<!-- canonical: https://docs.jmrp.io/phonometry/reference/api/aeroacoustics/anp-fleet/ -->
Source: https://docs.jmrp.io/phonometry/reference/api/aeroacoustics/anp-fleet/

EASA ANP fleet database bridge for the ECAC Doc 29 airport-noise chain.

The ECAC Doc 29 method in [`phonometry.aircraft.airport_noise`](/phonometry/reference/api/aeroacoustics/airport-noise/) places an
aircraft's noise at a receiver from a Noise-Power-Distance (NPD) table and a
flight profile. Both come, for real aircraft types, from the **Aircraft Noise
and Performance (ANP)** database maintained by EUROCONTROL/EASA: per aircraft it
tabulates NPD curves (`LAmax` and `SEL` versus slant distance for a set of
engine power settings, per operation mode) and default trajectories.

This module reads the ANP database tables (the semicolon-delimited CSV exports)
and exposes, for a given aircraft identifier and operation:

* [`AnpNpdCurves`](/phonometry/reference/api/aeroacoustics/anp-fleet/#anpnpdcurves) -- the NPD curves (`LAmax`/`SEL` versus distance for
  each tabulated power), with a `.plot()`;
* [`AnpProfile`](/phonometry/reference/api/aeroacoustics/anp-fleet/#anpprofile) -- the default fixed-point trajectory as a Doc 29 flight
  path `(N, 5)` with the takeoff/landing ground-roll masks, with a `.plot()`;
* [`AnpAircraft`](/phonometry/reference/api/aeroacoustics/anp-fleet/#anpaircraft) -- the aircraft metadata plus convenience wiring
  ([`AnpAircraft.event_level`](/phonometry/reference/api/aeroacoustics/anp-fleet/#anpaircraftevent_level), [`AnpAircraft.noise_contour`](/phonometry/reference/api/aeroacoustics/anp-fleet/#anpaircraftnoise_contour)) that feeds
  the NPD curves and the profile straight into the existing Doc 29 functions.

[`load_anp_database`](/phonometry/reference/api/aeroacoustics/anp-fleet/#load_anp_database) returns an [`AnpDatabase`](/phonometry/reference/api/aeroacoustics/anp-fleet/#anpdatabase). Called without a path
it loads the full EASA ANP database (archive version 2.3) shipped with the
package (see `aircraft/data/anp/PROVENANCE.md`); pointed at a directory it
reads any other ANP CSV export the user provides.

Aircraft whose default trajectory is published as *procedural steps* rather than
as fixed points are reached through [`phonometry.aircraft.flight_performance`](/phonometry/reference/api/aeroacoustics/flight-performance/),
the ECAC Doc 29 Vol. 2 Appendix B performance model:
[`AnpDatabase.flight_profile`](/phonometry/reference/api/aeroacoustics/anp-fleet/#anpdatabaseflight_profile) flies the published procedure for an
aerodrome and its weather, and [`AnpDatabase.procedural_profile`](/phonometry/reference/api/aeroacoustics/anp-fleet/#anpdatabaseprocedural_profile) returns the
result as the same Doc 29 flight path the fixed-point bridge produces, so either
kind of profile feeds the same chain. NPD curves are available for every aircraft
regardless.

Source (clean-room, implemented from the published table format): EASA ANP
database v2.3 (2020) and the ECAC Doc 29 4th ed. Vol 2 NPD/profile conventions.

> Auto-generated from the source docstrings by `scripts/generate_api_docs.py` (`make api-docs`). Do not edit by hand.

## AnpAircraft

```python
AnpAircraft(
    aircraft_id: str,
    description: str,
    engine_type: str,
    num_engines: int,
    weight_class: str,
    mounting: str,
    npd_id: str,
    power_parameter: str,
    approach_spectral_class_id: str,
    departure_spectral_class_id: str,
    _database: AnpDatabase,
)
```

One ANP aircraft type: metadata plus NPD/profile access and Doc 29 wiring.

**Attributes**

| Name | Description |
| :--- | :--- |
| `aircraft_id` | ANP aircraft identifier (e.g. `"747100"`). |
| `description` | Human-readable aircraft/engine description. |
| `engine_type` | `"Jet"`, `"Turboprop"` or `"Piston"`. |
| `num_engines` | Number of engines. |
| `weight_class` | ICAO wake weight class. |
| `mounting` | Doc 29 engine mounting (`"wing"`/`"fuselage"`/`"propeller"`). |
| `npd_id` | ANP noise identifier. |
| `power_parameter` | Name/unit of the NPD power parameter. |
| `approach_spectral_class_id` | Spectral class of the approach NPD. |
| `departure_spectral_class_id` | Spectral class of the departure NPD. |

### AnpAircraft.event_level()

```python
AnpAircraft.event_level(
    observer: NDArray[np.float64] | list[float],
    operation: str,
    *,
    aerodrome: Aerodrome | None = None,
    stage_length: int | str = 1,
    metric: EventMetric = 'exposure',
    temperature_c: float | None = None,
    atmospheric_pressure_kpa: float | None = None,
    relative_humidity_percent: float | None = None,
    absorption: str = 'arp5534',
) -> FlyoverResult
```

Single-event level at a receiver (see [`AnpDatabase.event_level`](/phonometry/reference/api/aeroacoustics/anp-fleet/#anpdatabaseevent_level)).

