Atmo is the wind and vario engine inside the Era. It measures the air you are flying through in three dimensions: which way the wind blows, how fast, and how quickly the air itself is rising or sinking around the glider. It needs no compass, no second GNSS antenna and no extra probe — only the sensors an Era already carries.
Atmo is built into the Era 57 Gen 2, which leaves the factory with its licence installed. On a first-generation Era 80, Era 57 or Era essential it is a licence for the instrument you already own; activating Atmo on your Era covers that step by step. Atmo is also coming to the Navia Sense sensor unit. This article explains what Atmo measures, how it does it, and where its limits are.
The wind triangle, in three dimensions
Every wind calculation in gliding rests on one subtraction. The GNSS receiver measures how the glider moves over the ground. The airspeed system and the glider's attitude describe how it moves through the air. Whatever is left over is the air moving:
ground velocity = air velocity + wind
A classic wind calculation solves this flat, in two dimensions. Atmo solves it in three. GNSS gives the ground velocity including the vertical speed, so once the air velocity is known in three axes as well, the leftover has a vertical component too: the vertical motion of the airmass. That third number is what a glider pilot calls netto — the rise or sink of the air itself, with the glider's own motion taken out.
What a classic wind calculation can and cannot see
The airspeed indicator tells you how fast you fly through the air, but not in which direction. Without a direction for the air velocity the triangle cannot be closed in one step. A classic calculation — the Era's own included — works around this. It gets its best estimate when you circle: over one full turn the glider points in every direction once, its own air velocity averages out, and the drift of the circle over the ground is the wind. In straight flight it can only compare airspeed with groundspeed along the track, which refines the estimate slowly.
That works, and it is how gliding computers have done it for decades. But the result is at its best just after a thermal and grows older on every glide.
The hard part: where the nose points
To solve the triangle in straight flight you need the glider's heading. There are three ways to get it:
| Method | What it costs |
|---|---|
| A magnetic compass sensor | Calibration, and errors near steel parts, wiring and cockpit electronics |
| A second GNSS antenna | A second antenna installed far enough from the first, and a sensor box to read both |
| Heading from motion — Atmo | Nothing extra: gyros, accelerometers and GNSS that the Era already carries |
Atmo takes the third route. The gyros and accelerometers measure how the glider rotates and accelerates; GNSS measures how its velocity over the ground changes. Every turn, every speed change and every bump of turbulence shows up in both, and only the true heading makes the two agree. Atmo keeps checking that agreement — the motion sensors are read a hundred times a second, GNSS ten times — so the heading, and with it the wind, can be held without a compass. It works best while the glider turns and manoeuvres, and least well in long, perfectly smooth straight flight; the limits below say what that means in practice.
What runs inside
At the heart of Atmo is an estimator that tracks nineteen quantities together, a hundred times per second:
- the glider's attitude in three axes, heading included
- its position
- its velocity through the air in three axes — which also gives angle of attack and sideslip
- the slow drift of the gyros
- the wind in three axes
Each estimate carries its own uncertainty. Atmo only publishes what it can vouch for: until the estimate has settled after takeoff, or whenever the inputs stop making sense, the Wind page and the cyan smart-vario needle show no value rather than a guess.
The vertical wind needs the glider in the equation
The vertical component is the subtle one. The airflow does not meet the fuselage head-on: at thermalling speed the nose sits higher relative to the flight path, in fast cruise lower, and it changes again with load in a turn. Get that angle wrong by one degree at 110 km/h and the netto is wrong by about half a metre per second.
So Atmo models the glider as well as the air. From the dynamic pressure and the load the glider is pulling it works out how much lift the wing is making, and from that the angle at which the airflow meets the fuselage at every speed and in every turn. That is what separates the glider's own sink from the motion of the airmass — and why a horizontal gust, which changes the airspeed but not the air's vertical motion, is not meant to show up as lift.
