# Aviation Calculators – ISA Atmosphere

> Aviation Calculators – ISA Atmosphere is a paid API for AI agents from aviation-calc.x402tookit.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-29).

Returns International Standard Atmosphere properties at a given pressure altitude: temperature, pressure, density, speed of sound, and optional ISA deviation from actual OAT.

## Facts

- Endpoint: GET https://aviation-calc.x402tookit.com/isa-atmosphere?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/aviation-calculators-isa-atmosphere-8366f7b0
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_RfmIOw0XaA68Ug2dus-7n

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability aviation-calculators-isa-atmosphere-8366f7b0
```

Example prompt: What are the standard ISA atmosphere values at 35000 feet pressure altitude — temperature, pressure, density, and speed of sound — and if the actual OAT is -45°C, what's the ISA deviation?

## When to prefer this

Use this endpoint when you need precise International Standard Atmosphere values at a specific pressure altitude for aviation performance calculations, flight planning, Mach number derivation, or ISA deviation analysis. Prefer this over general weather APIs when you need theoretical standard atmosphere properties (not actual measured conditions) or when computing ISA deviation by comparing standard to observed temperature.

## Known failure modes

- Altitude out of range (-1500 to 65000 ft) returns an error or null results
- Missing required altitudeFt parameter causes a validation error
- oatC omitted means ISA deviation fields return null — not an error but incomplete output
- Non-numeric inputs for altitude or temperature cause schema validation failure

## How this service works

Standard atmosphere at an altitude: temperature, pressure, density, sound speed, and ISA deviation for a measured temperature.

## Output

Returns a JSON object with ISA temperature in °C and °F, pressure in hPa and inHg, air density in kg/m³, density ratio, speed of sound in knots, the atmospheric layer name, and — if an actual OAT was provided — the ISA deviation in °C and rule-of-thumb ISA temperature. Also includes the queried altitude and source metadata.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "altitudeFt"
     ],
     "properties": {
      "oatC": {
       "type": "number",
       "description": "Actual outside air temperature in C, to get the ISA deviation"
      },
      "altitudeFt": {
       "type": "number",
       "description": "Pressure altitude in feet, -1500 to 65000"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "asOf": {
       "type": [
        "null",
        "string"
       ]
      },
      "oatC": {
       "type": [
        "null",
        "number"
       ]
      },
      "layer": {
       "type": [
        "null",
        "string"
       ]
      },
      "source": {
       "type": [
        "null",
        "string"
       ]
      },
      "reasons": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      },
      "summary": {
       "type": [
        "null",
        "string"
       ]
      },
      "verdict": {
       "type": [
        "null",
        "string"
       ]
      },
      "degraded": {
       "type": [
        "boolean",
        "null"
       ]
      },
      "altitudeFt": {
       "type": [
        "null",
        "number"
       ]
      },
      "disclaimer": {
       "type": [
        "null",
        "string"
       ]
      },
      "notChecked": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      },
      "densityRatio": {
       "type": [
        "null",
        "number"
       ]
      },
      "isaDeviationC": {
       "type": [
        "null",
        "number"
       ]
      },
      "isaDensityKgM3": {
       "type": [
        "null",
        "number"
       ]
      },
      "isaPressureHpa": {
       "type": [
        "null",
        "number"
       ]
      },
      "speedOfSoundKt": {
       "type": [
        "null",
        "number
… (truncated)
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/aviation-calculators-isa-atmosphere-8366f7b0/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from aviation-calc.x402tookit.com](https://www.zero.xyz/host/aviation-calc.x402tookit.com/llms.txt)