Flying Ad-Hoc Holds with a GTN 750
February 6, 2016 9 Comments
Garmin plans to release updated system software (version 6.x) for the GTN series of navigators in February 2016. The software includes several new features, including the ability to create an ad-hoc hold at any fix.
To learn about and practice using the new features, download the latest version of the free GTN 750 PC Trainer Lite from Garmin. The download includes updated manuals (PDFs) for the GTN series avionics that describe the new features in version 6.x.
I have experimented with the new holding features in the simulation, and it seems simple and intuitive.
Creating a Hold (as Published)
Suppose, for example, that ATC clears you to hold as published at an en route fix such as CARRO intersection, located southwest of Seattle along V27.
As this close-up view shows, a standard (right turns, one-minute inbound leg) holding pattern is charted southwest of CARRO at the 24 nm DME fix on SEA 230 radial (or the intersection of the SEA 230 and OLM 346 radials).
That en route hold isn’t in the GTN 750 database, however (it’s not part of an departure, arrival, or approach). If you were flying along V27 with the current version of the GTN system software and instructed to fly the hold, you would proceed to CARRO, select the OBS feature, set the inbound course on your HSI to 050 degrees and fly the hold using the heading bug and a timer.
The forthcoming software automates that process, as the following captures from the GTN trainer show.
Assume you’re flying V27 northeast, toward SEA.
On the flight plan page in your GTN 750, touch CARRO (one of the fixes along the airway). The Waypoint Options menu appears. Hold At Waypoint is one of the new options.
Touch Hold at Waypoint. The Hold at Waypoint menu appears.
Touch the appropriate buttons (Course, Direction, Turn, etc.) in series to enter the information required to fly the hold as cleared by ATC. As you can see, the Hold at Waypoint menu includes options such as Direction (to specify either the inbound or outbound course to or from the fix), Leg Time (or Distance for RNAV or DME holds), Turn (direction of turns in the hold), and Expect Further Clearance time (which sets a reminder that will appear when the EFC time arrives).
When you finish entering the required information, touch Load Hold. The GTN adds the hold as a waypoint in your active flight plan.
When you return to the map screen, the GTN 750 shows the hold you created drawn on the map.
As you continue inbound to the holding fix (CARRO), the hold becomes the active leg in your flight plan, and, because this is a timed hold, an automatic timer appears on the CDI display.
Note that GTN 750 enters SUSP mode as you enter the hold. And as you proceed outbound, the timer begins counting up as you pass abeam the fix on the outbound leg.
The timer resets as you join the inbound leg.
When you are cleared to leave the hold, touch the CDI display to return to the flight plan page, select the next fix in your route (or enter a new fix, depending on your clearance), and proceed. The GTN 750 switches out of SUSP mode and resumes normal waypoint sequencing.
A True Ad-Hoc Hold
The preceding example shows how to add a published hold along an airway to a route. Now let’s try a true ad-hoc hold at a fix specified by ATC.
Assume you’re southeast of Seattle, heading roughly north en route to Boeing Field (KBFI).
ATC clears you to hold at BLAKO intersection, as shown below. Your instructions are to hold north of BLAKO on the 340 degrees course (160 degrees inbound), 4 nm legs, right turns, with an EFC of 2001 UTC.
On the flight plan page, add BLAKO as a waypoint (if it’s not already in your flight plan), and then touch BLAKO to display the Waypoint Options menu.
Touch each option and fill in the appropriate information to specify the hold. Then touch Load Hold.
The hold you created appears in the flight plan…
And on the map, complete with the recommended entry procedure.
If your GTN 750 is connected to an autopilot with GPSS capability, the autopilot can fly the entire hold, including the entry. Because this hold is based on distance, not time, the GTN 750 doesn’t show a timer on the CDI. Instead, it prompts you to turn inbound at the appropriate distance outbound from the holding fix.
I look forward to updating the GTN 750 in my Bonanza. I might even look forward to flying holds.