Draft AC 90-119 Performance-Based Navigation Operations

An important new Advisory Circular 90-119 Performance-Based Navigation Operations was released for comment in May 2021 and is now in the review and coordination phase at FAA. You can find the draft PDF in my Aviation Documents folder here. FAA has not announced when the final AC will be published, but if past review cycles are a guide, it may appear by the end of 2022 or early 2023.

You can read my detailed initial comments to FAA here (PDF).

This advisory circular (AC) replaces and consolidates several ACs…and provides guidance for operators using Performance-based Navigation (PBN) in the United States, in oceanic and remote continental airspace, and in foreign countries that adopt International Civil Aviation Organization (ICAO) PBN standards.

The draft AC includes updates to FAA policy in some key areas, and it will replace several existing guidance documents, including:

  • AC 90-100A CHG 2, U.S. Terminal and En Route Area Navigation (RNAV) Operations, dated April 14, 2015;
  • AC 90-105A, Approval Guidance for RNP Operations and Barometric Vertical Navigation in the U.S. National Airspace System and in Oceanic and Remote Continental Airspace, dated March 7, 2016;
  • AC 90-107, Guidance for Localizer Performance with Vertical Guidance and Localizer Performance without Vertical Guidance Approach Operations in the U.S. National Airspace System, dated February 11, 2011; and
  • AC 90-108 CHG 1, Use of Suitable Area Navigation (RNAV) Systems on Conventional Routes and Procedures, dated April 21, 2015.

The language in this AC also affects sections of the AIM; FAA handbooks such as the Instrument Flying Handbook and Instrument Procedures Handbook; and Airmen Certification Standards that include instrument tasks.

Key Updates

Here are some of the key updates to FAA guidance and policy in the new AC. Detailed discussion of each item follows.

  • Use of suitable RNAV systems on conventional routes and procedures, which clarifies how you can use an IFR-approved GPS on all types of IFR procedures, including those that use localizer courses, until you reach the final approach segment.
  • Expanded definition and clarification of the term RNP APCH, which many pilots confuse with RNP AR APCH. FAA adds RNP APCH notes to approaches with RNAV (GPS) in the title and does not plan to adopt current ICAO conventions for naming PBN procedures (for background, see this post here at BruceAir). More details on this topic appear below.
  • Updated definition of precision approach, which now explicitly includes all RNAV (GPS) approaches with LPV minimums. The AC also aligns FAA terminology with the ICAO definitions for procedures that include 2D (lateral navigation) and 3D (lateral and vertical navigation).

Use of Suitable RNAV Systems on Conventional Routes and Procedures

For general aviation pilots who use IFR-approved GPS and WAAS avionics, the draft AC clarifies a key issue, the use of RNAV (i.e., GPS and WAAS) while flying routes and procedures based on navaids. In particular, Chapter 11 describes specific situations in which pilots can use RNAV as an alternate means of navigation or as a substitute for navaids, and the document clarifies when you can use GPS to navigate along localizer courses outside the final approach segment.

(I recently gave a webinar for the American Bonanza Society on this topic. You can watch that presentation here and read more about the topic here.)

The draft AC provides the following updated definitions:

11.1.1.1 Alternate Means of Navigation. The pilot’s use of a suitable RNAV system to navigate on a conventional route or procedure without monitoring the operational NAVAID(s) defining the route or procedure. “Alternate means” applies to a situation where the pilot has options or a choice, and uses the suitable RNAV system primarily for convenience.

11.1.1.2 Substitute Means of Navigation. The pilot’s use of a suitable RNAV system to navigate on a conventional route or procedure in an aircraft with inoperative or not-installed conventional navigation equipment and/or when conventional NAVAIDs are out of service. “Substitution” applies to a situation where the NAVAID or the aircraft equipment are inoperative or unavailable (i.e., the pilot cannot use or monitor the conventional NAVAID).

11.1.1.3 Suitable RNAV System. Per § 1.1, an RNAV system is suitable when it (1) is installed for IFR operations, and (2) meets the navigation performance criteria required by ATC for the route or procedure to be flown. Put simply, suitable RNAV systems are those that meet the criteria identified in this AC for RNAV operations.

Section 11.4.2 Authorized Uses of Suitable RNAV Systems describes specific situations in which you can use GPS to complement or substitute for ground-based navaids.

