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:

New Edition of the Instrument Procedures Handbook

The FAA has published a new edition of the Instrument Procedures Handbook (FAA-H-8083-16). You can download the free PDF from the FAA website, here.


This is first major update to the IPH since 2007. As the preface notes:

It is designed as a technical reference for all pilots who operate under instrument flight rules (IFR) in the National Airspace System (NAS). It expands and updates information contained in the FAA-H-8083-15B, Instrument Flying Handbook, and introduces advanced information for IFR operations. Instrument flight instructors, instrument pilots, and instrument students will also find this handbook a valuable resource since it is used as a reference for the Airline Transport Pilot and Instrument Knowledge Tests and for the Practical Test Standards. It also provides detailed coverage of instrument charts and procedures including IFR takeoff, departure, en route, arrival, approach, and landing. Safety information covering relevant subjects such as runway incursion, land and hold short operations, controlled flight into terrain, and human factors issues also are included.

Updates to AIM, Effective April 3, 2014

The FAA has published updates to the Aeronautical Information Manual, effective April 3, 2014. You can download the PDF version of the new AIM here. The Explanation of Changes section describes the updates to the AIM. The online version of the new edition will be available on the FAA website on the effective date, here.

Key changes for general aviation pilots include:

1−1−3. VHF Omni−directional Range (VOR)

The only positive method of identifying a VOR is by its Morse Code identification or by the recorded
automatic voice identification which is always indicated by use of the word “VOR” following the
range’s name…Some VOR receivers are capable of identifying the VOR and will display the identifier of the VOR if it has successfully done so. However, it is still the pilot’s responsibility to verify the identity of the VOR by conventional methods.

1−1−18. Global Positioning System (GPS)—j. 2. Computer Navigation Fix (CNF)

A Computer Navigation Fix (CNF) is also a point defined by a latitude/longitude coordinate and is required to support area navigation (RNAV) system operations. The GPS receiver uses CNFs in conjunction with waypoints to navigate from point to point. However, CNFs are not recognized by Air Traffic Control (ATC). ATC does not maintain CNFs in their database and they do not use CNFs for any air traffic control purpose. CNFs may or may not be charted on FAA aeronautical navigation products, are listed in the chart legends, and are for advisory purposes only. Pilots are not to use CNFs for point to point navigation (proceed direct), filing a flight plan, or in aircraft/ATC communications. CNFs that do appear on aeronautical charts allow pilots increased situational awareness by identifying points in the aircraft database route of flight with points on the aeronautical chart. CNFs are random five−letter identifiers, not pronounceable like waypoints, and placed in parenthesis. Eventually, all CNFs will begin with the letters “CF” followed by three consonants (for example, CFWBG). This five−letter identifier will be found next to an “x” on enroute charts and possibly on an approach chart. On instrument approach procedures(charts) in the terminal procedures publication, CNFs may represent unnamed DME fixes, beginning and ending points of DME arcs, and sensor (ground−based signal i.e., VOR, NDB ILS) final approach fixes on GPS overlay approaches. These CNFs provide the GPS with points on the procedure that allow the overlay approach to mirror the ground−based sensor approach. These points should only be used by the GPS system for navigation and should not be used by pilots for any other purpose on the approach. The CNF concept has not been adopted or recognized by the International Civil Aviation Organization (ICAO).

Here are examples of CNFs as shown on the plan view of the ILS Y RWY 27 at KYKM:


5−4−1. j. Waypoints

1. GPS receivers navigate from one defined point to another retrieved from the aircraft’s on board navigational database. These points are waypoints (5-letter pronounceable name), existing VHF intersections, DME fixes with 5-letter pronounceable names and 3-letter NAVAID IDs. Each waypoint is a geographical location defined by a latitude/longitude geographic coordinate. These 5-letter waypoints, VHF intersections, 5-letter pronounceable DME fixes, and 3-letter NAVAID IDs are published on various FAA aeronautical navigation products (IFR Enroute Charts, VFR Charts, Terminal Procedures Publications, etc.)…

3. GPS approaches use fly−over and fly−by waypoints to join route segments on an approach. Fly−by waypoints connect the two segments by allowing the aircraft to turn prior to the current waypoint in order to roll out on course to the next waypoint. This is known as turn anticipation and is compensated for in the airspace and terrain clearances. The MAWP and the missed approach
holding waypoint (MAHWP) are normally the only two waypoints on the approach that are not fly−by waypoints. Fly−over waypoints are used when the aircraft must overfly the waypoint prior to starting a turn to the new course. The symbol for a fly-over waypoint is a circled waypoint. Some waypoints may have dual use; for example, as a fly-by waypoint when used as an IF for a NoPT route and as a fly-over waypoint when the same waypoint is also used as an IAF/IF hold-in-lieu of PT. When this occurs, the less restrictive (fly-by) symbology will be charted. Overlay approach charts and some early stand-alone GPS approach charts may not reflect this convention.

