer Performance with Vertical Guidance)

LPV represents the highest-capability line of minima for standard RNP APCH procedures. It requires Satellite-Based Augmentation System (SBAS) — WAAS in the United States, EGNOS in Europe — and provides both lateral and vertical guidance to decision altitudes that can be as low as 200 feet above threshold elevation. According to Eurocontrol, a unique SBAS channel number is required for RNP approaches to LPV or LP minima, and the function of distributing and managing these channel numbers was taken over by ICAO in 2019.

LP (Localizer Performance)

LP provides SBAS-enhanced lateral guidance without vertical guidance. It is used where terrain or obstacle environments prevent the publication of LPV minima but still allow improved lateral performance over basic LNAV.

Airspace status: Flight crews should always verify which line of minima their aircraft and avionics are approved to fly before commencing the approach. Selecting minima that exceed the aircraft's certified capability is a direct safety hazard.

RNP AR Approaches: When Authorization Is Required

Standard RNP APCH procedures (LNAV, LPV, etc.) do not require special authorization beyond the aircraft's certified PBN capability. RNP Authorization Required (AR) approaches are a different matter entirely.

Charted as "RNAV (RNP) Rwy XX," RNP AR procedures employ tighter lateral tolerances — with RNP values as low as 0.1 NM — and may include curved flight paths using Radius-to-Fix (RF) legs. According to FAA Advisory Circular 90-101A, these procedures require specific airworthiness and operational approval. The AC provides "airworthiness and operational approval guidance material for aircraft operators conducting Title 14 of the Code of Federal Regulations (14 CFR) part 97" RNP AR procedures.

The FAA AIM makes an important clarification: A-RNP eligible aircraft are NOT automatically eligible for RNP AR APCH or RNP AR DP operations. "RNP AR eligibility requires a separate determination process and special FAA authorization." This is a common source of confusion, and crews should never assume that advanced RNAV capability equates to RNP AR authorization.

Charted RNP Values

As noted in the AIM Section 1-2, charted RNP values of 0.30 or below contain two decimal places (e.g., RNP 0.15, RNP 0.10, RNP 0.30), whereas the navigation specification title states only "RNP 0.3." For RNP AR approach segments, the RNP level ranges from 0.1 to 1.0, corresponding to a primary route width (centerline to boundary) of 0.1 to 1.0 NM.

Each published line of minima on an RNP AR chart has an associated RNP value. FAA guidance states: "If the navigation system does not extract and set the RNP value from the on-board navigation database for each leg of the procedure, then the flight crew's operating procedures must ensure that the smallest RNP value required to complete the approach or the missed approach is selected before initiating the approach."

Crew Training and Recurrency Requirements

RNP approach competency does not maintain itself. Regulatory frameworks worldwide mandate specific initial and recurrent training for crews conducting these operations.

Standard RNP APCH

According to RNAV(GNSS) operational guidelines published on SKYbrary, training for RNP APCH operations must be performed "with a crew composition corresponding to the minimum requirement set by the operator or the flight manual." The minimum training comprises both a theoretical and a practical component, each dispensed in accordance with a programme approved by the authority. The head of the training organisation must certify complete and satisfactory performance by each pilot.

Importantly, RNAV(GNSS) approaches must be included in recurrent training and checking programmes "with the same requirements as those concerning conventional non-precision approaches." Operators are also required to define risks and threats linked to the procedure, including factors such as barometric error, temperature effects, and equipment deterioration.

RNP AR APCH

The recurrent training bar is higher for RNP AR operations. The FAA RNP AR Application Guide specifies that each pilot must complete at least two RNP AR APCH procedures as part of recurrent training — one as pilot flying and one as pilot monitoring. Of these two approaches, one must be flown to the Decision Altitude (DA), and one must result in an RNP missed approach procedure. This ensures that crews maintain proficiency in both the successful completion and the discontinuation of RNP AR approaches.

Monitoring, Alerting, and the Go-Around Decision

The onboard performance monitoring system is the backbone of RNP operations. The U.S. DOT notes that this capability "enhances the pilot's situational awareness and can enable reduced obstacle clearance or closer route conformance without intervention by air traffic control." But the system is only as effective as the crew's response to its outputs.

Coupling Requirements

For RNP AR approaches, the flight crew must be able to couple the autopilot or flight director to the RNP system (engage LNAV) by 400 feet AGL. This is a hard requirement, not a recommendation. Operating below this altitude without proper lateral guidance coupling on an RNP AR procedure is outside the approved operational envelope.

Alert Response

When a loss of navigation capability or loss of RNP containment integrity occurs, the RNP AR Application Guide states that an aural alert "should accompany the visual alert" within the flight crew's primary field of view. The crew response to such an alert is unambiguous: initiate the published missed approach procedure.

