Gadget Flight Rules

For any cockpit gadget to be a safe primary or back-up device, the PIC must know its capabilities, requirements and limitations.


One thing we should have learned during our primary training is to always have an “out” or backup plan for when things don’t go according to plan. On any given flight, I typically have a smart phone with various aviation apps, an iPad with even more, a mounted Garmin 396 and a handheld radio. I would say most pilots have at least one, if not several of the above. Most of the time, everything in the panel works well and I can fumble my way to the destination without too much assistance from the portable devices surrounding me.


But every now and then, we need a little “help.” The need can stem from a failed vacuum/pressure system and unreliable gyros, a total or partial electrical failure or simply a single instrument giving erroneous indications. Without going into too many specifics about hardware, brands and apps, let’s step through what it takes for an appropriate portable or handheld device to be a functional backup in your time of need, something I call “gadget flight rules,” or GFR.

Flying GFR
Imagine flying along in IMC and losing one of your electrical, vacuum/pressure or static systems. Can you get your bird safely on the ground relying exclusively on non-FAA-approved gadgets? In theory, yes. Portable devices try to replicate what you see in glass panels, but without all the messy—and costly, time-consuming—FAA approval process required for instruments and equipment in certified aircraft.

As an example, I recently downloaded several apps for iOS devices (Apple iPhone and iPad products) that work like and strongly resemble the Aspen PFD mounted in my Cessna 206. One of them, in fact, offers synthetic vision for $29. Such an upgrade would cost $3000 for my Aspen.

Clearly the gee-whiz gadget version for my iPhone isn’t certified as a primary instrument, but for one percent of the price for similar capability in the Aspen, it has my attention. Could GFR be a backup for a catastrophic instrument failure?

Not-so-Handy Handheld
My first lesson on the proper care and feeding of portable devices in the cockpit came courtesy of a handheld communications radio. The portable aviation transceiver came with my purchase of a 1945 Piper J3 Cub lacking an electrical system. Before my first flight in the J3, I charged the battery, hooked it up to my headset and called ATC. Nothing. I tried again. This time tower came back with “aircraft trying to contact ground, transmission is unreadable.”

The issue turned out to be my antenna; rather the lack of a connection to an external one. Once the handheld was connected to the aircraft’s external antenna, I was able to establish two-way communication.

The next issue was battery capacity. When the battery was fully charged, my transmissions were intelligible, but after longer flights, the radio lacked the “oomph” to transmit clearly. Fortunately, I had a plan B, along with a Plan C.
Plan B was a spare, fully charged battery pack for my transceiver. Plan C was relying on my cellphone, through a Bluetooth-enabled headset and with the tower’s telephone number programmed in ahead of time. When the handheld signal wasn’t strong enough to reach the tower, I had the ability to contact them by phone and arrange light-gun signals. 

I now routinely use my handheld in the J3, but it’s hooked to an external antenna, powered by an external battery, a spare battery is in-hand and I always have my cellphone at the ready. All of which highlighted for me that I must be capable of understanding any portable in-cockpit device’s capabilities or it will simply be something to fumble with on the way to the crash site.

For any piece of electronic gear to be a meaningful backup, it needs to have enough power available to last the duration of the planned flight, including diversion to an alternate airport and some reserve. If you haven’t already noticed, battery levels on gadgets in-flight seem to drop faster than a plane in a spin. The reasons are somewhat obvious.


In aviation use, the screen is always on and, in daylight conditions, at full brightness. Also, the GPS and cell antennas will be at full power, struggling to hold satellites and shake hands with cell towers. Moving maps and constant screen redraws will tax the processor on your gadget, too.

As one result, don’t expect the product’s advertised 10-hour battery life in the cockpit. To avoid anxiety, do some advance battery testing to know your particular gadget’s longevity under real-world flight conditions. Whenever possible, obtain the appropriate adapters and plug the device into ship’s power. See the sidebar at right for some additional thoughts.

Mounting and Ergonomics
Any device that might become a critical instrument in an emergency needs a good mounting point in an appropriate location. Too far from your normal scan and you are itching for disorientation. Loose or poorly stabilized mounts might shift during flight, or worse yet, interfere with critical controls. This goes double if power cords are involved. And it shouldn’t block your view of other devices or areas of the control panel.

Good mounting could save your life. I once had an aerial photography monitor slip from its original mount position enough that it interfered with my yoke. The issue presented itself while in a turn. The jammed monitor kept the aircraft in that turn until I beat it to the floor.

After gadgeting-up your cockpit, you should double down on ensuring flight controls are “free-and correct,” being mindful of where the gadgets might end up if the mounting system fails. Also, keeping gadgets unmounted but accessible (e.g., on the seat next to you) makes them potential projectiles in turbulence.

Following Murphy’s law, if a loose gadget falls, it will inevitably find itself repositioned in the worst possible location. That’s what happened to a Mooney pilot on January 2, 2011, while approaching the St. Petersburg-Clearwater International Airport (PIE) in Clearwater. Fla. Thanks to a worn boot with a hole in it, a small flashlight “jammed between the aft side of the aft nosewheel well bulkhead and the landing gear bellcrank, adjacent to the aileron control linkage and below where the Johnson bar went through the deck,” according to the NTSB. The flashlight was found only after it prevented landing-gear extension and resulted in an uncommanded, 60-degree bank.

Aviate, Navigate, Communicate
A useful way to group non-certified backup systems is by functionality, following the tried and true catch-phrase “aviate, navigate, communicate.” Any time a device is subbing in for a primary instrument like airspeed, altitude, attitude or heading, its primary function is to help you aviate. Gadgets that help you get to your destination, shoot your approach or know with confidence where you are with respect to airports and terrain fall into the category of navigate. Devices helping you reach out and touch someone in the outside world fall into the last category, communicate.