The most significant update is item 6 (reinforced by paragraph 11.4.3.3), which clarifies that you can use GPS to navigate all legs of any conventional approach procedure, including procedures based on a localizer, until you reach final approach segment:

1. Determine aircraft position relative to, or distance from, a conventional NAVAID, DME fix, or named fix based on a conventional NAVAID.

2. Navigate to or from any conventional NAVAID or fix, via direct or a defined course.

3. Hold over any conventional NAVAID or DME fix.

4. Fly a published arc based upon DME.

5. Fly a route, comprised of charted airways, fixes, and/or NAVAIDs.

6. Navigate to the FAS of a conventional IAP.

7. Navigate the lateral course of the FAS on an IAP based on a VOR, Tactical Air Navigation System (TACAN), or Non-Directional Beacon (NDB) signal. The aircraft equipment and underlying NAVAID must be operational and monitored for FAS course alignment. The underlying NAVAID remains the primary source of navigation for the FAS course and should be used for course alignment if the RNAV system track differs from the underlying NAVAID course.

Items 1-2 also mean that you can use RNAV to fly departures and arrivals based on conventional navaids.

Item 6 is backed up by additional paragraphs:

11.4.3.1 On Unusable or Not Authorized (NA) Procedures. Pilots may not fly any portion of a conventional route or procedure identified (by chart annotation or NOTAM) as unusable or not authorized (“NA”).

Note: Pilots should take particular care when loading routes by name or title, especially routes defined solely by conventional NAVAIDs. Conventional routes designated as “unusable” by chart notation or NOTAM are unusable by any user. Pilots should not file for, and ATC should not use, the unusable route title or name in the IFR clearance. This does not preclude the use of direct clearances to usable waypoints along or across a charted route designated as “unusable.” [For more background on this issue, see Unusable Airways, Routes, and Segments here at BruceAir.]

11.4.3.2 As Sole Means of Navigation on Conventional FAS. Pilots may not use RNAV as the sole means of navigation to fly the final approach course on a conventional instrument approach.

11.4.3.3 To Navigate a Localizer (LOC) Final Approach Course. Pilots may not use RNAV to fly a FAS defined by an LOC signal.

Together, these sections mean that you can use an IFR-approved GPS to fly departures; airways; arrivals; feeder routes; track a VOR radial or localizer course to a course reversal or HILPT; fly DME arcs; fly holds, including holds based on DME fixes; and to fly the legs of missed approach procedures based on navaids, including localizers.

Paragraph 11.4.3.2 As Sole Means of Navigation on Conventional FAS emphasizes that you cannot use GPS for lateral guidance along the final approach segment of a VOR or NDB approach unless the navaid is operational and you can monitor the course on a bearing pointer or CDI. This paragraph aligns with previous guidance in the AIM and AFM supplements, as I’ve noted in several posts here at BruceAir.

RNP APCH

Paragraph 12.3 RNP APCH Overview provides background on the use of the note RNP APCH, which now appears on many charts.

This note is one way that FAA attempts to align its naming conventions for PBN approaches with updated ICAO standards (for background, see FAA InFO16020). As the AC explains:

In the United States, RNP APCH applies to all approach applications based on Global Positioning System (GPS), normally titled “RNAV (GPS)” or with “or GPS” in the title. These procedures provide operators one or more lines of minima (i.e., LNAV, LNAV/VNAV, LPV, or LP)…The RNP APCH NavSpec is intended to encompass all segments of the terminal approach operation: initial, intermediate, final, and missed approach…Charts for RNP APCH procedures will prominently display a standardized PBN Notes Box containing the procedure’s requirements including NavSpec(s) and, if needed, any required sensors or additional functionality (e.g., RF capability), as well as any minimum RNP value required for the procedure, and applicable remarks.

In other words, in the U.S., GPS-based approaches are titled RNAV (GPS) RWY xx. These approaches also include a RNP APCH note to confirm that they require the equipment needed to fly to the RNP terminal and final approach standards (i.e., RNP 1 and RNP 0.3 for LNAV minimums to an MDA or LPV, LNAV/VNAV to a DA, or LP standards for lateral guidance to an MDA).

RNP APCH is not the same as the authorization required to comply with the RNP AR APCH standard. In the U.S. approaches that require the RNP AR APCH standard are titled RNAV (RNP) RWY xx.

As the draft AC notes:

This AC does not apply to Required Navigation Performance Authorization Required Approach (RNP AR APCH) approaches, titled “RNAV (RNP)” (ICAO: RNP RWY xx (AR)). Guidance for RNP AR operations is in AC 90-101( ), Approval Guidance for RNP Procedures with AR.

