Stand-Alone DMEs on Charts

As the FAA moves ahead it with its plans to decommission about one-third of the existing network of VORs in the continental U.S. (for more information, see Another Update on VOR Decommissioning and its related posts), a new type of navaid–a stand-alone DME facility–is appearing on aeronautical charts.

Here’s an example southwest of Las Vegas, NV. Note the identification and frequency box for the GOODSPRINGS DME (GOG). The site of the transmitter is shown by the small blue box indicated by the red arrow.

GoodspringsDME.jpg

Here’s the same facility on a low-altitude IFR chart:

GoodspringsDME-IFR.jpg

You can read more about these stand-alone DME facilities in DME Facilities – Charting and MAGVAR Issues (PDF), which describes the discussions of the Aeronautical Charting Forum, an FAA-industry group.

These stand-alone DMEs are primarily for use by aircraft with DME-DME area navigation equipment, and in many cases, they are left over when the VORs they were associated with are shut down. Where necessary, new DMEs will be added to support RNAV procedures based on DME-DME as an alternative to GPS. As you can see from the chart, these DMEs do not provide azimuth (course) information like a VOR-DME or VORTAC. They are simply DMEs.

If, like most IFR pilots flying typical GA aircraft, you use GPS as your primary navigation source, these charted stand-alone DMEs are of most interest as fixes that you can include in a route or flight plan. If you still have a DME receiver in your airplane, you can tune, identify, and reference these DMEs as you fly.

ATC Telephone Numbers for IFR Clearances

The FAA has announced that it will publish telephone numbers for some ATC facilities that provide IFR clearances and cancellations of IFR flight plans via the phone in the Chart Supplement (formerly known as the A/FD). FAA planned to begin implementation of the change on October 1, 2016 and complete the process by June 30, 2017.

The basic information was provided in a recommendation document (ACF-CG RD 16-020309) at the Aeronautical Charting Forum, which reads in part:

Subject: Publication of approach control phone numbers for purposes of Clearance
Delivery and/or IFR flight plan cancellation.

Background/Discussion: In accordance with the Administrator’s NAS Efficient Streamlined Services Initiative Air Traffic, Flight Service, and NATCA have agreed that air traffic facilities currently providing clearances to pilots via telephone (informally) will have their numbers published in the appropriate Chart Supplement, US. These same facilities will have the option to have a separate phone line installed for IFR flight plan cancellations, which will also be published. The attached Policy Decision Memorandum identifies the affected 32 Air Traffic facilities and reflects approval by VP System Operations, VP Air Traffic Services, and VP Technical Operations. Also attached are the Scoping Document Workgroup Agreement, Safety Risk Management Document, and Implementation Plan.

Recommendations: Publish the approach control phone numbers for Clearance Delivery and/or IFR flight plan cancellation in the Chart Supplement US, for example:

For CLNC DEL CTC BOSTON APCH (603) 594-5551

And, when available, for those facilities with the IFR cancellation line

To CANCEL IFR CTC BOSTON APCH (603) 594-5552

The official FAA memoranda that describe the details are attached to the recommendation documented linked above.

The list of TRACONs and towers (subject to revision) that will issue clearances directly to pilots via telephone includes:

  1. A90 -Boston
  2. C90 – Chicago
  3. Dl O -Dallas-Fort Worth
  4. D21 – Detroit
  5. F 11 – Central Florida
  6. 190 – Houston
  7. L30 – Las Vegas
  8. M03 – Memphis
  9. N90 -New York
  10. NCT -Northem California
  11. P80 – Portland
  12. R90 – Omaha
  13. S46 – Seattle
  14. S56 – Salt Lake
  15. T75 – Louis
  16. U90 -Tucson
  17. Y90 – Yankee
  18. ABE – Allentown, PA
  19. AUS -Austin, TX
  20. AVP – Scranton, PA
  21. ENA -Nashville, TN
  22. CLT – Charlotte,NC
  23. CRP – Corpus Christie, TX
  24. DAB -Daytona, FL
  25. IND – Indianapolis, IN
  26. MCI -Kansas City, MO
  27. MDT -Harrisburg, PA
  28. MSY -New Orleans, LA
  29. ORF -Norfolk, VA
  30. PHL – Philadelphia, PA
  31. SAT – San Antonia, TX
  32. PCT – Potomac, VA

Latest Info on VOR Shutdowns

The FAA recently provided an update on its plans to decommission about 30 percent (308) of the existing network of 957 VORs by 2025. The presentation, made at the April 2016 meeting of the Aeronautical Charting Forum, is available here (PDF).

