Skydiving is an inherently risky sport that can lead to injury or death. Freefall Data Systems LLC products are intended for use by trained skydivers following the Basic Safety Requirements and General Recommendations of the USPA or their national governing body.

When functioning and used properly, altimeters can greatly enhance a skydiver’s altitude awareness. However, all skydiving equipment is subject to failure and malfunction, even when properly assembled and used. For this reason, altimeters should only be used as a secondary indication of altitude—secondary to a visual ascertainment. Freefall Data Systems LLC altimeters are altitude-awareness aids only; they are not automatic activation devices, do not deploy a parachute, and must never be relied upon as the sole basis for deployment decisions. It is possible that any altimeter could read higher than you actually are above ground level. Many factors can compromise the accuracy of an altimeter; do not ever rely on one to save your life. As should be taught in every First Jump Course, each skydiver is solely responsible for his or her own altitude awareness and safety on each skydive he or she makes. Many distractions can occur on a skydive; just because you are wearing an altimeter, it does not mean that you will necessarily register the information it is intended to convey.

Temperature affects every barometric altimeter. Barometric altimeters do not measure height; they measure air pressure and convert it to height using the International Standard Atmosphere, which assumes a particular temperature at every altitude. Real air is rarely standard. When the air is colder than standard, it is denser, pressure falls faster with height, and the altimeter reads higher than you actually are—the same effect pilots learn as “from hot to cold, look out below.” The error grows with height above the point where the altimeter was zeroed: roughly 4 feet per 1,000 feet for every 1 °C (about 2 feet per 1,000 feet per 1 °F) that the air column is colder than standard. Freefall Data Systems LLC barometric altimeters do not compensate for this, and no device that measures only pressure can; a temperature sensor inside a device on your body cannot know the temperature of the air column beneath you. The altimeter in the cockpit of an aircraft is a barometric instrument using the same standard atmosphere, so on a cold day the pilot’s altimeter, the transponder’s reported altitude, and the jump-run altitude called over the intercom all carry the same over-read. Agreement between your altimeter and the aircraft’s is not confirmation that either is correct. Assume that every barometric altimeter and barometric automatic activation device shares the same error.

Audible altimeters use high sound pressure levels in order to cut through noise and can cause hearing damage. For this reason, Freefall Data Systems LLC recommends wearing earplugs when using any type of audible altimeter and for general hearing protection while skydiving. Visual altimeters and signaling lights can obscure or impair vision. Never place a light directly in front of the eye, as it will obscure vision and compromise depth perception. If a light is not placed correctly or is not set to a brightness appropriate for the conditions, its indications may not be seen. During night jumps or any low-light conditions, set the brightness extremely low so as not to reduce your own or others' low-light vision.

Freefall Data Systems LLC's altimeters contain a lithium polymer battery; do not use a device if its case is damaged in any way. Charge only from a standard USB power source, do not leave a device unattended while charging, and do not expose it to extreme heat. Never puncture or incinerate a device, and dispose of devices and batteries in accordance with local regulations.

Verify that your altimeter is functioning correctly before each jump, and remove a malfunctioning or damaged device from service immediately. Do not open, modify, or attempt to repair a device yourself; unauthorized modification or repair can create a hazard and voids the warranty.

Read and follow all instructions found for your product at freefalldatasystems.com. Failure to follow instructions could imperil you or others. Use of any Freefall Data Systems LLC product is subject to the Warranty & Limited Liability Agreement.

(Updated August 27, 2026)