Buying your first skydiving altimeter
Buying your first skydiving altimeter
Buying your first skydiving altimeter explained.
Buying your first set of skydiving kit is both a proud moment (as it usually means you are close to or have already passed the course) and a daunting prospect.
Why Use One?
The use of an altimeter is a required device under the BPA rules and regulations (Section 4.1 of the BPA Operations manual (p.48)), and you'll see every skydiver wearing one in the UK.
There are exceptions to this if you are making less than a 15 second delay, which is why you'll see the static line and short delay students on the RAPS courses jumping without one.
New or Used?
There's no reason NOT to buy a second hand altimeter, but there ARE things to check for. Mechanical ones are more prone to damage that might not be apparent when looking at it - so make sure you get a guarantee that if the altimeter isn't fully functional, you can return it. Check a digital one - put a new set of batteries in if needed, most have a self test at the start.
In all cases - take your new altimeter up with a known working one for a comparison. Ask the DZ staff nicely to borrow one, or ask an instructor to compare it for you.
What are the different types?
This basically boils down to two main categories. The analogue and digital. Although both use the same principles of changes in air pressure to display the altitude. Other types of altimeter technology exist and can use GPS signals or other reference material such as radar or laser - however these are normally very large and used on aircraft.
The 'analogue' altimeter is a purely mechanical device that uses barometric pressure (different amounts of air pressure) to move a needle around a dial face. These analogue altimeters are commonly seen worn on the wrists of students during their training and if you look at the pilots console you'll see an analogue altimeter there too.
Digital altimeters work on the same principle as their mechanical counterparts, however instead of using a physical diaphragm which changes the position of the needle, the device uses an electronic chip that reads the atmospheric pressure.
This information is then displayed on the altimeter - normally on an LCD front face, although there are many options available. Digital altimeters require batteries, but are generally less susceptible to damage causing knocks and bumps as they rarely contain any moving parts.
(Manufacturers website opens in a new window)
How do they work?
The mechanical altimeters are actually aneroid barometers - that is to say they operate on air pressure, but have been calibrated to show the altitude instead.
The changes in air pressure are displayed via an digital front face, or by the movement of a needle on a dial face. The lower the air pressure, (the higher up you go) the more altitude is shown to the user. As the skydiver descends the air pressure is increases and the needle or counter will move back towards zero.
Digital altimeters will normally 'self-calibrate' meaning that they can identify when they are on the ground, where as the mechanical ones need to be manually set before each jump.
The most popular mechanical altimeter in the UK market is the Altimaster Galaxy, made by Alti-2; However most mechanical altimeters used in skydiving have a similar appearance.
The larger versions of the original mechanical altimeters are still quite popular with the CRW (Canopy Relative Work) and Wingsuit pilots. The larger face and mount options makes them easier to attach on a pad and affixed to the chest strap. This negates the use of the canopy pilot and wingsuit pilot having to make arm movements.
Alti-2 Wrist mounted altimeter.
Altimaster - Altimeter mounted on a 'pillow'.
An FT 50 altimeter with wrist mount option.
Mechanical altimeters are delicate instruments and can suffer damage from hard knocks and bumps. Damage may not be apparent until it's being used, with erratic needle movement, sticking or erroneous readings being some of the most common faults.
The average cost of a simple mechanical altimeter is around £100 and can be found via our web store here.
The digital altimeters come in a wide range of options, and most have additional features incorporated into them. Almost all digital altimeters are capable of swapping between various measurements such as measuring in FEET or METERS, so purchasing one from abroad generally isn't a problem.
Digital altimeters can take comparatively more abuse compared to the mechanical variants, however the screen is most suseptible to damage from sharp objects and can even shatter or split from a hard knock. Whilst this might render the display unusable, the internal electronics often continue to function the other parts such as audible alarms.
It's worth noting that whilst the device has the appearance of a mechanical altimeter, it is a hybrid form and fully digital (with a built in digital log book) the needle is controlled digitally, and will self calibrate to zero when on the ground.
The cost of a digital altimeter varies between altimeter only (such as the L&B Viso) type models to multi-functional devices (such as the Alti-2 N3)
Which model you pick will depend on how careful you are with your equipment, how much you are willing to spend, and what you like the look of.
Our only suggestion is for people looking for their first altimeter - don't purchase the altimeter watch in the UK - you might find your local DZ don't let you jump with it!