4. Unnamed waypoints for each airport will be uniquely identified in the database. Although the identifier may be used at different airports (for example, RW36 will be the identifier at each airport with a runway 36), the actual point, at each airport, is defined by a specific latitude/longitude coordinate.

5. The runway threshold waypoint, normally the MAWP, may have a five−letter identifier (for example, SNEEZ) or be coded as RW## (for example, RW36, RW36L). MAWPs located at the runway threshold are being changed to the RW## identifier, while MAWPs not located at the threshold will have a five− letter identifier. This may cause the approach chart to differ from the aircraft database until all changes are complete. The runway threshold waypoint is also used as the center of the Minimum Safe Altitude (MSA) on most GPS approaches.

5−4−1. l. Impact of Magnetic Variation on RNAV Systems

1. Differences may exist between charted magnetic courses on ground-based navigational aid
(NAVAID) instrument flight procedures (IFP), area navigation (RNAV) procedures, and RNAV systems on enroute charts, approach charts, and Standard Instrument Departure/Standard Terminal Arrival (SID/STAR) charts. These differences are due to the magnetic variance used to calculate the magnetic course. Every leg of an instrument procedure is first computed along a desired ground track with reference to true north. A magnetic variation correction is then applied to the true course in order to calculate a magnetic course for publication. The type of procedure will determine what magnetic variation value is added to the true course. A ground-based NAVAID IFP applies the facility magnetic variation of record to the true course to get the charted magnetic course. Magnetic courses on RNAV procedures are calculated two different ways. SID/STAR procedures use the airport magnetic variation of record, while IFR enroute charts use magnetic reference bearing. RNAV systems make a correction to true north by adding a magnetic variation calculated with an algorithm based on aircraft position, or by adding the magnetic variation coded in their navigational database. This may result in the RNAV system and the procedure designer using a different magnetic variation, which causes the magnetic course displayed by the RNAV system and the magnetic course charted on the IFP plate to be different. It is important to understand, however, that RNAV systems (with the exception of VOR/DME RNAV equipment) navigate by reference to true north and display magnetic course only for pilot reference. As such, a properly functioning RNAV system, containing a current and accurate navigational database, should still fly the correct ground track for any loaded instrument procedure, despite any differences in magnetic course that may be attributed to magnetic variation application. Should significant differences between the approach chart and the RNAV system avionics’ application of the navigation database arise, the published approach chart, supplemented by NOTAMs, holds precedence.

2. The course into a waypoint may not always be 180 degrees different from the course leaving the previous waypoint, due to the RNAV system avionics’ computation of geodesic paths, distance between waypoints and differences in magnetic variation application. Variations in distances may also occur since RNAV system distance−to−waypoint values are along−track distances (ATD) computed to the next waypoint and the DME values published on underlying procedures are slant−range distances measured to the station. This difference increases with aircraft altitude and proximity to the NAVAID.

5−3−4. Airways and Route Systems

(b) Unpublished RNAV routes are direct routes, based on area navigation capability, between waypoints defined in terms of latitude/longitude coordinates, degree−distance fixes, or offsets from established routes/airways at a specified distance and direction. Radar monitoring by ATC is required on all unpublished RNAV routes, except for GNSS−equipped aircraft cleared via filed published waypoints recallable from the aircraft’s navigation database.

5−4−1. Standard Terminal Arrival(STAR), Area Navigation (RNAV) STAR, and Flight Management System Procedures (FMSP) for Arrivals

This change incorporates updated guidance on resumption of published altitude and speed restrictions, guidance on what is expected of aircrews when issued a “climb via” clearance, and clarifies the expectation that pilots will advise the receiving controller of the altitude being vacated and the altitude they are climbing to when changing frequencies.