Some highlights:

As I’ve noted in previous posts on this topic (e.g., here), the basic plan remains as follows:

  • Decommission about 308 VORs in two phases. Phase 1 runs from FY2016-FY2020. Phase 2 runs from FY2021-FY2025.
  • About 649 VORs will remain in service. In fact, many of those VORs will be upgraded to expand their service volumes.
  • Most of the VORs to be shut down will be in the Central (162) and Eastern (131) U.S. Only about 15 VORs will be decommissioned in the West.

The list of the first VORs to be shut down is available from AOPA here (PDF). AOPA also has good background about the program to decommission VORs on its website.

To provide backups should GPS signals fail or be disrupted, the FAA will retain a minimum operational network (MON) of VORs and MON airports that have ILS and/or VOR approaches.

Those MON airports and VORs are designed to enable pilots to:

  • Revert from PBN [i.e., GPS-based] to conventional navigation in the event of a Global Positioning System (GPS) outage;
  • Tune and identify a VOR at a minimum altitude of 5,000 feet above ground level or higher;
  • 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 where the capability currently exists; 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.

You can learn more about MON airports in this presentation (PDF) from the ACF meeting.

Use of IFR GPS on Conventional Approaches

FAA has published an update to the AIM, effective 26 May 2016, and it includes a big change if you have an IFR-approved GPS [i.e., a “suitable navigation system” as defined in AC 20-138 and AIM 1-2-3 (b).]

Now, if you fly a conventional approach based on a VOR or NDB (but not a localizer), you can fly the procedure entirely with the GPS, provided you can monitor (using a separate CDI or a bearing pointer) the VOR or NDB facility specified for the approach.

The new language is in section 1−2−3. Use of Suitable Area Navigation (RNAV) Systems on Conventional Procedures and Routes.

The summary of changes to this AIM update notes that:

This change allows for the use of a suitable RNAV system as a means to navigate on the final approach segment of an instrument approach procedure (IAP) based on a VOR, TACAN, or NDB signal. The underlying NAVAID must be operational and monitored for the final segment course alignment.

The new text in the AIM is in paragraph 5 of AIM 1-2-3:

5. Use of a suitable RNAV system as a means to navigate on the final approach segment of an instrument approach procedure based on a VOR, TACAN or NDB signal, is allowable. The underlying NAVAID must be operational and the NAVAID monitored for final segment course alignment.

This change is the result of a discussion at the Aeronautical Charting Forum in 2014.

Changes in AIM Effective 26 May 2016

FAA has published an update to the AIM, effective 26 May 2016, and it includes several important changes of interest to typical general-aviation pilots:

1−2−3. Use of Suitable Area Navigation (RNAV) Systems on Conventional Procedures
and Routes

This change allows for the use of a suitable RNAV system as a means to navigate on the final approach segment of an instrument approach procedure (IAP) based on a VOR, TACAN, or NDB signal. The underlying NAVAID must be operational and monitored for the final segment course alignment. [For more information about this item, see the detailed discussion here.]

3−2−3. Class B Airspace
This change adds an RNAV Receiver as an option for instrument flight rule (IFR) navigation requirement IAW 91.131 (c)(1).

3−2−6. Class E Airspace

This change updates the definition, vertical limits, and types of Class E airspace. The change more accurately reflects Class E airspace regulatory information in 14 CFR Part 71 and more clearly states that Class E arrival extensions have the same effective times as the airport surface area airspace….

4−3−22. Option Approach
This changes adds verbiage advising pilots to inform air traffic control (ATC) as soon as possible of any delay clearing the runway during their stop−and−go or full stop landing.

5−2−8. Instrument Departure Procedures (DP) − Obstacle Departure Procedures (ODP) and Standard Instrument Departures (SID)
This change adds language advising pilots what to expect when vectored or cleared to deviate off of an SID.

5−4−1. Standard Terminal Arrival (STAR) Procedures
This change adds language advising pilots what to expect when vectored or cleared to deviate off of a STAR. Pilots should consider the STAR cancelled. If the clearance included crossing restrictions, controllers will issue an altitude to maintain. It also adds language advising pilots when to be prepared to resume the procedure. Since all clearances on STARS will not include Descend Via clearances, the word “will” was replaced with “may.”

5−4−7. Instrument Approach Procedures
This change adds a note to provide guidance to pilots regarding what to expect when clearances are issued by ATC to altitudes below those published on IAPs.

Garmin GTN Avionics and RF Legs

The release of updated operating software for Garmin GTN-series avionics brings new capabilities to many typical general aviation pilots who fly under IFR. One of the new features is the ability to fly curved radius-to-fix (RF) legs on some instrument approaches.

image.png

Until recently, RF legs were published only on so-called RNP procedures with authorization required (AR) restrictions (for more information, see AIM 5−4−18: RNP AR Instrument Approach Procedures). But FAA has started publishing some approaches with RF legs (like the example above) that are not designated as RNP AR procedures. And, with some limitations, pilots who fly aircraft equipped with GTN-series avionics should be able to fly the RF legs used as transitions/feeder routes on those approaches. (Note that so far, these approaches don’t require RF capability–conventional transitions/feeder routes and/or radar vectors are also available.)

For more information about RF legs, see RNP Procedures and Typical Part 91 Pilots and Garmin Radius to Fix Leg Project Report here at BruceAir. For additional background on GPS navigation and RNP procedures, see also Updated AC 90-105A.

The revised STC for the GTN series (document 190-01007-A5) notes that:

GPS/SBAS TSO-C146c Class 3 Operation
…The Garmin GNSS navigation system complies with the equipment requirements of AC 90-105 and meets the equipment performance and functional requirements to conduct RNP terminal departure and arrival procedures and RNP approach procedures including procedures with RF legs subject to the limitations herein [emphasis added].

Sections 2.12 RF Legs and 2.13.1 RNP 1.0 RF Leg Types of the STC add the following information:

2.12 RF Legs
This STC does not grant operational approval for RF leg navigation for those operators requiring operational approval. Additional FAA approval may be required for those aircraft intending to use the GTN as a means to provide RNP 1 navigation in accordance with FAA Advisory Circular AC 90-105. [Note that per AC 90-105A, domestic Part 91 operations do not require additional approval–only Part 91 subpart K operations and commercial operations need LOAs or the equivalent FAA approval.]

The following limitations apply to procedures with RF legs:

  • Aircraft is limited to 180 KIAS while on the RF leg
  • RF legs are limited to RNP 1 procedures. RNP AR and RNP <1 are not approved
  • Primary navigation guidance on RF legs must be shown on an EHSI indicator with auto-slew capability turned ON
  • GTN Moving Map, EHSI Map, or Distance to Next Waypoint information must be displayed to the pilot during the RF leg when flying without the aid of the autopilot or flight director.
  • The active waypoint must be displayed in the pilot’s primary field of view…

2.13.1 RNP 1.0 RF Leg Types
AC 90-105 states that procedures with RF legs must be flown using either a flight director or coupled to the autopilot.

This STC has demonstrated acceptable crew workload and Flight Technical Error for hand flown procedures with RF legs when the GTN installation complies with limitation set forth in Section 2.12 of this document. It is recommended to couple the autopilot for RF procedures, if available, but it is not required to do so. See section 4.5 of this manual to determine if this capability is supported in this installation.

At present, only a few non-AR approaches with RF legs meet the criteria in the STC and AC 90-105A. But RF legs could become more common on “standard” procedures to provide paths that offer better noise abatement, reduce airspace conflicts, and improve ATC efficiency, and pilots flying with GTN avionics (or similar navigators offered by other manufacturers) will be able to fly those procedures.

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).