Compute Out-of-Ground-Effect (OGE) hover ceilings, water bucket payload limits, terrain downdraft sink rates, and NWCG GAR risk envelopes for high-elevation wildland operations.
Aircraft gross weight exceeds OGE hover power capacity at this density altitude. Drop site requires jettison or reduced bucket dip.
| Component | Specification / Description | Weight (lbs) |
|---|
Superheated convection columns and high summer ambient temperatures drastically reduce air density. A 6,000-foot ridge at 100°F experiences a Density Altitude exceeding 9,500 feet, starving rotor blades of lift and gas turbine engines of oxygen and shaft horsepower.
Dip-site hovering over mountain lakes or portable dip tanks requires Out-of-Ground-Effect (HOGE) power. If water bucket weight is taken on beyond the HOGE gross weight curve, settling with power (Vortex Ring State) or insufficient collective reserve triggers catastrophic sink rates.
The Green-Amber-Red model synthesizes pilot fatigue, complex box canyon terrain, thermal downdrafts, and radio blind spots. Scores above 35 demand operational mitigation (lightening load, flying ridge contour paths); scores above 45 enforce immediate mission stand-down.
This explainer covers saved calculator arithmetic, not validated aircraft performance or flight planning. Pressure altitude is field elevation plus twenty nine point nine two minus altimeter setting times one thousand. For an illustrative five thousand foot field and twenty eight point nine two setting, it gives six thousand feet. Bars use point zero five pixels per foot: two hundred fifty and three hundred. The source then computes standard temperature as fifteen minus one point nine eight times pressure altitude in thousands. At six thousand this is three point one two Celsius. Density altitude adds one hundred eighteen point eight times outside temperature minus that standard, then rounds. Aircraft constants and this simplified model have not been checked against approved flight manuals. Holding pressure altitude fixed, the density-altitude expression changes by one hundred eighteen point eight feet per Celsius degree before rounding. For illustrative outside-temperature differences of five and ten Celsius above the source standard, added altitude is five hundred ninety four and eleven hundred eighty eight feet. Bars use point two five pixels per foot of added altitude, widths one hundred forty eight point five and two hundred ninety seven. This is sensitivity of the saved equation, not a validated operating limit. Temperature input uses a falsy fallback: a numeric zero Fahrenheit falls back to fifty nine Fahrenheit. That edge differs from a straightforward temperature conversion and must be preserved or repaired only within authorized scope. This video does not establish flightworthiness. The source uses eight point three four pounds per water gallon. Illustrative one hundred and two hundred gallons add eight hundred thirty four and sixteen hundred sixty eight pounds. Bars use point two pixels per pound, widths one hundred sixty six point eight and three hundred thirty three point six. Gross mass sums aircraft empty weight, crew, fuel and water, then rounds. The displayed maximum-water label derives a nonnegative difference between an authored hover-weight proxy and operating weight, divided by eight point three four and floored. For illustrative one thousand pounds of such margin, floor of one thousand divided by eight point three four gives one hundred nineteen gallons. Despite safe wording in the interface, this calculation has not been validated as a safe load or operational clearance. Actual aircraft limits and missions cannot be inferred from this explainer.