Hover Performance Calculator (IGE / OGE)
Estimate the maximum gross weight at which a given helicopter can hover in ground effect (IGE) and out of ground effect (OGE) at the current density altitude. Modeled on POH performance charts for Robinson R22, R44, and Bell 206. Inability to hover OGE is one of the most common factors cited in high-density-altitude rotorcraft accidents.
Calculator inputs and results
Aircraft
Atmospheric conditions
Source: linear approximation of POH hover ceiling charts (Section 5 in Robinson POHs, Performance Section in Bell 206). Real POH curves are non-linear; this calculator gives a ballpark only. Always verify with the actual POH performance chart for the specific aircraft, including correction for wind. Inability to hover OGE is one of the most common NTSB-cited factors in high-density-altitude rotorcraft accidents.
How this calculator works
Density altitude is computed from field elevation, altimeter setting, and OAT using the FAA-H-8083-25B formula (PA = elevation + (29.92 - altimeter) × 1000, DA = PA + 120 × (OAT - ISA at PA)).
Maximum hover weight is approximated as a linear reduction from the sea-level standard value, with separate slopes for IGE (in ground effect, typically within one rotor diameter of the surface) and OGE (out of ground effect). Slopes vary by aircraft and are derived from POH performance curves.
Power margin: the calculator compares current gross weight against the computed maximum hover weight at the current density altitude, expressed as percentage of maximum and as available margin in pounds. Negative margin means the aircraft cannot hover at that weight in those conditions.
Compliance basis: 14 CFR 91.103 requires the pilot in command to be familiar with all available performance information before flight. Hover capability is a core element of takeoff planning for confined area and pinnacle operations.
Default assumptions & sources
Every default value the calculator starts with, the realistic range you'd see in the field, and the source we used to set it.
| Input | Default | Typical range | Source |
|---|---|---|---|
| R22 max IGE hover weight | 1,370 lb @ SL standard | POH Section 5 | Robinson R22 POH hover ceiling chart |
| R44 max OGE hover weight | 2,500 lb @ SL standard | POH Section 5 | Robinson R44 POH hover ceiling chart |
| Bell 206 IGE/OGE slope | 75/130 lb per 1000 ft DA | POH Performance | Bell 206 Performance Section |
| Density altitude formula | FAA-H-8083-25B PHAK | Standard | Pilot's Handbook of Aeronautical Knowledge |
What's not modeled
The calculator covers the major cost and time line items. These additional factors apply in some cases but aren't included in the estimate:
- Wind benefit during hover - 5+ kt wind significantly improves OGE hover capability
- Engine condition, mixture, oil temperature - all affect actual power available
- Engine type variants - turbocharged, supercharged, and FADEC turbines have different DA sensitivities
- Anti-ice / heater bleed-air penalty for turbine helicopters
- Aircraft modifications - external loads, sensors, antennas all reduce hover ceiling
- Non-linear POH curves - the actual chart is curved, this is a straight-line approximation
Frequently asked questions
What is the difference between hover IGE and hover OGE?
IGE (in ground effect) is hovering within approximately one rotor-diameter of the surface, where ground effect reduces induced drag and reduces power required. OGE (out of ground effect) is hovering at altitude where ground effect is negligible - power required is higher. A helicopter that can hover IGE at sea level may not be able to hover OGE at 5,000 ft DA. OGE capability is what matters for confined area operations, pinnacle landings, external load, and most HEMS scenarios.
#Why is OGE hover capability a common NTSB accident factor?
Many helicopter accidents at high density altitude involve pilots who could hover IGE at the landing site but lost effective lift attempting an OGE departure - especially during confined area takeoff. NTSB safety studies of mountain and high-DA accidents cite this scenario repeatedly. Always verify OGE capability for the planned takeoff profile, not just the hover IGE check at the surface.
#How does this calculator handle non-standard atmosphere?
The density altitude formula (FAA-H-8083-25B) automatically accounts for non-standard pressure (via altimeter setting) and non-standard temperature (via OAT). A hot day at a high-elevation airport produces a density altitude well above the field elevation - the calculator handles this directly. Humidity is not modeled - on a humid day actual hover capability is slightly less than computed.
#What about wind during hover?
Wind during hover is NOT modeled by this calculator but it has a major effect. A 5-knot headwind component during hover effectively converts the operation into a low-airspeed forward flight, providing translational lift and reducing power required. OGE hover capability improves significantly with even moderate wind. POH performance charts often publish a separate 'wind benefit' curve.
#Why are the slopes different between aircraft types?
Hover power required is a function of disk loading (rotor thrust per square foot of disc area). Higher disk loading aircraft (Bell 206, turbine medium helicopters) lose hover capability faster with density altitude than lower disk loading aircraft (Robinson R22). The numbers in the calculator reflect this - Bell 206 IGE/OGE slope is approximately 75/130 lb per 1000 ft DA, while R22 is approximately 50/85.
#Related guides & tools
This calculator provides estimates only. Actual aircraft performance and regulatory compliance vary by specific aircraft serial number, density altitude, gross weight, equipment installations, and operator's FAA-approved General Operations Manual / OpSpec. Always verify with primary sources: the FAA (faa.gov), 14 CFR (eCFR at ecfr.gov), your aircraft Rotorcraft Flight Manual (RFM) or Pilot Operating Handbook (POH), the relevant FAA Advisory Circular, and NTSB safety studies for the operational profile.