Affordable, Portable EFIS: Dynon’s D1 Pocket PanelWritten by Charles Lloyd
Who should have it, where to install it, and how to fly with it-
If your panel looks like the photo on page X (Figure 1) when you’re flying in instrument conditions, then it’s time to consider a backup plan so you’ll arrive safely at your destination.
The Dynon D1 Pocket Panel (Figure 2, page X) is a solid-state AHRS coupled with an internal GPS to provide GPS altitude and ground speed. All of these capabilities are packed in a 3.6 x 3.26 inch package—including a lithium battery that will power the D1 for up to four hours.
The D1 is not certified for permanent installation in a Part 23 aircraft. However, Dynon provides three methods to temporarily mount the D1 Pocket Panel (in similar fashion to mounting handheld GPS devices).
There is a suction cup with an adjustable arm to mount the D1 on the windscreen or to the top of the panel; a holder that mounts in an empty three-inch instrument hole; and a holder that comes with screws to attach the holder to the panel.
Accessories include a 110 volt wall outlet charger and a 12/24 volt charger that will plug into your aircraft’s utility outlet.
The D1 contains its own internal GPS antenna. If the signal is not adequate from the cockpit location, then there is an external GPS antenna with an extension wire to permit placing the antenna in a more open location.
Turn it on
I opened the shipping box, set the D1 on my desk and pressed the on/off button on top of the unit. The power-up first displayed the “Be Careful” screen, which I acknowledged by pressing the adjustment button on the right side of the unit. In a very short time the Attitude and Heading Indicators (AI and HI) appeared and also displayed the local altitude and zero ground speed.
Pressing the adjustment button puts the AI in pitch adjustment mode where toggling the adjustment button up and down will adjust the pitch attitude to show the correct reading. Pressing the adjustment again and toggling the button will correct any roll error.
Who needs the Dynon D1?
Many Cessna Flyer readers fly Cessna 172 aircraft in instrument conditions using classic six-pack vacuum-driven instruments. The Dynon D1 provides a simple no-nonsense backup to get out of instrument weather. It should be considered an advisory instrument to use when other equipment fails.
The typical AI and HI get power from a single dry vacuum pump. If you are an instrument rated pilot that counts on a single dry vacuum pump to operate continuously, you’re rolling the dice every time you fly—sooner or later, the dry vacuum pump will fail.
Sure, we are supposed to be able to recover with needle, ball, airspeed— plus some help from the altimeter. However, wouldn’t it be nice to have an advisory instrument to supplement all the certified instruments that still operate? Remember, this is an emergency situation if there ever was one, and you want all the help you can get. The key is to place the D1 in a location where it is easy to include in normal your scan.
Where to install the D1
I took the D1 out to my airplane’s cockpit and held the unit here and there, looking for the best spot to place it in case of an attitude instrument or vacuum failure. The obvious place to me was above the “failed” attitude instrument.
Oh dear, Dynon doesn’t make a holder that fits this situation, and there is no space near a typical normal scan in the left panel! So I devised a fourth installation method: self-adhesive Velcro above the attitude instrument (see figure 3, page X) and on the back of the D1 (see figure 4, page X).
Next, I needed to figure out a standby mounting location for the D1—somewhere nearby to hold the unit, allow me to power it up and attach it to a charging source. With a panel full of all kinds of good stuff, I chose Velcro in the lower left panel (photo on page X, figure 5) as my answer.
There is one consideration though: moving the D1 from one position to another will upset the AHRS and cause the display to momentarily lose proper attitude orientation. Recovery takes approximately six seconds.
Okay, so you’ll have to use needle, ball and airspeed for 10 seconds or so. The key is that the D1 needs to be positioned in the vicinity of your normal scan (see Figure 6 photo) to be most useful as an advisory instrument.
Confirm that the pitch and roll are adjusted properly in the new location. If the D1 is positioned in the standby location just as it will be in the in-use position, then there should be no problem. If you’re using the Velcro attachment method, then a small aluminum angle attached vertically to the instrument panel can be an alignment point for both standby and in-use positions.
Flying the D1
As part of the pre-startup procedure I placed the Dynon in its standby location and attached it to the utility electrical outlet. I turned on the D1 and confirmed proper attitude and roll.
Once airborne, I moved the D1 from the standby location to the Velcro mount over the “failed” attitude indicator (see Figure 6). Cross-checking altitude, heading and ground speed with the instruments left, below and right of the D1 showed a good correlation between the D1 and installed instrument values.
If, in addition to a vacuum pump failure, the aircraft simultaneously suffered alternator failure and loss of the altimeter and airspeed indicator, then a D1 Pocket Panel has enough information to help you get down below the clouds.
A nice feature included in the D1 is the magenta leader display (shown in Figure 7, page X) that indicates where the heading will be in approximately six seconds; it’s a nice feature to use for rolling out of a turn. The altitude screen shows this same “anticipation style” for climbs and descents.
The Dynon D1 Pocket Panel deserves serious consideration as part of your flying kit, particularly for instrument flying in any single vacuum system aircraft. The D1 provides all the necessary information to advise you how to get out of one of the most stressful conditions I can imagine: loss of instruments while in instrument weather.
What’s the cost? The whole kit cost is $1,425. The good part is that the Dynon D1 provides this advisory service at 10 percent of the cost of other certified units on the market today. At that price, it’s a bargain—and may be an investment that saves your life someday.