Suunto Nautic User Guide
Mandatory dive alarms
The following table shows all the mandatory warnings you may see during a dive. You can find the reason for the alarm and the solution of the issue in the table.
If multiple alarms occur simultaneously, the error with the highest priority will be displayed. Acknowledge the first alarm by pressing any button and the next one will appear.
| Alarm | Explanation | How to resolve the alarm? |
|---|---|---|
 | Ascent speed exceeds safe speed of 10 m (33 ft) per minute for five seconds or more. | Stay within the green ascent rate indicators. Monitor for symptoms of DCS. Use extra conservatism for future dives. |
 | Decompression ceiling broken by more than 0.6 m (2 ft) on a decompression dive. | Descend deeper than the displayed ceiling value. |
 | Partial pressure of oxygen exceeds the maximum level (>1.6). | Immediately ascend or change to a gas with lower oxygen percentage. |
 | Partial pressure of oxygen exceeds the set level for the gas. | Immediately ascend or change to a gas with lower oxygen percentage. |
 | Central Nervous System (CNS) Oxygen Toxicity level at 80% or 100% limit. | Switch to a gas with a lower ppO2 or ascend shallower (within decompression ceiling). |
 | 80% or 100% of recommended daily limit for OTU reached. | Switch to a gas with a lower ppO2 or ascend shallower (within decompression ceiling). |
  | Tank pressure is below 50 bar (725 psi). | Change gas to a higher tank pressure or ascend to safety stop depth and terminate dive. |
 | Not inside the safety stop window. | Stay within the safety stop window 3 m – 6 m. |
 | NDL is less than 5 minutes. | Ascend shallower to avoid mandatory decompression stops. |
 | The decompression ceiling is broken for more than 3 min and your decompression stop is missed. | Descend to the ceiling depth indicated in the switch window. |