For all the details, see this section in the update to the AIM.

i. 5−4−5. Instrument Approach Procedure Charts

This change updates guidance to reflect the fact that the initial approach fix (IAF) waypoint is not an IAF, but an intermediate fix (IF). This change also updates guidance on descent below the minimum descent altitude (MDA).

For all the details, see this section in the update to the AIM.

7−1−11. Flight Information Services (FIS)

This change updates information and guidance to modify outdated information, reflect policy and terminology changes, and address changing technologies.

For all the details, see this section in the update to the AIM.

7−1−14. ATC Inflight Weather Avoidance Assistance

This change was added to expand the meaning of the phrase “when able” when used in conjunction with a clearance to deviate around weather. The clearance to deviate is clarified to allow maneuvering within the lateral limits of the deviation clearance.

For all the details, see this section in the update to the AIM.

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)












Conventional Approaches  















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


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 RNAV (GPS) approaches at the FAA website, here.

WAAS: Quick Facts outlines the advantages of a WAAS-capable navigator.

RNAV (GPS) Approaches succinctly explains the different lines of minimums and provides helpful references to ACs, the AIM, etc.

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IACO Flight Plan Equipment Codes for Aircraft with IFR GPS

In November 2012, FAA adopted new requirements and procedures for using ICAO-format flight plans. Pilots planning IFR flights within the borders of the U.S. are now required to file ICAO-format flight plans if:

  • The flight will enter international airspace (including Oceanic airspace controlled by FAA facilities). Even if your flight just crosses a border, such as flying through Canadian airspace on a trip that departs from and lands at a U.S. airport, you must file an ICAO flight plan.
  • You expect routing or separation based on Performance Based Navigation, for example, RNAV-based routes, departures, and arrivals. (More about PBN and RNAV levels in PBN and RNP Confusion, below.)
  • The flight will enter RVSM (Reduced Vertical Separation Minimum) airspace (i.e., above FL290).
  • You expect services based on ADS-B.

A detailed explanation of the ICAO flight plan form is available here.

In November 2013, FAA updated and simplified some of the requirements for filing ICAO flight plans for domestic use. You can read about those changes here (PDF). For most GA pilots operating under 14 CFR Part 91, the key changes are (1) The FAA requires PBN capability be filed in order to receive the desired PBN routing, e.g. RNAV routes; (2) Recent changes make the inclusion of the PBN/ field required and the NAV/ field optional when an R is filed in ICAO Item 10. (PBN/ has been required but it was not enforced by the automation until recently).

Other Reasons to File ICAO Flight Plans

Even if you aren’t required to file an ICAO flight plan, you may want to start using that format for IFR flight plans if you fly an airplane equipped with an IFR-approved GPS, especially if the box is WAAS-approved, or your aircraft is equipped with ADS-B in/out equipment, such as the Garmin GDL 88.

You can file an ICAO flight plan online through Lockheed-Martin Flight Services (the official FSS) and several free third-party services, including DUAT, DUATS, and FltPlan.com.

Confusing Codes

Many pilots are confused by elements of the ICAO flight plan format, especially the multiple aircraft equipment codes that you must include to inform ATC of the gizmos and capability that are installed in your aircraft.

The following guide should help you sort out those ICAO codes if you fly a typical light GA aircraft equipped with at least one WAAS-capable, GPS navigator that is approved to fly RNAV (GPS) approaches. Examples of such avionics include:


Here’s a look at the relevant parts of the ICAO flight plan form as shown on the Lockheed-Martin FSS website. I’ve filled in the information for my Beechcraft A36 Bonanza (ICAO identifier BE36), which is equipped with a GTN750, a Garmin GTX 327 transponder (not Mode S), and the GDL 88 ADS-B transmitter and receiver. This aircraft also has a Bendix/King DME receiver. The example is for an IFR trip from KBFI to KGEG in the Pacific Northwest. The route includes the ZOOMR1 STAR into KGEG.


Basic Information

The first few items are the same for all typical IFR general aviation flights:

  • Flight Rule: IFR
  • Flight Type: G (for general aviation)
  • Number of Aircraft: 1 (i.e., not a formation flight)
  • Wake Turbulence Category: L (for light)
  • Aircraft Type: The official ICAO designator for the make and model of aircraft you fly (e.g., BE36, C172, C210, M20P, PA28A, etc.)

Aircraft Equipment

On the familiar FAA domestic flight plan form, equipment suffixes for typical GA pilots are simple, and if you’re flying a GPS-equipped airplane with a Mode C transponder, the basic /G is all you need.

