We all know there are some hot debates in our sport: RSL or no RSL, AAD dependency, and exit separation are well-known dead horses. Another topic certainly worthy of discussion is the choice between analog and digital altimeter displays. Asking that question will yield a variety of opinions (no surprise there) and will likely be inconclusive.
First, a clarification: this discussion revolves around the altimeter display, not the underlying hardware. Altimeters with mechanical internal aneroid capsules have analog displays; those with electronic pressure sensors can have either a digital or analog display. Now that we have cleared that up...
Analog dial faces of all types commonly have numerical graduations and colored segments to indicate the status of what is being measured. Alti-2’s Altimaster Galaxy, for example, is first graduated in thousand foot increments starting at the 12 o’clock position (zero). There are yellow and red caution zones placed at commonly used altitudes to provide a visual warning at a glance. Digital displays, like Alti-2’s N3, provide a numerical altitude reference. N3 provides a three-digit decimal altitude in free fall and four digits under canopy. So – which is better? It really boils down to three things: familiarity, specific application, and personal preference.
Many skydivers stick to what they learned to use as students. Later in their skydiving career they may choose to “re-train” that familiarity and transition to a digital display. I did so myself when Neptune hit the market nearly ten years ago and have been a huge digital display fan since then.
Application brings a different frame of reference entirely. Let’s take a look at two commonly used analog dials, starting with the temperature gauge in your automobile. My dear old Dad taught me to look at my gauges periodically like a pilot does cross-checks. A quick glance at the temperature gauge should show the pointer dwelling just slightly left of center, or about 40% of its travel. I have no earthly idea what specific numerical data that conveys – I glance at the gauge, my brain processes the placement of the needle based upon my training, and I know that I am good to go! Now consider the gauge on a fire extinguisher which contains a small green segment and a large red segment. A quick glance reveals the pointer dwelling in the green or the red – good or no good. In both of these cases, an analog display is preferable to the way I do business.
What about skydiving? From day one we are asked to apply specific action to specific performance altitudes. As an AFF Student, we may be taught to recognize 5,500 feet on our altimeter to trigger a critical action: wave off and pull. It can be argued that the direct conveyance of that numerical data from a digital display eliminates the need for the brain to convert the pointer’s indication on an analog dial face into numbers for an action to be triggered. If an AFF Student recognizes 5,500 feet on his digital display, it directly sends him into action.
Then there is personal preference. Electronic altimeters with a digital display often have other features like logbooks, timers, and the like that take more time to learn. Some skydivers just love the simplicity of turning a knob to zero the pointer and off they go.
Mechanical/analog altimeters are usually more economical for skydivers on a budget. Electronic devices require power from replaceable or rechargeable batteries; mechanical devices do not. There are several other advantages and disadvantages regarding the mechanism which can also drive personal preference. Factor in accuracy, calibration requirements, form factor, mounting options, ability to read altitude in low-light or darkness, waterproofing, convertibility between visual and audible, and others – the decision becomes more complicated.
So, if you are in the market for an altimeter, or are thinking about switching from analog to digital, I suggest you try them both. Put your trusty Altimaster II in your helmet bag and borrow an N3 from a friend or even your local gear store. Make a few jumps reading digitally conveyed numerical altitude and see what you think! In the meantime, I will be thinking about what advances in technology might be on the event horizon.
John Hawke (slotperfect) is General Manager of Alti-2, Inc. in DeLand, Florida, USA