Definition of Precision Approach

The draft AC updates the definition of precision approach, which now explicitly includes all RNAV (GPS) approaches with LPV minimums. The AC also aligns FAA terminology with the ICAO definitions for procedures that include 2D (lateral navigation) and 3D (lateral and vertical navigation).

In the past, precision approach applied only to procedures based on ground facilities that provide a glideslope or other approved vertical guidance to a DA–viz., an ILS or PAR. That obsolete definition required the creation of a new term, APV (approaches with vertical guidance), for RNAV procedures that offer approved vertical guidance to LPV or LNAV/VNAV decision altitude minimums.

Today, ICAO has updated its definition of precision approach by describing procedures that include approved vertical guidance to a DA, so-called 3D navigation. ICAO also describes so-called 2D approaches to MDAs.

With that change in mind, the new AC explains precision approaches (PA) and nonprecision approaches (NPA) that use GPS:

12.3.1.1 NPA Operations. These two-dimensional (2D) operations use GPS-derived lateral guidance from the RNP system. The procedure provides obstruction clearance as long as the pilots strictly adhere to the published minimum altitudes along the approach course, primarily by reference to the barometric altimeter. These 2D procedures typically have LNAV lines of minima to a minimum descent altitude (MDA).

12.3.1.2 PA Operations. These 3D operations use either ground-based, GPS-derived, and/or integrated electronic vertical guidance from the RNP system to enable lateral and vertical navigation to decision altitude (DA)/decision heights (DH) at or below 250 feet above ground level (AGL) (depending on the presence of obstacles). Typically, these are shown as LPV or LNAV/VNAV (and ILS/GLS) DA/DHs.

This section of the AC also notes that:

Note 2: Some approach procedures that contain both precision and nonprecision features are internationally designated as “Approaches with Vertical Guidance (APV).” These 3D approach procedures use GPS or SBAS to generate integrated electronic vertical and lateral guidance from the RNP system. These procedures typically have LNAV/VNAV lines of minima to DA/DH as low as 251 feet AGL. In the United States, all procedures to a LPV DA (regardless of height above touchdown (HAT)) are considered 3D precision operations. [Emphasis added]

This change should help reduce confusion about when IFR students and applicants for instrument ratings can use RNAV (GPS) approaches with LPV minimums to accomplish requirements for practicing and demonstrating precision approaches on practical tests.

Other Sections

The AC includes updated guidance in several other areas, beyond technical requirements for approval and use of RNAV systems.

For example, paragraph 3.6.7.4 Extract Procedures by Name notes that:

Pilots should extract PBN procedures by name from the onboard navigation database and ensure the extracted procedures match the charted procedures.

Note 1: Pilots operating aircraft with some early-model legacy RNAV navigators may not be able to extract certain PBN departure and arrival procedures by name from the navigation database. In these aircraft, pilots may load the departure or arrival procedures by extracting the individual fixes defining the procedures from the navigation database and loading them into the flight plan for their aircraft’s RNAV system. When this is necessary, pilots should confirm the resulting flight plan content matches the charted PBN procedure.

Note 2: Pilots are also cautioned that some procedures, even if extracted by name from the database, may not contain every segment, turn point, or conditional waypoint, or may contain “computer navigation fixes (CNF)” not shown on the procedure. It is always the pilot’s responsibility to ensure the aircraft’s flightpath conforms to the ATC clearance.

Paragraph 3.6.7.5 Extract PBN Routes in Their Entirety cautions that:

Pilots should extract the PBN routes from the navigation database whenever possible rather than loading the route by stringing individual fixes defining the route in sequence.

Note 1: This does not preclude a pilot’s use of a legacy RNAV navigator that cannot auto-load a PBN route into the navigator’s flight plan. A pilot may load a PBN route by extracting the individual fixes defining the route from the onboard navigation database and loading into the flight plan, fix by fix. When this is necessary, pilots should confirm the resulting flight plan route entries match the charted routes.

Note 2: Caution is warranted when loading routes into the RNAV system for convenience, especially conventional routes defined by ground NAVAIDs. Routes designated as “unusable” by chart notation or NOTAM are unusable by any user. Pilots should not file for, and ATC should not use, the unusable route title or name in the IFR clearance. This does not preclude the use of “direct to” clearances to usable waypoints along a charted route designated as “unusable.”