But the ICAO form captures many more details about the equipment installed in your aircraft, and the fun typically begins with this item.

For a WAAS-equipped aircraft such as we’re discussing, you should enter the following codes in the Aircraft Equipment box:



As you can see in the illustration from the Lockheed-Martin FSS web form, these letters represent the following equipment:

  • S: Standard communication and navigation receivers/transmitters (VOR, VHF communications radios, and ILS receiver). If you enter S in this box, you shouldn’t include the letters L (ILS), O (VOR), or V (VHF) here. S includes that equipment.
  • B: LPV approach capability. If you have a WAAS GPS, but your installation isn’t approved for LPV procedures (see the user’s guide and AFM supplement), omit this letter.
  • D: DME
  • G: IFR-approved GPS (the preferred term is now GNSS, Global Navigation Satellite System)
  • R: PBN approved. This letter means that your aircraft meets basic RNP standards. You must include this letter, and associated information in the Other Information box, to ensure that the computer will accept a routing that includes RNAV routes, SIDs, STARs, or charted ODPs. See PBN and RNP Confusion, below.
  • Z: Indicates additional information to be added to the Other Information box, below.
  • If you still have an ADF, include F.
  • If you don’t have DME, omit the D.

PBN and RNP Confusion

The aviation world uses RNP (required navigation performance) for two related, but different purposes.

In general, RNP is an RNAV specification (e.g., RNAV 5, RNAV 2, and RNAV 1) that indicates that an aircraft is capable of maintaining a course (track) within designated limits 95 percent of the time. For example, RNAV 5 means the aircraft as equipped can reliably maintain a track with 5 nm; RNAV 2 limits are 2 nm, and so forth. If your aircraft is equipped with an IFR-approved GPS authorized to fly RNAV (GPS) approaches, it matches this sense of RNP and PBN.

The basic RNP (RNAV) specifications used in the U.S. (RNP 0.3, RNP 1.0, RNP 2.0, and RNP 1.0) are shown in the following illustration from the Instrument Flying Handbook (FAA H-8083-15B). For more information about RNP and RNAV specifications, see “Required Navigation Performance” on page 9-44 of the IFH.


Current WAAS-approved GPS receivers for typical GA aircraft, such as those listed earlier, meet the U.S. RNP specifications, as described in AC 90-100A: U.S Terminal and En Route Area Navigation (RNAV) Operations and its associated AC90-100 Compliance Table (a Microsoft Excel worksheet). To confirm your GPS receiver’s capabilities, check the user guides and the AFM supplements for the equipment installed in your aircraft.

The term RNP is also applied as a descriptor for airspace, routes, and procedures (including departures, arrivals, and IAPs). RNP can apply to a unique approach procedure or to a large region of airspace. In this sense, RNP means something similar to Category II and Category III instrument approaches. For example, an approach with RNP in the title (e.g., RNAV (RNP) Z RWY 16R) requires special equipment and detailed crew training/qualification. Such RNAV (RNP) approaches include the note AUTHORIZATION REQUIRED on the chart.

For more information about RNP approaches, see RNP Procedures and Typical Part 91 Pilots and Garmin Radius to Fix Leg Project Report here at my blog.

Surveillance Equipment (Transponder and ADS-B)

This box on the ICAO form tells ATC what type of transponder and related equipment are installed in your aircraft.


  • For most GA pilots flying IFR, this box will include at least C, for a transponder with altitude-reporting capability.
  • If you have a Mode S transponder, you should select the appropriate letter, E, H, I, L, P, S, or X, based on the information in the user guide and AFM supplement for your transponder.
  • If you have ADS-B equipment installed (not a portable ADS-B receiver such as the Stratus or Dual XGPS170), include U1 or U2. The Garmin GDL 88 in my airplane both transmits and receives ADS-B signals, so I add U2 to this box.

Other Information

The final box for designating your RNAV capabilities is Other Information. You must use prefixes, followed by letters, to include different categories of information.

As described above here and here, it’s important to add a /PBN group in this box to ensure that the ATC system understands the RNP/RNAV capabilities of your aircraft.


