An RNAV Approach in VMC

In this video, I depart Jefferson County International Airport (0S9) on the Olympic Peninsula and fly the RNAV RWY 20 approach at Bremerton (KPWT) in visual conditions.

This is an exercise I do with my instrument students as they begin flying approaches. It’s useful to observe several approaches, preferably with the autopilot engaged, to help new IFR pilots correlate what they see out the window with the navigation displays, aircraft attitude, power settings, and configurations used during an IFR approach. Watching the autopilot fly the approach helps students clearly see the subtle corrections needed to track courses and glidepaths. And observing the proximity to terrain and obstacles reinforces the need to fly the published courses and altitudes precisely.

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An ILS that Requires GPS

You can still fly IFR in the U.S. without an IFR-approved GNSS (i.e., GPS), but being “slant G” (/G in the soon-to-be obsolete FAA domestic flight plan format) increasingly offers advantages, even if you fly only conventional procedures based on ground navaids. And sometimes an IFR-approved GNSS is required to fly even an ILS.

Another example is the ILS or LOC RWY 28R at Billings, MT (KBIL)

Consider the ILS Z OR LOC Z RWY 16R approach at Reno/Tahoe International Airport (KRNO). This procedure is not an Authorization Required approach–RNP doesn’t appear in the title, and you won’t find that restrictive note on the chart.

For more information about RNP procedures, see RNP Procedures and Typical Part 91 Pilots. To learn about new required equipment notes on FAA charts, see New Equipment Required Notes.

KRNO-ILSorLOCZRwy16R

But the equipment required notes for this ILS approach include “RNAV-1 GPS required.”

KRNO-ILSorLOCZRwy16R-notes
A review of the plan view and missed approach track show why GPS is necessary to fly this procedure.

KRNO-ILSorLOCZRwy16R-Plan

First, you need GPS to fly transitions from most of initial fixes, which are RNAV waypoints marked by a star symbol.

RNAV-Waypoint-Symbol

Only LIBGE, directly north of the runway, is a non-RNAV IAF.

For example, HOBOA, KLOCK, BELBE, and WINRZ are all RNAV waypoints that serve as IAFs or IFs. Now, NORCAL Approach might provide vectors to the final approach course, but if you want to fly this procedure you should be prepared for a clearance direct to one of those fixes (see Avoiding the Vectors-to-Final Scramble).

Note also that entire missed approach track requires use of GNSS.

Two of the transitions are of special note. The “arcs” that begin at ZONBI and SLABS are radius-to-fix (RF) legs that are part of the transitions that begin at HOBOA and KLOCK. Each of those fixes is distinguished by the notes “RNP-1 GPS REQD” and “RF REQD.”

The first note means that your GPS must meet the RNP 1 standard, which is used for terminal procedures such as SIDs and STARs, the initial phases of approaches, and missed-approach segments. (For more information about RNP, see RNP Procedures and Typical Part 91 Pilots.)

Until recently, RF legs were included only in Authorization Required (AR) procedures. But as I explained in Garmin GTN Avionics and RF Legs, certain RF legs are now available if you have an appropriate GNSS navigator, updated system software, an electronic HSI, and other equipment. Some limitations on flying such RFs also apply, as described in that earlier post.

Suppose that you choose the less intimidating ILS X or LOC X RWY 16R to the same runway. A review of the notes and the plan view shows that even this conventional-looking ILS also requires RNAV 1 GPS, both to fly the transition from WINRZ and the missed approach track.

KRNO-ILSorLOCXRwy16R.jpg

Update on RNAV (GPS) Approaches

The FAA continues to publish more GPS-based instrument procedures. The latest inventory shows that as of February 6, 2014, there are 13,134 RNAV (GPS) approaches available for general use in the U.S. National Airspace System. (That number doesn’t include the RNP authorization-required procedures available only to pilots and aircraft that meet the requirements of AC 90-101A. More about RNP and AR procedures here.)