Paragraph 3.6.7.6 Creating or Altering Waypoints also warns that:

For any published (i.e., charted) PBN routes or procedures, pilots may only use waypoints downloaded from the aircraft navigation database. Pilots may not create waypoints (e.g., by using latitude/longitude coordinates, place/bearing, or any other means) for use on published PBN routes or procedures. Pilots also may not change any parameters of waypoints downloaded from the navigation database (e.g., changing a flyover waypoint to a flyby waypoint).

Paragraph 3.6.7.7 Cross-Check Flight Plan Against ATC Clearance recommends that:

Pilots should cross-check the navigation system’s flight plan against their ATC clearance and the charted routes and procedures. Both the flight plan’s textual display and the aircraft’s electronic moving map display (when available) can aid in this cross-check. When required by NOTAM or by the aircraft’s operating manual and SOP, pilots should confirm exclusion of specific ground-based navigation aids. If at any time during these cross-checks, a pilot doubts the validity of the route or procedure they extracted from the navigation database, they should not attempt to execute the route or procedure.

Note: Pilots may notice a slight difference between the navigation information portrayed on the chart and their primary navigation display. Differences of up to 5 degrees may result from avionics’ application of magnetic variation. These differences are acceptable.

Paragraph 3.6.10 and others in that section explain equipment required notes on PBN procedures. I won’t repeat all those details here. You can find background at Equipment Required Notes on IFR Procedure Charts here at BruceAir. I’ll update that post when I can distill the current FAA guidance as described in the new AC.

Finally, section 3.7 Training offers detailed guidance on the steps pilots should take to ensure that they understand how to use RNAV systems. A list appears in paragraph 3.7.3. Many of these items are also covered in existing industry guidance, such as the free Garmin GTN 750 Sample Training Syllabus (PDF).

Latest on VOR Decommissioning

Here’s the latest information about the FAA program to decommission about 34 percent (307) of the VOR navaids in the U.S. by fiscal year 2030, leaving 589 VORs in the system. That plan includes establishing a minimum operational network (MON) of navaids and airports. The details are in an update (PDF) delivered at the April 26-29, 2021 session of the Aeronautical Charting Meeting.

You can find more information about the FAA plan in previous updates here at BruceAir:

You can also watch video of an FAA webinar about the MON program on YouTube:

Here’s a summary of the next sets of VORs to be shut down. To see the VOR locations on aeronautical charts at SkyVector.com, click the navaid ID links.

Discontinue six (6) VORs – June 17, 2021:

  1. (HNN) Henderson, WV
  2. (LEB) Lebanon, NH
  3. (LWM) Lawrence, MA
  4. (MSS) Massena, NY
  5. (MWA) Marion, IL
  6. (SLK) Saranac Lake, NY

Discontinue six (6) VORs – August 12, 2021:

  1. (DCU) Decatur, AL
  2. (GBG) Galesburg, IL
  3. (MAP) Maples, MO
  4. (STS) Santa Rosa, CA
  5. (UCA) Utica, NY
  6. (VQQ) Jacksonville, FL

Discontinue five (5) VORs – October 7, 2021:

  1. (EEN) Keene, NH
  2. (HUL) Houlton, ME
  3. (MCM) Macon, MO
  4. (PSM) Portsmouth, NH
  5. (RFD) Rockford, IL

FAA also plans to expand the service volumes of the remaining VORs and DMEs to support the MON.

FAA Releases List of VORs to be Shut Down

FAA has published a list of 308 VORs that it plans to shut down in phases by 2025. The notice in the Federal Register appeared on July 26, 2016. The notice includes a list of VORs that the FAA wants to decommission.

This document provides the discontinuance selection criteria and candidate list of VOR Navigational Aids (NAVAIDs) targeted for discontinuance as part of the VOR MON Implementation Program and United States (U.S.) National Airspace System (NAS) Efficient Streamline Services Initiative. Additionally, this policy addresses the regulatory processes the FAA plans to follow to discontinue VORs.

For background on the FAA’s plans, see Latest Info on VOR Shutdowns here at BruceAir. Note that under this plan, only about one-third of the existing network of VORs will be decommissioned.

According to the FAA notice:

The following criteria were used by the FAA to determine which VORs would be retained as a part of the MON:

— Retain VORs to perform Instrument Landing System (ILS), Localizer (LOC), or VOR approaches supporting MON airports at suitable destinations within 100 NM of any location within the CONUS. Selected approaches would not require Automatic Direction Finder (ADF), Distance Measuring Equipment (DME), Radar, or GPS.Show citation box

— Retain VORs to support international oceanic arrival routes.

