Are you considering upgrading your analog avionics to digital avionics? Avionics upgrades can increase the value of your aircraft, but knowing exactly where to start can be a challenge. Whether you want to convert to a fully glass, digital panel or simply upgrade from legacy analog equipment to newer, more reliable analog avionics, we’ve got everything you need to make the most informed decision.
Understanding the Six Basic Aircraft Instruments
There are six main flight instruments that ultimately provide an aircraft operator with the current information on aircraft speed, altitude, climb/descent, attitude, heading, and turning/banking. Individually, those instruments are:
- Airspeed Indicator (ASI)
- Vertical Speed Indicator (VSI)
- Attitude Indicator (AI)
- Heading Indicator (HI)
- Turn Coordinator (TC)
The instruments in this “six pack” are often powered by various aircraft systems. The ASI, altimeter, and VSI use a pitot-static system. The pitot-static system provides ram air pressure from the pitot tube and ambient pressure from the static port. The ASI is the only instrument that uses the pitot tube, while the ASI, altimeter, and the VSI all use the static port.
These instruments are powered by vacuum, pressure, or electrical power.
The airspeed indicator uses pressure differentials to measure and display the aircraft’s speed. Typically, speed is displayed in knots or miles per hour.
A needle will point to the aircraft’s current air speed, and color-coded notches offer critical speed information based on the specific aircraft’s stall, flap setting, normal operating, caution, and max speeds.
Airspeed Indicator Inner Workings
The altimeter relies on barometric pressure from the static port to display the aircraft’s altitude or height above mean sea level in feet. Because barometric pressure changes as altitude and atmosphere changes, most altimeters contain the ability to adjust based on local barometric pressure.
Vertical Speed Indicator
The vertical speed indicator indicates how fast the aircraft is climbing or descending. Using internal pressure differential, a diaphragm connected to the static port expands or contracts in response to the climbs or descents. A hole in the diaphragm releases the pressure change to return to zero when no change is occurring, or the aircraft is maintaining the same height without climbing or descending.
Vertical Speed Indicator
The attitude indicator is also known as the artificial horizon and it displays the aircraft’s attitude relative to the horizon.
A vertical scale across the horizon shows decrees of pitch, and a curved scale across the top shows degrees of bank. If the aircraft changes pitch or direction, the display responds accordingly.
The heading indicator displays the current compass direction (also referred to as the heading) in which the aircraft is flying. The heading indicator displays a 360-degree compass with headwinds in 5-degree increments.
Most heading indicators also include an adjustment knob that turns the internal HI compass card to align with the aircraft’s magnetic compass.
The turn coordinator displays the initial roll rate as well as the stabilized rate of return. A silhouette of the aircraft shows on the instrument and displays the direction of the turn, and will align with a mark on the display if the aircraft is turning in a standard rate.
Which is Better: Analog Avionics or Digital Avionics?
There are pros and cons to having a completely analog avionics system, a completely digital avionics system, or a mix of the two.
If you’re not ready to make the commitment to an all digital avionics system, there are newer analog components that you can choose from instead. The benefit of upgrading at least to newer analog avionics instruments is parts availability and ease of maintenance, should something break or need attention. However, parts are more readily available for digital avionics instruments versus analog.
From a cost perspective, the initial cost to install newer analog avionics will be lower, but your ongoing maintenance costs will be higher. On the flipside, initial costs to install digital avionics will be higher, but ongoing maintenance costs will be lower.
The decision ultimately comes down to what aesthetic you prefer, what your initial install budget is, and what your comfortability is with digital versus analog avionics instruments.
Regardless of your choice, our avionics experts are here to help. Our proven track record of avionics installs and maintenance will make us a great partner for your next avionics upgrade project.