By comparison, there are 5,794 ILS, LOC, NDB, and VOR approaches (again, not counting CAT II, CAT III, and other procedures that require special training, equipment, and authorizations).

RNAV (GPS) Procedures  

GPS (Stand – Alone)

140

RNAV (LNAV)

5,832

RNAV (VNAV)

3,254

RNAV (LPV)

3,375

RNAV (LP)

533

Total

13,134

Conventional Approaches  

ILS

1,285

LOC

1,439

LOC (B/C)

72

NDB

780

VOR

1,273

VOR/DME

945

Total

5,794

Here’s a pie chart that shows the relative shares of different types of instrument approach procedures in the U.S.

RNAVApproaches

Perhaps more important to general-aviation pilots is the fact that so many of the RNAV (GPS) procedures—especially those with LPV minimums—are at smaller airports that don’t have an ILS:

  • 3,364 LPVs serving 1,661 airports
  • 2,262 LPVs to non-ILS runways
  • 1,535 LPVs to non-ILS airports
  • 1,102 LPVs to ILS runways
  • 2,020 LPVs to non-Part 139 airports (airports not approved for airline operations)
  • 880 LPVs with DA < 250 HAT
  • 854 LPVs with DA = 200 HAT

Handy WAAS and RNAV (GPS) Approach Fact Sheets

You can find a couple of handy FAA fact sheets on WAAS and RNP Approaches (which most of us know as RNAV (GPS) approaches at the FAA website, here.

The WAAS fact sheet outlines the advantages of a WAAS-capable navigator.

Required Navigation Performance (RNP) Approaches (APCH) succinctly explains the different lines of minimums and provides helpful references to ACs, the AIM, etc.

FAA Proposed Policy for Discontinuance of Certain Instrument Approach Procedures

Here’s the link to the notice in the Federal Register. Excerpts:

As new technology facilitates the introduction of area navigation (RNAV) instrument approach procedures over the past decade, the number of procedures available in the National Airspace System has nearly doubled. The complexity and cost to the Federal Aviation Administration (FAA) of maintaining the existing ground based navigational infrastructure while expanding the new RNAV capability is not sustainable. The FAA is considering the cancellation of certain Non-directional Beacon (NDB) and Very High Frequency (VHF) Omnidirectional Radio Range (VOR) instrument approach procedures (IAP) at airports that have multiple instrument approach procedures. The FAA proposes specific criteria to guide the identification and selection of appropriate NDB and VOR instrument approach procedures that can be considered for cancellation. The VOR IAPs associated with this cancellation initiative would be selected from the criteria outlined below. This Notice is not a part of the FAA’s VOR minimum operating network (MON) initiative

By this notice, the FAA seeks comments on proposed criteria that would facilitate the FAA’s determination of which procedures can be considered for cancellation. After reviewing the comments submitted to this notice, the FAA will use the criteria for selection of potential NDB and VOR procedures for cancellation. Once the criteria are established and the FAA considers IAPs for cancellation, the FAA will publish a list of potential IAPs in the Federal Register for notice and comment. Submitted comments will be reviewed and addressed in the final list of subject IAPs published in the Federal Register. The criteria proposed in this notice does not affect any NAS navigational back-up plans and is not a part of the FAA’s VOR minimum operating network (MON) initiative…

The NDB and VOR IAPs recommended for cancellation would be selected at airports using the following criteria. It must be noted that all airports that have existing RNAV and ground-based IAPs would maintain at least one RNAV and one ground-based IAP.

Airports that would be considered for NDB or VOR IAP cancellation:

— All airports with an NDB IAP.

—All airports with a VOR/DME RNAV IAP, unless it is the only IAP at the airport.

—All airports with two or more ground-based IAPs and an RNAV IAP.

—All airports with multiple, redundant ground-based IAPs (e.g., three VOR procedures).

Additional consideration would be given to the following factors in determining the list of potential candidates for cancellation:

—Prevailing wind runways.