GNSS Loss and Automatic Reversion

A critical system requirement addresses GNSS failure during the approach. The aircraft must be able to "automatically revert to another means of navigation that complies with the RNP value after initiating a go-around or missed approach following loss of GNSS." Flight crews must understand their specific aircraft's reversion logic and verify during preflight that alternative navigation sources are available and functional.

Recommendation: Crews should brief the specific RNP alert annunciations for their aircraft type, the required response, and the missed approach procedure — including the navigation source reversion — before every RNP approach.

Operational Considerations for Barometric Vertical Navigation

It is the pilot's responsibility to use the current barometric altimeter setting to ensure compliance with altitude restrictions for all approach operations. This responsibility carries additional weight on LNAV/VNAV approaches, where the vertical path is generated by the aircraft's Baro-VNAV system based on atmospheric pressure data.

Temperature deviations from ISA can cause significant errors in barometric altitude computation. In extreme cold, the actual altitude of the aircraft will be lower than the indicated altitude, potentially reducing obstacle clearance below safe margins. This is why some LNAV/VNAV approaches publish temperature limitations, and why crews operating in cold-weather environments must apply temperature corrections per their operator's approved procedures or the applicable regulatory guidance.

The Expanding Role of RNP in Global Airspace

The trajectory of RNP implementation is clear. RNAV and RNP capabilities "facilitate more efficient design of airspace and procedures which collectively result in improved safety, access, capacity, predictability, and operational efficiency, as well as reduced environmental impacts," according to the U.S. DOT. The European regulatory mandate for RNP approaches at all instrument runway ends further accelerates adoption.

Affected routes: Virtually every IFR operation in controlled airspace will increasingly rely on PBN procedures. Crews who have not invested in thorough understanding of RNP approach categories, their aircraft's specific capabilities, and the associated monitoring requirements face a widening competency gap.

The FAA has also explored extending RNP concepts into the visual segment, developing procedures that provide "continuous lateral and vertical guidance from the procedure's initial approach fix to the runway" — including named waypoints and recommended altitudes in the visual segment. This evolution suggests that the boundary between instrument and visual segments may continue to narrow.

Key Takeaway

Based on publicly available NOTAMs and regulatory publications, RNP approach operations demand more from flight crews than traditional non-precision approaches — not less. The automation provides tighter guidance and lower minima, but it requires precise knowledge of equipment capabilities, correct minima selection, disciplined monitoring, and trained responses to system alerts. FlySafe analysis shows that the crews best prepared for RNP operations are those who treat these procedures with the same rigor as Category II/III ILS operations: thorough briefing, clear task division, and unambiguous go-around criteria.

Airlines have rerouted training programmes and operational approvals around PBN procedures, and the regulatory trend is toward mandatory RNP capability at more airports worldwide. For flight crews, the time to build deep competency in RNP approaches is not approaching — it has arrived.

Analysis based on publicly available data only. FlySafe provides aviation risk intelligence derived exclusively from published regulatory sources, NOTAMs, and open-data projects.

Frequently Asked Questions

What is the difference between LNAV+V, LNAV/VNAV, and LPV approaches?

LNAV+V provides lateral guidance with an uncertified advisory glide path — the crew still flies to MDA, not a decision altitude. LNAV/VNAV uses certified Baro-VNAV to provide both lateral and vertical guidance to a DA but is subject to temperature limitations. LPV uses SBAS (WAAS/EGNOS) for the most precise lateral and vertical guidance, enabling decision altitudes as low as 200 feet, comparable to a Category I ILS.

Do I need special authorization and training to fly RNP AR approaches?

Yes. RNP AR procedures (charted as "RNAV (RNP) Rwy XX") require a separate airworthiness determination and special FAA authorization per AC 90-101A. Standard A-RNP capability does not confer RNP AR eligibility. Recurrent training requires a minimum of two RNP AR approaches — one flown to DA and one resulting in a missed approach — for each pilot.

What must my aircraft automatically do if it loses GPS signal during an RNP approach?

The aircraft must be capable of automatically reverting to another means of navigation that complies with the required RNP value after the crew initiates a go-around or missed approach following GNSS loss. The specific reversion logic varies by aircraft type and should be verified during preflight preparation.

Why are some LNAV/VNAV approaches restricted in extreme hot or cold weather?

LNAV/VNAV vertical guidance relies on barometric altitude computation, which is affected by non-standard temperatures. In extreme cold, actual aircraft altitude is lower than indicated altitude, reducing obstacle clearance. Temperature restrictions on these approaches protect against this error margin when Baro-VNAV corrections cannot guarantee safe terrain separation.

How many satellites are required for RNP approaches when using barometric aiding?

The specific satellite count depends on the avionics suite and receiver type, but the operational requirement is that the navigation system must achieve and maintain the published RNP value with integrity monitoring throughout the procedure. If the system cannot maintain the required performance — regardless of satellite count — it must alert the crew, who are then required to execute the missed approach.