Deco gases must be checked (✓) to be used by the algorithm. The richest checked gas within PPO₂ limits is selected at each depth.
O₂ CYLINDER
CCRClosed Circuit Setup
Diluent and setpoints for this plan
SP per segment can be set in each segment row. Cylinders below are bailout OC gas.
Dive profile
No segments added yet.
Enter cylinders and profile, then press Calculate
Deco plan CCR
Depth
GF ceiling
Avg. depth
Rock bottom & TTS
Ascent trigger
Start your ascent when either your dive computer shows TTS ≤ your target, or your gas reaches the rock bottom reserve — whichever comes first. Reduce the TTS below the plan maximum for extra conservancy.
min
Gas plan
Unused
Emergency
Normal
Cylinders
No.
Mix
Size (ℓ)
Usage (bar)
Limits
Mix
Depth (m)
Density (g/ℓ)
PPO₂
Notes on the gas plan: The gas plan calculates cylinder pressures based on real-world gas behavior.
Add cylinder
Add segment
Bottom time includes descent time to this section.
Dive configuration
Algorithm
Model
The type decompression model to use.
ZHL-16C-GF
Gradient factor
GF Low/High change the conservatism used by the decompression model.
30/85
Auto-set GF Low
Automatically sets GF Low to match the first gas switch depth (Andy Davis method). GF Hi − GF Lo is kept ≥ 10. Recalculates whenever gases or the plan change.
Environment
Salinity
Saltier water is heavier and increases pressure at depth.
Salt
Altitude
The altitude of the water surface at which the dive is taking place.
0 m
Diver & Gas
Ascent speed
The speed at which the diver is planning to ascent to stops or the surface.
10 m/min
Descent speed
The speed at which the diver is planning to descent to planned bottom sections.
2 m/min
Gas usage
Average gas consumption at 1 atm during normal diving. Also known as SAC or RMV rate.
20 l/min
Gas usage emergency
Average gas consumption at 1 atm during an emergency scenario. Also known as panic SAC or RMV rate.
30 l/min
Gas usage deco
Gas consumption during deco stops and ascents. Usually lower than normal SAC — the diver is stationary and relaxed.
10 l/min
Decompression
Deco stop interval
The interval at which to make deco stops.
3 m
Last deco stop
Depth at which the last deco stop will be made.
6 m
Max PPO₂
Maximum allowed PPO₂ during the dive (except for decompression).
1.4
Max deco PPO₂
Maximum allowed PPO₂ during decompression stops and ascents to decompression stops.
1.6
Gas switch time
Time in minutes to perform a gas switch at a switch depth. Diver breathes new gas during this pause.
1 min
Min stop time
Minimum hold time at each deco stop. 0 = hold only as long as the ceiling requires. 1 = traditional 1-min minimum per stop depth.
1 min
Switch deco gas at MOD
When enabled, switch to the richest available deco gas immediately upon reaching its MOD during ascent (optimal offgassing). When disabled, ascend on bottom gas and only switch when a required stop forces it.
CCR — O₂ & Hardware (in development)
CCR mode
Enable Closed Circuit Rebreather planning. The algorithm uses setpoint-based O₂ fraction instead of cylinder gas fractions. No deco gas switching occurs on CCR.
Total scrubber endurance (minutes). Depends on size and temperature.
180 min
Bailout switch time
Mandatory pause when switching to bailout gas (OC). Added to deco schedule.
2 min
Diluent, setpoints and O₂ cylinder are on the main planning page when CCR mode is active.
Multi-level
Use deco gas between sections
When ascending between multi-level sections, allow automatic use of deco gas.
Contingency plan
Deeper
How much deeper the contingency plan should be, added to the deepest section.
3 m
Longer
How much longer the contingency plan should be, added to the deepest section.
3 min
Defaults
Save as default settings
Save the current plan's settings as the starting configuration for all new plans.
Best mix for depth
Depth
metres
PPO₂
ata
Trimix
Include helium in the mix
Target EAD
narcotic depth (m)
Result
Best mix
O₂/He ratio
—
MOD
at 1.40 ata
—
N₂ fraction
balance gas
—
How it works: Best O₂% = PPO₂ ÷ absolute pressure at depth (10 m/bar). For trimix, helium replaces N₂ to match your target narcotic depth (EAD). Percentages are rounded to the nearest whole number.