If you have a GPS approved for at least IFR en route and terminal operations, add the following letters:

  • B2, which designates RNAV 5 capability based on GPS (GNSS)
  • C2, which designates RNAV 2 capability based on GPS (GNSS)
  • D2, which designates RNAV 1 capability based on GPS (GNSS)

You should also add a /NAV group in this box to indicate your RNAV capability. The letters D1E2A1 after /Nav indicate that you have RNAV 1 capability for departure, RNAV 2 capability for the en route segment, and RNAV 1 capability for arrival.



These groups and letters mean that you can fly RNAV routes (e.g., T-routes), RNAV SIDs and STARs, and charted ODPs (charted ODPs are often RNAV procedures, usually based on GPS).

For more information about charted ODPs, see:

Don’t worry about the options in the RNP Specifications part of this box. Unless you are authorized to fly RNAV (RNP) procedures (see above), these items don’t apply to you.


Here’s a quick review of what to put in the equipment-related boxes of the ICAO flight plan form if, like me, you fly an aircraft with one of the common IFR-approved, WAAS-capable GPS receivers:

  • Aircraft Equipment: SBDGR.
  • Surveillance Equipment: C (for a Mode C transponder).
    (If you have ADS-B in/out capability, such as a Garmin GDL 88, add U2. If you have a Mode S transponder, include the appropriate letter for your model.)
  • Other Information: PBN/B2C2D2 NAV/RNVD1E2A1



October Updates to the AIM for IFR Pilots with GPS

FAA has released updates to the AIM, effective October 24, 2013, that may be of interest to IFR pilots who fly with an IFR-approved GPS. The key changes involve:

  • Equipment codes used on domestic flight plans
  • Requirements for radar monitoring on direct routes, especially for aircraft equipped with an IFR-approved GPS.

The changes include new terms—or clarifications of existing terms: impromptu RNAV routes and point-to-point routes.

You can read the revised AIM pages 5-1-13, 5-1-15, and 5-3-6 here (PDF). They will be included in the next scheduled update to the AIM.

Guidance concerning these changes for air traffic controllers is published in an update, “Global Navigation Satellite System (GNSS) Equipped Aircraft Operating on Random Routes,” to the ATC handbook, JO 7110.639. It’s available here (PDF).

Domestic Flight Plan Equipment Codes

The first change concerns equipment codes for domestic flight plans. Fortunately, for typical GA pilots flying with an IFR-approved GPS, the familiar /G suffix remains in effect. You should use the new /V or /S codes only if you have no transponder or a transponder without Mode C.

If you operate in the RVSM airspace and/or use other equipment (such as an INS or a DME/DME FMS) to meet RNAV requirements, FAA has published new equipment suffixes, which are described in the revised pages.

Note that these new equipment codes apply only when using the domestic FAA flight plan format. If you use the ICAO flight plan form, use the equipment codes designated for that format.

Off-Airway Routes with IFR-Approved GPS

The AIM update changes some considerations for filing and flying off-airway and direct routes if your aircraft is equipped with an IFR-approved GPS.

First, the new AIM 5-1-15 (d) Area Navigation (RNAV) formally introduces the term impromptu RNAV routes. In the update for air traffic controllers, a random impromptu route is defined as:

…[A] direct course initiated by ATC or requested by the pilot during flight. Aircraft are cleared from their present position to a NAVAID, waypoint, fix, or airport.

An impromptu RNAV route can be approved only in a radar environment, and ATC will monitor the flights on such routes, but navigation remains the responsibility of the pilot.

The updated AIM 5-3-4 (3) Area Navigation (RNAV) Routes describes unpublished RNAV routes (that is, routes other than T-routes and Q-routes):

Unpublished RNAV routes are direct routes, based on area navigation capability, between waypoints defined in terms of latitude/longitude coordinates, degree−distance fixes, or offsets from established routes/airways at a specified distance and direction.

Radar monitoring is still generally required for such unpublished RNAV routes.

But if you have an IFR-approved GPS, and you are cleared to fly a direct route based on published waypoints recalled from the GPS database, radar monitoring is no longer required. Such routes are also called point-to-point routes.

The maximum distance between the published waypoints is 500 nm, and the assigned altitude must be at or above the highest minimum instrument altitude (MIA) along the route, which provides obstacle clearance 4 miles either side of the route centerline.

For example, a point-to-point route from an airport in the Seattle area to Newport, OR (KONP) might use named RNAV fixes en route and end at a VOR: HAROB FEBOT ERAVE REDHK ONP. If you’re flying a GPS-equipped aircraft, radar monitoring wouldn’t be required along that route.



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