---
title: "Air breaks"
description: "Cycle decompression off high-ppO₂ gas at a set interval: what triggers the cycle, how long each phase runs, and which algorithms honour it."
---

> Documentation Index
> Fetch the complete documentation index at: https://docs.divelogic.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Air breaks

import { AirBreaksCard } from "@/components/react/PlannerSettingsScreens";

An air break interrupts decompression on a high-oxygen gas with a period on a
leaner one, to hold down central-nervous-system oxygen exposure over a long
stop. The **Air Breaks** card, in the Decompression section, schedules that
cycle for you.

## The fields

- **Air Breaks**: on or off. A new plan arrives with it off, and the rest of
  the controls appear only once it is enabled.
- **CNS Trigger**: a percentage between 0 and 100, starting at 80 %.
- **Runtime Trigger**: a number of minutes. The regime starts at whichever
  trigger is reached first, and a plan with neither set never triggers.
- **Deco Interval**: minutes on the primary deco gas before each break,
  starting at 20 and greater than zero.
- **Break Duration**: minutes each break runs, starting at 5, also greater than
  zero.
- **Break Gas**: every gas in the plan by name, plus an empty option. A new
  plan has none chosen.
- **Break Setpoint (bar)**: rebreather plans only, between 0.20 and 1.60. Set
  it and the break is taken by dropping the loop setpoint rather than switching
  off the loop, and the break gas is not used.

Once triggered, the diver alternates the deco interval and the break until the
decompression obligation clears. Break time is spent at the stop depth on a
leaner mix, so the stop grows to compensate.

## Which algorithms honour it

**Bühlmann ZHL-16C** and **Thalmann E-L** both schedule air breaks, and so does
**VPM-B**, because selecting VPM-B plans the dive on Bühlmann. **Hybrid OC**,
**DiveLogic Frontier** and **Thalmann GF Calibration** do not apply air breaks
at all; their controls stay visible and editable and change nothing.

> **Caution**
>
> No warning is emitted when an unsupported algorithm silently ignores the
> setting. If air breaks matter to the dive, plan it on Bühlmann or Thalmann and
> confirm the break segments appear in the schedule before you trust the runtime.

## Watch for

- **A break gas that is not in the plan disables the regime**, at **Warning**
  severity: *"Air-break gas index N is out of range (M gas(es) configured); air
  breaks disabled."*
- **A zero or negative interval or break duration disables it too**:
  *"Air-break interval and break durations must both be positive; air breaks
  disabled."* In both cases the schedule is computed without breaks.
- **Break segments appear as separate rows** at the stop depth, with the break
  gas named in the **Gas** column. Read them in the **Advanced** view, which
  puts ppO₂ next to the gas.

## Next

[Descent and ascent rates](/planning/rates) is next. Also worth reading:
[oxygen exposure](/theory/oxygen-exposure), for what CNS % counts.

Source: https://docs.divelogic.ai/planning/air-breaks/index.mdx