MOD / END
O₂
percent (%)
He
percent (%)
Mix21/0O₂/He
Depth
metres
PPO₂ limit
for MOD calculation
Results
MOD
max operating depth
—
PPO₂ at depth
actual O₂ partial pressure
—
EAD
N₂ narcotic — He inert
—
END
N₂ + O₂ narcotic
—
EADD
N₂ narcotic — density based
—
Gas density
warn >5.2 ● limit >6.2 g/ℓ
—
EAD — equivalent air depth treating He as inert (N₂ narcosis only). END — narcotic depth counting both N₂ and O₂ as narcotic. EADD — density-equivalent depth; same breathing resistance as the mix on air at this depth.
Setting
Setting
Gradient factors
GF Low controls conservatism at the deepest stop. GF High controls conservatism at the surface. Lower = more conservative.
About
AeroPlus Deco
Innovation in aviation.
AeroPlus Deco is a technical dive decompression planner built on the Bühlmann ZHL-16C-GF algorithm — built by someone who lives and works at the intersection of two unforgiving disciplines.
TWO WORLDS, ONE DISCIPLINE
The name AeroPlus is no accident. Its author is a bush pilot and owner of African Flying Adventures, flying low and slow across remote African wilderness, and a developer of aviation software solutions — as well as a technical diver who plans dives well below recreational limits.
Aviation and technical diving share far more than most people realise. Both operate at the mercy of air pressure — pilots manage it as altitude above sea level, divers as depth below the surface. In both worlds, pressure is not abstract: it governs how your body absorbs gases, how your equipment performs, and whether you come home.
Both disciplines demand deep respect for the natural environment — weather, currents, visibility, terrain. In the African bush or 60 metres underwater, nature does not negotiate. Both require technical skill and situational awareness maintained through continuous training, because in the moment when things go wrong, muscle memory and procedure are all you have.
Above all, both are built on checklists, procedures and teamwork. A pre-dive gas check and a pre-flight checklist serve the same purpose: to create a systematic defence against human error when the stakes are life and death. Neither a pilot nor a technical diver improvises when it matters.
What this app does
✓ Bühlmann ZHL-16C with gradient factors (GF Lo/Hi)
✓ Multi-gas planning with automatic gas switching
✓ Trimix support (N₂ + He + O₂)
✓ CCR closed-circuit rebreather planning (in development)
✓ CNS% and OTU oxygen toxicity tracking
✓ Rock bottom gas reserves per cylinder
✓ Consecutive dive planning with tissue offgassing
✓ Contingency plans (deeper / longer)
✓ Gas density warnings (5.2 / 6.2 g/ℓ thresholds)
✓ Partial pressure gas blending calculator
✓ Auto GF Low matching first gas switch depth (Andy Davis method)
✓ Export dive plan as text or printable report
✓ Save & restore plans via JSON
Free & transparent. This app is free to use, share and modify. All calculations run entirely in your browser — no data is ever sent to any server.
AeroPlus Deco is open source and community-supported. Found a bug or have a feature idea? Open an issue on GitHub — it's the best way to track requests and contribute to the project.
⚠ Important disclaimer. Always double-check your decompression calculations using a certified dive planning tool or qualified dive professional. This app is provided for educational and planning assistance only and must not be used as your sole source of decompression data. Diving involves serious risks — incorrect decompression can result in injury or death.
About support
AeroPlus Deco is an unsupported app provided free of charge. There is no dedicated support team.
Tips, bug reports, or feature suggestions are welcome.
Save data
Copy this JSON and save it somewhere safe. On your own web server, the file downloads automatically instead.
Load data
Choose a saved .json file or paste JSON data below to restore your plans.
Export Dive Plan
Report
Details
AeroPlus Deco — About›
ZHL-16C-GF Algorithm
Gas Blending
Cylinder
Current fill
Target mix
Top-up gas
Gas analysis depth
Partial pressure blending method: He is added first, then pure O₂, then the top-up gas to reach the final pressure. Fill pressures shown are what your gauge should read after each step. Always fill in order: He → O₂ → top-up.