Today that model is a built-in one — the polar and wing loading of a typical standard-class glider — not the polar, ballast and bugs you set in your Era. The vertical reading in straight flight is therefore approximate, and more so the further your glider is from that model. Once you are established in a thermal, the smart vario shows the climb measured by the instrument's total-energy vario, which the model does not affect.
When the glider is far from steady flight — a sharp pull-up, a stall, a high-g manoeuvre — the model no longer describes it either. Atmo is designed to recognise this: it pauses its vertical channel and holds the smart vario until the glider is flying steadily again. Stalls and hard pull-ups can still briefly produce a false reading. The horizontal wind keeps running throughout.
What Atmo learns while you fly
Several errors that would normally need a workshop calibration are measured in flight instead:
- Airspeed system error. An error in the pitot-static system is fixed to the glider, so it turns with the glider. Over a full circle it averages out of the wind, and what remains is the error itself. Atmo uses each thermalling circle to refine its airspeed correction, separately for slow, medium and fast speeds.
- Air density. True airspeed depends on air density, which is usually computed from the outside air temperature. A sun-heated temperature probe can make that several percent wrong. During any climb or descent of a few hundred metres Atmo compares static pressure with GNSS altitude and measures the density of the air directly.
- Gyro drift. The drift of the gyros is part of the estimator itself and is followed throughout the flight.
- Instrument tilt. Each time the Era is switched on, Atmo measures how the instrument is tilted — between switch-on and the first GPS fix, while the glider stands still for a few seconds. It takes the glider's attitude at that moment as its level reference, so a glider resting nose-high on its tail wheel gives it a slightly wrong one. Calibration, accuracy and troubleshooting explains why that matters and how to give it a better reference.
What you see in the cockpit
- Current wind — direction and speed, refreshed continuously in circling and in straight flight.
- Average wind — the wind of roughly the last minute and a half, steadier through gusts.
- Smart vario — one vario signal for needle, numbers and sound: built from the airmass in cruise and on thermal entry, and from the climb you actually achieve once you are established in a thermal.
- Attitude — with Atmo running, the Era's AHRS page shows Atmo's own attitude estimate, ahead of an LX AHRS module on the CAN bus (an iLevil or gMicro connected to the Era still comes first).
The first three are explained in flying with Atmo 3D. The wind and the smart vario are also shared over the CAN bus with a second-seat instrument and sent to flight apps — see Atmo 3D data: second seat, NMEA and your own software.
Honest limits
Measuring wind from motion is powerful, but it is not magic. Knowing the limits makes the numbers more useful, not less:
- Heading is weakest in smooth straight flight. Turns, speed changes and ordinary turbulence all sharpen it. On a long glide in smooth air there is little to observe, and the straight-flight wind can drift by several knots — more in perfectly smooth air — until the next turn re-anchors it. The average wind smooths this; it does not correct it. For a final glide, plan with the more pessimistic of Atmo's wind and the classic wind.
- The vertical reading uses a generic glider model. See above: the straight-flight smart vario is approximate for gliders that differ from a standard-class sailplane.
- No airspeed, no wind. Atmo needs airflow over the pitot. On the ground, during the takeoff roll and below roughly 30 km/h indicated it shows nothing — that is correct behaviour, not a fault.
- It needs the Era's own GPS receiver. The instrument's GPS antenna must be connected and see the sky. An Era that takes its position from a FLARM unit instead cannot run Atmo.
- It needs an honest installation. A working pitot-static system, the instrument fixed firmly in the panel and a sensible level reference.
- It is new. Atmo is refined with every firmware release, so keep your Era up to date.
Where to go next
- Activating Atmo 3D on your Era
- Flying with Atmo 3D: the Wind page, the smart vario and the sound
- Atmo 3D: calibration, accuracy and troubleshooting
- The theory behind the classic wind calculation: how your computer knows the wind in LX Academy.
- The product page: Atmo 3D wind.