> For the complete documentation index, see [llms.txt](https://docs-integration.squake.earth/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs-integration.squake.earth/api-calculations-request-response/travel/flight/flight-defra.md).

# Flight: DEFRA 🇬🇧

:bulb: **High-Level Description:**

The Department for Environment, Food, and Rural Affairs (DEFRA) of the United Kingdom plays a key role in shaping environmental policies and approaches to carbon reduction. As part of its sustainability initiatives, DEFRA has developed a carbon calculation methodology specifically for the flight passenger sector, providing a standardized and credible means to evaluate the emissions associated with air travel.

DEFRA's methodology for evaluating carbon emissions from passenger flights incorporates a range of factors. These include the aircraft's fuel consumption, flight distance, type of aircraft, and even the indirect effects of high-altitude emissions. The aim is to offer a holistic view of a flight's environmental impact. By developing this standardized approach, DEFRA not only aids the aviation industry in understanding and reducing its carbon footprint but also provides a reliable reference point for policymakers and environmental advocacy groups.

**Versioning:** Add `methodology_version` to pin a specific **Conversion Factors** year (e.g., `"2024"`). If omitted, SQUAKE **uses the latest supported year**.

***

### **Sample API Requests**

#### A. Without audit mode (for pre-booking/quotes)

```json
{
  "expand": ["items"],
  "items": [
    {
      "audit": false,
      "type": "flight",
      "methodology": "DEFRA",
      "external_reference": "test_4",
      "number_of_travelers": 2,
      "origin": "LON",
      "destination": "LAX",
      "booking_class": "first",
      "aircraft_type": "737",
      "radiative_forcing_index": true,
      "energy_scope": "wtw",
      "methodology_version": "2024"
    }
  ]
}
```

#### B. With audit mode (for finalized/post-booking calculations)

```json
{
  "expand": ["items"],
  "audit_for": "<Auditable Entity ID>",
  "items": [
    {
      "audit": true,
      "type": "flight",
      "methodology": "DEFRA",
      "external_reference": "test_4",
      "number_of_travelers": 2,
      "origin": "LON",
      "destination": "LAX",
      "booking_class": "first",
      "aircraft_type": "737",
      "radiative_forcing_index": true,
      "energy_scope": "wtw",
      "methodology_version": "2024"
    }
  ]
}
```

> **Note:** `audit_for` is optional. Provide when calculating on behalf of a specific Auditable entity; otherwise omit.

* **Default Values**
  * `"booking_class": "average"`
  * `"energy_scope": "wtw"`
  * `"radiative_forcing_index": true`
  * `"methodology_version"`: **latest supported DEFRA year (default if omitted)**
* **Calculation Specifics**
  * An **8% uplift** is applied to Great Circle Distance (GCD) to account for indirect paths, delays, etc.
  * If both `distance_in_km` and `origin`/`destination` are provided, **`distance_in_km` takes precedence**.

***

### **API Request Items**

* `"type": "flight"` **(required)**
* `"methodology": "DEFRA"` **(required)**
* `"methodology_version"`: DEFRA **Conversion Factors** year (e.g., `"2024"`). **Optional**; if omitted → **latest supported year**.
* `"external_reference"`: Unique identifier (max 128 chars).
* `"number_of_travelers"`: Minimum `1` (**default:** `1`).
* `"origin"`: For airports use IATA/ICAO code (format: `^[A-Z]{3,4}$`, e.g. `"MUC"`), for other locations used in trade and transportation use UN/LOCODE codes (format: `^[A-Z]{2}\W?[A-Z2-9]{3}$`, e.g. `"DEHAM"`). You can also pass lat/long (format: `^[-+]?\d{1,3}\.\d{1,10}\s?,\s?[-+]?\d{1,3}\.\d{1,10}$`, e.g. `"+40.712,-74.006"`).
* `"destination"`: For airports use IATA/ICAO code (format: `^[A-Z]{3,4}$`, e.g. `"MUC"`), for other locations used in trade and transportation use UN/LOCODE codes (format: `^[A-Z]{2}\W?[A-Z2-9]{3}$`, e.g. `"DEHAM"`). You can also pass lat/long (format: `^[-+]?\d{1,3}\.\d{1,10}\s?,\s?[-+]?\d{1,3}\.\d{1,10}$`, e.g. `"+40.712,-74.006"`).
* Multi-leg itineraries: use **`routing`** (hyphen-separated airports) instead of `origin`/`destination` — see [**Flight: Routing (multi-leg)**](/api-calculations-request-response/travel/flight/flight-routing.md).
* `"distance_in_km"`: If present, **overrides** origin/destination resolution (not used as the routed total when **`routing`** is set; see Flight: Routing).
* `"booking_class"`: If not provided, pass `fare_class` + `airline` to auto-resolve; **default:** `"average"`.
* `"aircraft_type"`: IATA/ICAO code; **only applied when at least one airport is in the UK**.
* `"fare_class"` / `"airline"`: Mutually exclusive with `"booking_class"`.
* `"radiative_forcing_index"`: Apply high-altitude climate impact multiplier (**default:** `true`).
* `"sustainable_fuels"`: Indicates SAF use (reduces emissions in SQUAKE; not part of official DEFRA factors).
* `"carbon_reduction_percentage_of_total"`: Fraction `0–1` from SAF; **default:** `0`.
* `"energy_scope"`: `"wtw"` (**default**) or `"ttw"`.
* `"audit"`: boolean (optional). Set to `true` to create immutable audit records for finalized calculations. Must be enabled for your account.

***

### **Aircraft Type Distribution**

| Domestic | Short-Haul | Long-Haul |
| -------- | ---------- | --------- |
| 32N      | 32N        | 32N       |
| 32Q      | 32Q        | 32Q       |
| 319      | 318        | 320       |
| 320      | 319        | 321       |
| 321      | 320        | 332       |
| AT4      | 321        | 333       |
| AT5      | 332        | 339       |
| AT7      | 333        | 343       |
| 738      | 359        | 359       |
| D38      | AT7        | 338       |
| ER3      | 7M8        | 7M8       |
| ER4      | 7M9        | 738       |
| E70      | 733        | 752       |
| E90      | 734        | 763       |
| E95      | 735        | 764       |
| J41      | 736        | 772       |
| SF3      | 737        | 773       |
|          | 738        | 77F       |
|          | 739        | 77W       |
|          | 752        | 788       |
|          | 753        | 789       |
|          | 763        | 781       |
|          | 772        |           |
|          | 77W        |           |
|          | 788        |           |
|          | 789        |           |
|          | 221        |           |
|          | 223        |           |
|          | CR9        |           |
|          | DH8        |           |
|          | E70        |           |

***

### **Sample API Response**

```json
{
  "carbon_quantity": 15273823,
  "carbon_unit": "gram",
  "items": [
    {
      "carbon_quantity": 15273823,
      "carbon_unit": "gram",
      "external_reference": "test_4",
      "type": "flight",
      "methodology": "DEFRA",
      "methodology_version": "2024",
      "distance": 8804.0,
      "distance_unit": "kilometer"
    }
  ]
}
```

***

### **Versions**

* **Behavior:** If `methodology_version` is omitted, SQUAKE automatically applies the **latest supported** DEFRA Conversion Factors year. Pin a year for reproducibility and audit readiness.

***

### **Bibliography**

* UK Government — **Greenhouse gas emissions: Research & statistics**: <https://www.gov.uk/environment/greenhouse-gas-emissions#research\\_and\\_statistics>
* Bramwell, R., et al. (2024). *Government Greenhouse Gas Conversion Factors for Company Reporting — Methodology*. (Methodology paper PDF).