Warnings and errors

Every message DiveLogic can raise on a plan or a gas, grouped by what you were doing when it appeared, with what caused it and what to do about it.

Every message DiveLogic can raise, grouped by what you were doing when it appeared. An advisory means the plan is computed and usable and there is something to look at; an error means the plan is unsafe as configured, or could not be computed all the way through, though a schedule is still shown in almost every case.

All of them arrive in the Dive Warnings list on the Review step: red rows are errors, amber rows advisories, and a row carrying a minute is pinned to that point in the dive.

The Dive Warnings list on a 60 m dive planned on air

Dive Warnings

ppO₂ 1.48 bar exceeds bottom limit 1.4 bar at 60m (level 1) (t=3 min)

Gas density 9.1 g/L exceeds NEDU limit of 6.2 g/L on gas air (t=28 min)

Gas switch to 100% at 21m: ppO₂ 3.12 > 1.6 (t=37 min)

CNS 107% exceeds 100% limit

Messages are quoted below as the app writes them. Figures shown in italics are filled in with your own dive’s numbers.

While choosing a gas

From the gas analysis behind every gas card, which judges the mix at the depth you are analysing it for. See Depth limits.

What the app says	What caused it	What to do
Error: `High gas density — exceeds 6.2 g/L`	The mix is denser than 6.2 g/L at that depth.	Add helium or dive shallower. This is the accepted upper limit, not an advisory.
Advisory: `Elevated gas density — exceeds 5.2 g/L`	Density is above 5.2 g/L but not yet above 6.2.	Work of breathing is climbing. Add helium if you have it.
Advisory: `High EAD — exceeds 30m`	The mix narcoses like air deeper than 30 m.	A narcosis advisory. The remedy is helium.
Error: `ppO₂ too high — exceeds 1.6 at depth`	Oxygen partial pressure at that depth is above 1.6 bar.	Change the mix or the depth. Nothing is breathable there as configured.
Advisory: `ppO₂ exceeds target 1.4`	ppO₂ is above the limit you set for this mix, but still under 1.6 bar.	Either accept it deliberately or raise the mix’s own limit knowingly.
Error: `MOD (33m) is shallower than dive depth`	The mix’s maximum operating depth does not reach the depth being analysed.	That cylinder cannot be breathed there.

A mix with no oxygen in it has no maximum operating depth, and never raises the last of those. The gas blender raises no messages of its own; a blend is impossible in exactly one situation, when the cylinder is already at or above the pressure you asked for. See Blending a mix.

While setting descent and ascent rates

What the app says	What caused it	What to do
Advisory: `Descent rate 25 m/min exceeds recommended 20 m/min`	A descent segment is faster than 20 m/min.	Slow it, or accept it deliberately.
Advisory: `Ascent rate 12 m/min (max depth → first stop) exceeds recommended 10 m/min`	The ascent from the bottom to the first stop is faster than 10 m/min.	The same.
Advisory: `Between-stop ascent rate 9 m/min exceeds recommended 6 m/min`	Movement between stops is faster than 6 m/min.	The same.
Advisory: `Final ascent rate 5 m/min (last stop → surface) exceeds recommended 3 m/min`	The last stop to the surface is faster than 3 m/min.	The same.

These are the planner’s recommended maxima, not model limits. The schedule is computed at whatever rate you set. See Descent and ascent rates.

While the plan is being computed

What the app says	What caused it	What to do
Error: `No gas mixes configured. Please add at least one gas mix.`	The plan has no gases. Nothing is computed.	Add a bottom gas.
Advisory: `Transit from 30m to 18m required mandatory decompression stops`	Moving between two of your levels went into decompression before reaching the shallower one.	Expected on a multi-level dive; worth knowing if you did not intend it.
Advisory: `ppO₂ 1.52 bar exceeds bottom limit 1.4 bar at 45m (level 1)`	Oxygen partial pressure at a level depth is above the working limit of 1.4 bar. Levels are counted from 1.	Change the mix, the switch depth, or the level’s depth.
Error: `ppO₂ 1.68 bar exceeds absolute limit 1.6 bar`	ppO₂ at a level depth is above 1.6 bar. Raised alongside the advisory above.	The same, and not optional.
Error: `Gas switch to 50% at 24m: ppO₂ 1.71 > 1.6`	Switching to that gas on the way up would put ppO₂ above 1.6 bar at the switch depth.	Move the switch shallower, or use a leaner mix.
Error: `Gas density 6.8 g/L exceeds NEDU limit of 6.2 g/L on gas 21/35`	The gas in use is denser than 6.2 g/L at that point in the dive.	Add helium.
Advisory: `Gas density 5.6 g/L exceeds SPUMS advisory of 5.2 g/L on gas 21/35`	Density above 5.2 g/L but not above 6.2.	The same, less urgently.
Error: `Decompression does not clear at 6 m with the configured gradient factors and available gas: the surfacing ceiling never drops below the stop. Ascent schedule truncated — increase GF_high or add a higher-O₂ decompression gas.`	The dive as configured has no way out: the ceiling never rises above the stop, so the schedule is cut off there.	Raise GF High, or carry a richer decompression gas. The schedule shown is incomplete.

See Warnings on a plan for working through a list of these.

While setting up air breaks

Both of these switch air breaks off and compute the schedule without them, rather than refusing the plan.

What the app says	What caused it	What to do
Advisory: `Air-break gas index 3 is out of range (2 gas(es) configured); air breaks disabled.`	The break gas you chose is no longer in the plan.	Pick the break gas again.
Advisory: `Air-break interval and break durations must both be positive; air breaks disabled.`	One of the two durations is zero.	Set both above zero. See Air breaks.

