# Glide Ratio API
> Aircraft glide-performance maths as an API, computed locally and deterministically — the glide-distance, glide-ratio and reachability numbers a pilot, flight-instructor or flight-sim developer works an engine-out or soaring problem with. The glide-distance endpoint gives the still-air distance you can cover = height above the ground × the glide ratio (L/D): from 5,000 ft at a 9:1 ratio you reach about 45,000 ft, ~7.4 nm, with the answer in feet, nautical miles and kilometres. The glide-ratio endpoint reads the slope straight off the polar — glide ratio = forward speed ÷ sink rate (1 knot ≈ 101.27 ft/min), so 60 kt at a 600 ft/min sink is about 10:1, a 5.6° glide path — and gliders reach 40–60:1, a light single ~9:1, an airliner ~17:1. The reach endpoint answers the practical question: the height needed to reach a field = distance ÷ glide ratio, the arrival height is what is left, and it only counts as making it if that clears a safety reserve (default 1,000 ft) for the circuit and approach. Everything is computed locally and deterministically, so it is instant and private. Ideal for flight-planning and EFB apps, gliding and soaring tools, flight-simulator and training utilities, and aviation-safety calculators. Pure local computation — no key, no third-party service, instant. Still-air estimates — adjust for wind, configuration and a margin. 3 compute endpoints. For density altitude use a density-altitude API; for runway wind components a crosswind API.

## Authentication
All requests require your oanor API key in the `x-oanor-key` header. Get one at https://www.oanor.com/developer/keys.

```bash
curl -H "x-oanor-key: oanor_live_…" "https://api.oanor.com/glideratio-api/..."
```

## Pricing
- **Free** (Free) — 6,100 calls/Mo, 2 req/s
- **Starter** ($11/Mo) — 63,000 calls/Mo, 6 req/s
- **Pro** ($33/Mo) — 265,000 calls/Mo, 15 req/s
- **Mega** ($101/Mo) — 1,350,000 calls/Mo, 40 req/s

## Endpoints

### Glide

#### `GET /v1/glide-distance` — Glide distance from height and ratio

**Parameters:**
- `height_ft` (query, required, string) — Height above landing point (ft) Example: `5000`
- `glide_ratio` (query, required, string) — Glide ratio (L/D) Example: `9`

**Example:**
```bash
curl -H "x-oanor-key: $KEY" \
  "https://api.oanor.com/glideratio-api/v1/glide-distance?height_ft=5000&glide_ratio=9"
```

**Response:**
```json
{
    "data": {
        "note": "Still-air glide distance = height above the ground × the glide ratio (L/D): from 5,000 ft at a 9:1 ratio you can reach about 45,000 ft, ~7.4 nm. A headwind shortens it and a tailwind extends it, since the airframe still sinks at the same rate while the ground moves underneath — so plan an engine-out glide with a margin, and remember the figure is for the best-glide speed; faster or slower both steepen the descent.",
        "inputs": {
            "height_ft": 5000,
            "glide_ratio": 9
        },
        "glide_distance_ft": 45000,
        "glide_distance_km": 13.72,
        "glide_distance_nm": 7.41
    },
    "meta": {
        "timestamp": "2026-06-07T08:18:05.642Z",
        "request_id": "cd6e46cf-b57c-45d3-89dc-4d62c9591d86"
    },
    "status": "ok",
    "message": "Glide distance",
    "success": true
}
```

#### `GET /v1/glide-ratio` — Glide ratio from airspeed and sink

**Parameters:**
- `airspeed_kt` (query, required, string) — Airspeed (knots) Example: `60`
- `sink_rate_fpm` (query, required, string) — Sink rate (ft/min) Example: `600`

**Example:**
```bash
curl -H "x-oanor-key: $KEY" \
  "https://api.oanor.com/glideratio-api/v1/glide-ratio?airspeed_kt=60&sink_rate_fpm=600"
```