When I get disoriented in IMC, the three things I struggle with are keeping the wings level, staying on course and holding the right altitude—in other words, flying the airplane. The instrument rating’s purpose is understanding how to deal with these three challenges without outside references. It’s a hard enough task when everything in the panel is working and playing well with each other: It’s going to be plenty challenging to make it safely to the ground flying GFR. The key is to be prepared.

If gadgets are your backup systems, you need to know which device will play each role. An in-flight emergency is not the time to find the right spot to mount your iPad, nor is it the best time to pick which app is your favorite for keeping your wings level or holding altitude. Backup systems must be known, not guesses. You will need to know which gadget you will be using for each function.

Wings Level
For me, keeping the wings level is the first order of business. There are many alluring surrogates for attitude indicators, artificial horizons—even synthetic vision—but I found all had significant lag compared with my actual gyros. Obviously, you will need to decide how to do this substitute based on your own suite of gadgets.


It is important to note that apps mimicking artificial horizons need to be calibrated after mounting and before taking off. I also found they tended to drift while in flight. If you plan on using a gadget-based attitude indicator of some kind, test and cross-check it with your operating instruments—in good VFR with a safety pilot!—to decide if its performance is good enough to be a worthy backup. None of the artificial horizon apps I tested were good enough to meet my standards, so when simulating the worst-case instrument failure, I rely on heading trends rather than artificial horizons to keep wings level.

Heading, Altitude, airspeed
This truly is where gadgets shine. If you can keep the plane on a heading or following a straight course line to your destination, your wings are level. This is a basic GPS/moving map function, but don’t underestimate the value of having this information when all other instruments have failed. If you prefer round gauges and needles to magenta lines, there are many apps providing virtual VOR and HSI indicators.

Meanwhile, chances are you don’t have a spare barometric altimeter. There is an excellent chance, however, you have a device providing GPS-based altimetry. Be fully aware, however, that it’s not at all uncommon to see disparities of plus or minus 100 or even 200 feet on less-expensive GPS receivers. That’s okay when you’re at a safe altitude, but closer to the ground, you will need to add fudge factors to avoid kissing granite.

Dry-run your own systems and cross-compare your aircraft altimeter readout with your particular GPS(s). You may find a systematic error varying between high and low barometric pressure, or you may simply find the devices are off by 100 feet or more either way. The key is knowing if you lose your altimeter and have to rely on your GPS gadget alone, how much you will need to distrust and compensate, particularly on an approach.

Gadgets give you groundspeeds, not airspeeds. To derive an airspeed, you’ll need to mentally compensate for the direction and magnitude of the wind and the effect altitude has on true airspeed. This is one reason it’s good to know the winds at your departure and destination airports and the winds aloft along your route. If they are printed out or on your kneeboard, you will be a bit safer. If you can’t remember the precise winds, try to at least remember the basic cardinal direction and an order of magnitude so you can work backwards to maintain a safe airspeed. Above all else, do what you need to do to assure a safe airspeed, particularly when maneuvering close to the ground.

Navigate an Approach?
There are a myriad of Android, iOS and GPS systems that will find the nearest airport for you. A similar number will mark it with a nice line in your choice of colors. The caveat is the gizmos are only as good as your ability to use them. Dry runs at home at 1G and zero airspeed will pay back many times over. When out flying with a safety pilot on board, have a testing plan to see if you can make it work while under a flying workload.

The biggest challenge, if you’re in IMC, is not finding the airport, but getting safely to the ground. This is where I recommend taking the time on your next outing under the hood with a safety pilot or your next IFR currency flight to take the no-instrument instrument-GFR approach challenge: Try to fly an approach with only your non-FAA-approved backup system as your main guidance.

I really can’t tell you how to do it with your particular suite of gadgets, but you should know which gadget to use in a primary role and which is secondary. Then go out and practice to get your system dialed in. I flew two approaches strictly using the Garmin 396, plus another using my iPad with geo-referenced approach plates with the Garmin 396 to cross-check altitudes and fixes. I found one of my best gadgets for this exercise was having a paper copy of the approach plate. I kept the airplane where it needed to be on the geo-referenced plate while briefing altitudes and step downs off the paper copy. I made it safely to the ground by GFR.

Lessons Learned
Aircraft are safe in part because they have backup systems. Aircraft equipped for IFR have instrument and navigational redundancy for a reason. When the electrical system soils the bed, the engine still runs because it relies on magnetos.

If the vacuum/pressure system fails, you still have the whiskey compass to determine heading and the airspeed indicator/VSI/altimeter/turn instrument to help determine attitude and keep the wings level. If your aircraft is all-electric and IFR-capable, you probably have dual batteries and dual busses.
Even all-glass airplanes will have—ironically—”steam-gauge” backups. They may not be conveniently mounted however, and using a gadget might be preferable than leaning over the cabin and inviting vertigo.

Unfortunately, systems can still break and accidents often result from a series of unfortunate alignments where multiple systems fail at the same time or sequentially. If you’re planning to fly in challenging conditions—and even if you’re not, but want the comfort of redundancy—your gadgets might be your last backup. But they are only as good as your ability to use them, and that requires preparation and practice.

Mike Hart is an Idaho-based commercial/IFR pilot with 1000 hours, and proud owner of a 1946 Piper J3 Cub and an aerial photography equipped Cessna 206.




  1. Thanks for this wonderful article. One more thing to mention is that a lot of digital cameras can come equipped with some sort of zoom lens that enables more or less of your scene to be included by ‘zooming’ in and out. These kind of changes in focusing length tend to be reflected from the viewfinder and on large display screen at the back of the very camera.


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