Oxygen exposure, at the end of the dive

Raised once for the whole dive. Within each pair only one appears, because the error replaces the advisory.

What the app says	What caused it	What to do
Error: `CNS 112% exceeds 100% limit`	The CNS clock for the dive is over 100 %.	Shorten the exposure, or lower the ppO₂ driving it: a lower setpoint, a leaner decompression gas, or air breaks.
Advisory: `CNS 86% exceeds 80% advisory`	CNS is over 80 % but under 100 %.	The same, with more room.
Error: `OTU 340 exceeds 300 single-dive limit`	Whole-body oxygen exposure is over 300 for the dive.	The same remedies. OTU matters most across repeated days.
Advisory: `OTU 240 exceeds 200 advisory`	OTU is over 200 but under 300.	The same.

See Oxygen exposure.

Counterdiffusion at a gas switch

Every counterdiffusion finding is raised as an error, and the schedule is computed either way: these checks never change your stops. They all read the same way, naming which switch, where, and what about it:

ICD: gas switch 21/35 → 50% at 21m — the detail

The switch is called a bailout switch instead when it is the move from the loop onto open circuit. The detail is one of six.

The detail	What caused it
`N₂ fraction increase 34.0% exceeds limit 20.0%`	Nitrogen fraction jumps by more than the limit across the switch.
`He fraction decrease 35.0% exceeds limit 15.0%`	Helium fraction drops by more than the limit.
`ppN₂ increase 0.83 bar exceeds limit 0.50 bar`	Nitrogen partial pressure jumps by more than the limit at the switch depth.
`ppHe decrease 1.05 bar exceeds limit 0.50 bar`	Helium partial pressure drops by more than the limit at the switch depth.
`switch at deco ceiling 9.0m`	The switch is made at or above the current decompression ceiling.
`EAD mismatch: from 18.4m to 24.6m (diff 6.2m)`	The two gases narcose very differently, more than the tolerance apart.

One switch can raise several at once; they are checked independently. Move the switch deeper or shallower, insert an intermediate mix so the helium step is smaller, or accept the switch knowingly. Every check and its limit can be adjusted; see ICD safety.

On a rebreather

These need CCR mode. The scrubber messages additionally need a scrubber duration; without one, no scrubber check runs.

What the app says	What caused it	What to do
Advisory: `Scrubber duration 0 min is not positive; scrubber tracking disabled`	The scrubber duration entered is zero or negative. No further scrubber check runs.	Enter the rated duration, or leave the field empty to turn tracking off deliberately.
Advisory: `Scrubber within 60 min of its 180 min rated duration`	The dive runs to within an hour of the rated duration.	Know where you are in the scrubber’s life.
Advisory: `Scrubber within 30 min of its 180 min rated duration`	Within half an hour. Raised alongside the 60-minute one.	The same, closer.
Error: `Scrubber rated duration 180 min exceeded by 25 min at surfacing`	The dive overruns the rated duration.	Repack, or plan a shorter dive.

Scrubber tracking never changes a stop of the schedule. A setpoint entered outside 0.4 to 1.6 bar is quietly pulled back to the nearest of those bounds rather than warned about. See Scrubber tracking.

While planning bailout

What the app says	What caused it	What to do
Error, with nothing computed: `Bailout planning supports the Bühlmann and Thalmann algorithms`	The plan is set to a hybrid model or GF calibration.	Switch the plan to Bühlmann or Thalmann to plan bailout.
Advisory: `VPM-B is not yet implemented; bailout scenarios use Bühlmann ZHL-16C`	The plan is set to VPM-B.	Nothing to fix, but know which model the scenarios came from.
Advisory: `3 bailout scenario(s) omitted — runtime beyond 5× the loop plan (210 min) is treated as not survivable`	Those gas combinations would take more than five times the loop plan’s runtime to surface, so they are dropped.	The omission is the finding: that subset cannot get you out from there.
Advisory: `More than 5 open-circuit-capable gases — combination scenarios omitted (planned: all gases and each individual gas)`	Six or more gases are usable off the loop, so only the full set and each single gas are planned.	Nothing to fix. The intermediate combinations are not shown.
Advisory: `Bailout gas not breathable below 30m — this scenario stays on the loop from 45m until 30m`	The shallowest usable bailout gas in that scenario cannot be breathed at the bail depth.	This is not a true bailout for the deepest part of the dive. Carry a gas breathable on the bottom.

See Bailout planning.

When a model cannot run

DiveLogic falls back to Bühlmann ZHL-16C and says so rather than refusing to give you a schedule.

What the app says	What caused it
Advisory: `VPM-B is not yet implemented — results shown are Bühlmann ZHL-16C. Please update your algorithm selection.`	VPM-B was selected. The advisory appears at the top of the list.
Advisory: `Hybrid OC: reason. Bühlmann ZHL-16C fallback used.`	The max-ceiling hybrid could not run, most often because the plan has no gases.
Advisory: `Hybrid Frontier: reason. Bühlmann ZHL-16C fallback used.`	The frontier hybrid could not run, for the same kind of reason.
Advisory: `Hybrid OC frontier solver found no feasible schedule. Bühlmann ZHL-16C fallback used.`	The frontier search produced nothing usable.
Advisory: `Hybrid OC: maximum model disagreement 8.4m — consider a more conservative schedule.`	The two models running inside the hybrid disagreed about the ceiling by more than 6 m at some point.

See Algorithms.