— Retain VORs to provide coverage at and above 5,000 ft AGL.

— Retain most VORs in the Western U.S. Mountainous Area (WUSMA), specifically those anchoring Victor airways through high elevation terrain.

— Retain VORs required for military use.

— VORs outside of the CONUS were not considered for discontinuance under the VOR MON Implementation Program.

The following considerations were used to supplement the VOR MON criteria above:

— Only FAA owned/operated VORs were considered for discontinuance.

— Co-located DME and Tactical Air Navigation (TACAN) systems will generally be retained when the VOR service is terminated.

— Co-located communication services relocated or reconfigured to continue transmitting their services.

According to the FAA notice:

The FAA remains committed to the plan to retain an optimized network of VOR NAVAIDs. The MON will enable pilots to revert from Performance Based Navigation (PBN) to conventional navigation for approach, terminal and en route operations in the event of a GPS outage…

The VOR MON is designed to enable aircraft, having lost Global Navigation Satellite System (GNSS) service, to revert to conventional navigation procedures. The VOR MON is further designed to allow aircraft to proceed to a MON airport where an ILS or VOR approach procedure can be flown without the necessity of GPS, DME, ADF, or Surveillance. Of course, any airport with a suitable instrument approach may be used for landing, but the VOR MON assures that at least one airport will be within 100 NM.

Updated AC 90-105A

FAA has published AC 90-105A – Approval Guidance for RNP Operations and Barometric Vertical Navigation in the U.S. National Airspace System and in Oceanic and Remote Continental Airspace (PDF available at the link).

AC90-105A

 

This update to the previous edition (published in 2009) contains many important changes for pilots who use GPS to navigate under IFR.

FAA is gradually adopting the concept of performance based navigation (PBN), which includes the old systems of area navigation (RNAV) and refines details of required navigation performance (RNP). For more details about these standards, see AIM Section 2. Performance−Based Navigation (PBN) and Area Navigation (RNAV).

Latest Update on VOR Decommissioning Program

The latest update from FAA on its plans to decommission VORs includes the following details:

  • Decommission approximately 30% (308) of the current 957 VORs by 2025
  • 74 VORs will be shut down during phase 1 (FY2016 through FY2020)
  • Another 234 VORs will be decommissioned during phase 2 (FY2021 – FY2025)
  • Of the 308 VORs to be shut down, 15 will be in the West, 162 in the central U.S., and 131 in the East.
  • 649 VORs will remain in operation after 2025, forming the minimum operational network (MON).

The goals established for the MON include allowing pilots to:

  • Revert from PBN to conventional navigation in the event of a Global Positioning System (GPS) outage;
  • Tune and identify a VOR at an altitude of 5,000 feet or higher;
  • Navigate using VOR procedures through a GPS outage area;
  • Navigate to a MON airport within 100 nautical miles to fly an Instrument Landing System (ILS) or VOR instrument approach without Distance Measuring Equipment (DME), Automatic Direction Finder (ADF), surveillance, or GPS; and
  • Navigate along VOR Airways especially in mountainous terrain where surveillance services are not available and Minimum En Route Altitudes (MEAs) offer lower altitude selection for options in icing conditions.

Progress will be slow initially. Only 5 VORs are to be shut down by September 2016. Another 4 navaids will be decommissioned by September 2017, followed by 4 more through September 2018. In 2019, FAA plans to shut down an additional 25 VORs, followed by 36 more in 2020.

Phase 2 begins in FY2021. A total of 234 VORs will be shut down through 2025.

You can read more details about the MON plan in the minutes of the 15-02 meeting of the Aeronautical Charting Forum.

 

Update on VOR Decommissioning

The Aeronautical Charting Forum, a forum sponsored by FAA, met on April 29, 2014 outside Washington, DC. Among the items on the agenda was an update on FAA’s plans to reduce the number of VORs to a minimum operational network (MON). You can download and review a PDF version of the FAA’s PowerPoint presentation here. (Minutes from the full two-day meeting are available here.)

Key points:

  • FAA now plans to transition from a legacy network of 967 VORs to a MON of  approximately 500 VORs by FY2025. That’s a slip of five years from the previous goal of establishing the MON by 2020. For more background, see the FAA’s VOR Minimum Operational Network (MON) Information Paper (PDF).
  • The number of VORs comprising the MON may increase or decrease depending on the requirements for the Department of Defense and the Tactical Operations Committee.

You can find additional details about the FAA’s program to decommission VORs here at BruceAir’s blog: