Garmin Updates GTN Trainer App

Garmin has updated the free GTN Trainer app for the iPad. The new version reflects system software 6.62, which includes features added since version 6.5, such as vertical navigation, along track offsets and more.

You can find a detailed discussion of some of these functions at New Garmin GTN 750 Features.


Clearances to GNSS Equipped Aircraft Below the MEA

FAA recently updated Air Traffic Control (JO 7110.65W) to allow IFR clearances to GNSS (i.e., GPS) equipped aircraft on airways below the published minimum en route altitude.

N JO 7110.741, published on September 25, 2017 (now incorporated in Air Traffic Control paragraph 4-5-6), explained that:

This notice…allow[s] IFR certified Global Navigation Satellite System (GNSS) equipped aircraft to be cleared below published Minimum En Route Altitudes (MEA)…

The notice explained that:

MEAs are based in part on ground-based navigational aid reception. The advent of satellite technology provides the opportunity for lower minimum altitudes along certain airways, allowing more altitudes to be usable for more aircraft. This change will facilitate IFR certified GNSS equipped aircraft to fly below published MEAs, but no lower than Minimum Obstruction Clearance Altitudes, Minimum IFR Altitudes, or Minimum Vectoring Altitudes, regardless of radar coverage. This would apply to all applicable airways, rather than being limited to those published with GNSS MEA minimums.

Note that the rule (in 14 CFR §91.177 Minimum altitudes for IFR operations) about flying at the MOCA when you are using VORs still applies:

For aircraft using VOR, VORTAC or TACAN for navigation, this [i.e., flying at the MOCA] applies only within 22 miles of that NAVAID.

The low-altitude en route chart below points out examples of MEAs and MOCAs. (Click here to see the chart at


For example, along a segment of V187 between MOG and MSO, the MEA is 13000. The MOCA is 9900. There is no published GPS MEA (which would appear in blue with a G appended to the altitude). But if you are flying with an IFR-approved GPS, ATC could clear you to 9900, if, for example, you encountered ice.

Similarly, along V120 east of MLP, the MEA is 13000 and the MOCA is 9600, potentially giving you more than 3000 feet to work with if necessary.

Note, however, that not all airway segments have published MOCAs. For example, the only published IFR altitude between PUW and MLP is the MEA of 9100. You still might be cleared below that MEA if ATC has lower minimum IFR altitudes or minimum vectoring altitudes available in that area, but those altitudes are not typically published on charts that pilots use.* You would just ask for a lower altitude, and the controller could clear you to the appropriate MVA or MIA.

The updated FAA handbook specifically notes that controllers may clear you to an MVA or MIA, but they must also issue lost communications instructions:

(a) In the absence of a published MOCA, assign altitudes at or above the MVA or MIA along the route of flight, and

(b) Lost communications instructions are issued.

*You can download MVA and MIA charts as PDFs from the FAA website, here. But at present, these charts are not available in a format that allows for easy integration with apps that pilots typically use or for straightforward comparison with other aviation charts.

A Quick Way to Search for GPS NOTAMs

The FAA NOTAM search site ( provides the quickest way to find GPS NOTAMs that alert you to disruptions in the satellite-based navigation system. If you’ve ever tried to find and sort through the text descriptions of these alerts, you’ll appreciate the lists and map views that show how GPS tests and other issues may affect your ability to navigate using GPS.

To learn more about using the FAA NOTAM search site, you can download the User Guide from the FAA website or from my Aviation Documents folder at OneDrive.


To find GPS-related NOTAMs at the FAA website follow these steps:

After acknowledging the disclaimer, on the main page, select the Predefined Queries option and choose GPS.


Click the Search button, and you’ll see a list of GPS NOTAMs.


You can also show the NOTAMs in a table.

Or in a table with an adjacent map.

You can filter the list to show only the NOTAMs effective in one or more air route traffic control centers.


And you can zoom in on the map and click a NOTAM flag to see more information about that notice.



Use the +/- buttons in the upper-left corner of the map to zoom in and out. To print a NOTAM, click the print icon next to the text.

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.

Avoiding Confusion when Flying GPS Legs

Garmin has published a useful document on the topic of the types of legs that appear in various instrument procedures.

For example, many departure procedures include fix-to-altitude legs.


GNS 400(W)/500(W) Series and GTN 6XX/7XX Series Instrument Procedure Leg Awareness (PDF) is a good summary of key types of legs that are used in DPs, STARs, and approaches, and it describes the features and limitations of the GNS and GTN units.

You can also find information on IAP legs in Chapter 6 of the Instrument Procedures Handbook.

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

When a VOR is Decommissioned

The recent shutdown of the Lake Henry VOR (LHY), which lies northeast of Wilkes-Barre PA (VFR chart at SkyVector here), is an example of how the FAA is handling the gradual decommissioning of VORs. (See also More Details about VOR Shutdowns)

As the latest IFR low-altitude en route charts show, the VOR (at present still depicted on the charts to help pilots become familiar with the new routes) has been replaced by a five-letter waypoint, LAAYK.


Note that the frequency for the VOR (110.8) is now shaded to indicate that the facility has been shut down, as described on p. 54 of the Aeronautical Chart User’s Guide.


A wider view of the area shows that several victor airways or segments of airways have been replaced with T-routes, depicted in blue on charts published by the FAA.


T-routes and their associated G (GPS-based) MEAs are described in AIM 5−3−4. Airways and Route Systems and in “Area Naviation (RNAV) ‘T’ Route System” on page 56 of the Aeronautical Chart User’s Guide (12th edition).

You can expect similar changes as more VORs are shut down over the next several years, leaving what the FAA calls the Minimum Operational Network. That plan at present calls for all VORs in the mountainous regions (essentially the western U.S.) to remain online, while many VORs elsewhere in the country are decommissioned.