**Response:**
```json
{
    "data": {
        "note": "Glide ratio = forward speed ÷ sink rate (in the same units): 60 kt (≈ 6,076 ft/min) at a 600 ft/min sink is about 10:1, a 5.7° glide path. It is the slope of the glide, read straight off the aircraft's polar — gliders reach 40–60:1, a light single ~9:1, an airliner ~17:1. The best ratio comes at one particular speed; fly faster or slower and the sink rate rises, steepening the glide.",
        "inputs": {
            "airspeed_kt": 60,
            "sink_rate_fpm": 600
        },
        "glide_ratio": 10.13,
        "glide_angle_deg": 5.64,
        "glide_ratio_label": "10.1:1"
    },
    "meta": {
        "timestamp": "2026-06-07T08:18:05.735Z",
        "request_id": "d68692a3-cf26-4676-a06d-2a0ef28a8aef"
    },
    "status": "ok",
    "message": "Glide ratio",
    "success": true
}
```

#### `GET /v1/reach` — Airfield reachability

**Parameters:**
- `height_ft` (query, required, string) — Current height (ft) Example: `5000`
- `glide_ratio` (query, required, string) — Glide ratio (L/D) Example: `9`
- `distance_nm` (query, required, string) — Distance to field (nm) Example: `5`
- `safety_height_ft` (query, optional, string) — Safety reserve (ft, default 1000) Example: `1000`

**Example:**
```bash
curl -H "x-oanor-key: $KEY" \
  "https://api.oanor.com/glideratio-api/v1/reach?height_ft=5000&glide_ratio=9&distance_nm=5&safety_height_ft=1000"
```

**Response:**
```json
{
    "data": {
        "note": "Height needed to reach a field = distance ÷ glide ratio; the arrival height is what is left over. It only 'makes it' here if that arrival height clears a safety reserve (default 1,000 ft) for the circuit and approach — gliding to exactly zero leaves nothing for manoeuvring. Subtract wind, and never bet on the book ratio: a rough field or a draggy configuration eats into it fast.",
        "inputs": {
            "height_ft": 5000,
            "distance_nm": 5,
            "glide_ratio": 9,
            "safety_height_ft": 1000
        },
        "makes_it": true,
        "height_needed_ft": 3376,
        "arrival_height_ft": 1624
    },
    "meta": {
        "timestamp": "2026-06-07T08:18:05.827Z",
        "request_id": "70eb0860-7def-4e83-8bfd-f93cd064c438"
    },
    "status": "ok",
    "message": "Reachability",
    "success": true
}
```

### Meta

#### `GET /v1/meta` — Spec

**Example:**
```bash
curl -H "x-oanor-key: $KEY" \
  "https://api.oanor.com/glideratio-api/v1/meta"
```

**Response:**
```json
{
    "data": {
        "notes": "ft, nm, km, kt, fpm. distance = height × ratio; ratio = airspeed ÷ sink (1 kt = 101.27 ft/min); height needed = distance ÷ ratio. Still-air estimates — adjust for wind and configuration. For density altitude use a density-altitude API; for wind components a crosswind API.",
        "service": "glideratio-api",
        "endpoints": {
            "GET /v1/meta": "This document.",
            "GET /v1/reach": "Whether a field is within glide range, and the arrival height.",
            "GET /v1/glide-ratio": "Glide ratio (L/D) and glide angle from airspeed and sink rate.",
            "GET /v1/glide-distance": "Still-air glide distance from height and glide ratio."
        },
        "description": "Glide-performance maths: glide distance from height and ratio, glide ratio from airspeed and sink, and airfield reachability."
    },
    "meta": {
        "timestamp": "2026-06-07T08:18:05.920Z",
        "request_id": "9b43b575-a3cb-44fb-8a1a-f92ee1e78d6a"
    },
    "status": "ok",
    "message": "Meta",
    "success": true
}
```


---
Marketplace page: https://www.oanor.com/api/glideratio-api
OpenAPI spec: https://www.oanor.com/api/glideratio-api/openapi.json