—Prevailing runway alignment during adverse weather operations.

—If an airport has a published ILS IAP and additional ground-based IAPs, cancel the procedure to the same runway as the ILS.

—For airports with multiple VOR and NDB IAP’s, retain the IAP with the lowest minimums (if minimums are within 20 feet of each other retain the procedure that allows optimum use by all customers (i.e. VOR and VOR/DME retain VOR because there are no equipage limitations).

Airports that would not be considered for NDB or VOR IAP cancellations:

—Airport with only RNAV/RNPs IAPs published.

—Airport with only one ground-based procedure.

—Airports will not be considered if cancellation would result in removing all IAPs from the airport.

Lastly, the FAA is not considering the following types of procedures for cancellation:

PBN Procedures (RNAV or RNP).

ILS procedures.

Localizer procedures.

TACAN procedures.

Standard Instrument Arrivals (STARs).Show citation box

Standard Instrument Departures (SIDs).

New ATC Phraseology for RNAV Aircraft

The FAA has updated its Air Traffic Control handbook (JO 7110.65) with changes to approach clearances issued by controllers. The new procedures and phraseology, which primarily affect RNAV-equipped aircraft, were published in this notice (PDF), are effective June 3, 2013.

Here’s a summary of the key changes:

  • This change provides guidance when a controller does not require an aircraft to fly the hold-in-lieu-of procedure turn but requires the aircraft to fly the straight-in approach.
  • Vectoring to a fix along the final approach course prior to the final approach fix (FAF) is permitted. Appropriately -equipped area navigation (RNAV) aircraft may be cleared to the intermediate fix (IF) on conventional and RNAV instrument approach procedures when the IF is identified with an “IF” on the instrument approach procedure. Procedures and graphics are provided for an aircraft on unpublished routes cleared direct to a fix between the IF and FAF.
  • Guidance is provided for when an aircraft will fly a radius to fix (RF) leg, published on an RNAV approach.

The first item should eliminate confusion among many pilots when a approach chart shows a holding pattern in lieu of a procedure turn. Controllers will now explicitly clear aircraft “straight-in” when they don’t want the pilot to fly the holding pattern.

The second item will reduce radio chatter and make it easier for RNAV-equipped aircraft to fly efficient approaches. Pilots may want to review how they load approaches into GPS navigators to avoid what I call the vectors-to-final scramble. The last item in the summary refers to RF legs, which at present are part of authorization-required RNP approaches that aren’t available to typical GA pilots.

LP Approaches are now Available

The 7 February 2013 NavData update from Jeppesen includes RNAV approaches with LP (localizer performance) minimums. You can read more about LP at my blog here and in AIM 1-1-20 (b)(3):

A new nonprecision WAAS approach, called Localizer Performance (LP) is being added in locations where the terrain or obstructions do not allow publication of vertically guided LPV procedures. This new approach takes advantage of the angular lateral guidance and smaller position errors provided by WAAS to provide a lateral only procedure similar to an ILS Localizer. LP procedures may provide lower minima than a LNAV procedure due to the narrower obstacle clearance surface.

NOTE–WAAS receivers certified prior to TSO C-145b and TSO C-146b, even if they have LPV capability, do not contain LP capability unless the receiver has been upgraded. Receivers capable of flying LP procedures must contain a statement in the Flight Manual Supplement or Approved Supplemental Flight Manual stating that the receiver has LP capability, as well as the capability for the other WAAS and GPS approach procedure types.

As noted above, you must have a WAAS-capable, IFR-approved GPS navigator to fly LP procedures. In addition, your unit must have the correct operating system software installed, and the supplement to your AFM must permit you to fly to LP minimums based on the equipment installed in your aircraft.

At present, there are 413 Localizer Performance (LP) approach procedures in the U.S. The map below is a bit out of date, but it gives you a general idea of where these procedures are located. You can find lists of approaches with LP minimums at this FAA website. The information is in Microsoft Excel worksheets that you can filter and sort.