If true altitude is the height above sea level, what is altitude simulation? Altitude simulation is duplicating the physiological effects of true altitude. Those effects are caused by the partial pressure of oxygen – the product of oxygen concentration and atmospheric pressure. Altitude simulation requires modifying oxygen levels according to barometric pressure.

Altitude is not an oxygen percentage. A given oxygen level at low pressure yields a different altitude than it does at higher pressure. Regulating oxygen levels without regard to atmospheric pressure cannot simulate altitude accurately.

Calculating simulated altitude requires four steps:

  1. Measure barometric pressure – an essential step in calculating the partial pressure of oxygen is measuring barometric pressure. Barometric pressure is continually changing. Calculations of the partial pressure of oxygen without barometric readings must rely on assumed pressures and cannot yield accurate altitude simulation.
  1. Accurately measure oxygen concentration. Because oxygen readings are so critical, ACT uses two state-of-the-art sensors made specifically for altitude simulation, then validates their readings by cross-referencing one sensor to another. There is no more accurate way to measure oxygen.
  1. Calculate the partial pressure of oxygen using actual barometric pressure and oxygen percentage.
  1. Convert the partial pressure of oxygen to a simulated altitude – this requires empirically validated algorithms. ACT uses the West Equations, which are based on the most recent science.

ACT’s is the only system that executes these steps and provides true altitude simulation. Paying attention to these scientific fundamentals is critical to simulating altitude.


Other systems:

  • Use a single oxygen sensor – with no way to know if it is accurate and with no validation of oxygen readings against other sensors.
  • Have no pressure sensor – they assume a barometric pressure
  • Do not calculate the partial pressure of oxygen.
  • Use outdated atmospheric tables

Systems that ignore scientific fundamentals and do not calculate the partial pressure of oxygen are not scientific instruments and can only crudely approximate altitude.