### AnpAircraft.noise_contour()

```python
AnpAircraft.noise_contour(
    operation: str,
    *,
    x: NDArray[np.float64] | list[float],
    y: NDArray[np.float64] | list[float],
    aerodrome: Aerodrome | None = None,
    stage_length: int | str = 1,
    metric: EventMetric = 'exposure',
    temperature_c: float | None = None,
    atmospheric_pressure_kpa: float | None = None,
    relative_humidity_percent: float | None = None,
    absorption: str = 'arp5534',
) -> NoiseContourResult
```

Single-event ground contour (see [`AnpDatabase.noise_contour`](/phonometry/reference/api/aeroacoustics/anp-fleet/#anpdatabasenoise_contour)).

### AnpAircraft.npd_curves()

```python
AnpAircraft.npd_curves(operation: str, metric: str = 'SEL') -> AnpNpdCurves
```

NPD curves for this aircraft (see [`AnpDatabase.npd_curves`](/phonometry/reference/api/aeroacoustics/anp-fleet/#anpdatabasenpd_curves)).

### AnpAircraft.profile()

```python
AnpAircraft.profile(
    operation: str,
    stage_length: int = 1,
    *,
    profile_id: str | None = None,
) -> AnpProfile
```

Fixed-point profile (see [`AnpDatabase.profile`](/phonometry/reference/api/aeroacoustics/anp-fleet/#anpdatabaseprofile)).

### AnpAircraft.revised_npd_curves()

```python
AnpAircraft.revised_npd_curves(
    operation: str,
    metric: str = 'SEL',
    *,
    temperature_c: float,
    relative_humidity_percent: float,
    atmospheric_pressure_kpa: float = 101.325,
    absorption: str = 'arp5534',
) -> RevisedNpdCurves
```

NPD curves for another atmosphere (see [`AnpDatabase.revised_npd_curves`](/phonometry/reference/api/aeroacoustics/anp-fleet/#anpdatabaserevised_npd_curves)).

### AnpAircraft.spectral_class()

```python
AnpAircraft.spectral_class(operation: str) -> SpectralClass
```

Spectral class of this aircraft's NPD for an operation.

**Parameters**

| Name | Description |
| :--- | :--- |
| `operation` | `"departure"`/`"D"` or `"arrival"`/`"A"`. |

**Returns:** The [`SpectralClass`](/phonometry/reference/api/aeroacoustics/anp-fleet/#spectralclass) the ANP database assigns.

**Raises**

| Exception | When |
| :--- | :--- |
| KeyError | if the database carries no such class. |

## AnpDatabase

```python
AnpDatabase(
    aircraft: Mapping[str, dict[str, str]],
    npd: Mapping[tuple[str, str, str], tuple[NDArray[np.float64], NDArray[np.float64]]],
    distances: NDArray[np.float64],
    profiles: Mapping[tuple[str, str, str, int], NDArray[np.float64]],
    performance: _PerformanceTables | None = None,
    spectral_classes: Mapping[str, SpectralClass] | None = None,
)
```

A parsed ANP database (aircraft metadata, NPD curves and default profiles).

Build one with [`load_anp_database`](/phonometry/reference/api/aeroacoustics/anp-fleet/#load_anp_database). NPD curves are available for every
aircraft; default profiles are available for aircraft that have a fixed-point
trajectory in the database, and procedural-step profiles for those whose
coefficient and step tables the export carries.

### AnpDatabase.aircraft()

```python
AnpDatabase.aircraft(aircraft_id: str) -> AnpAircraft
```

Return the [`AnpAircraft`](/phonometry/reference/api/aeroacoustics/anp-fleet/#anpaircraft) for an identifier.

**Raises**

| Exception | When |
| :--- | :--- |
| KeyError | If the identifier is not in the database. |

### AnpDatabase.aircraft_ids

*property*

Sorted list of aircraft identifiers in the database.

### AnpDatabase.event_level()

```python
AnpDatabase.event_level(
    aircraft_id: str,
    observer: NDArray[np.float64] | list[float],
    operation: str,
    *,
    aerodrome: Aerodrome | None = None,
    stage_length: int | str = 1,
    metric: EventMetric = 'exposure',
    temperature_c: float | None = None,
    atmospheric_pressure_kpa: float | None = None,
    relative_humidity_percent: float | None = None,
    absorption: str = 'arp5534',
) -> FlyoverResult
```

Doc 29 single-event level of an ANP aircraft at a receiver.

Feeds the aircraft's profile and NPD curves into
[`phonometry.aircraft.airport_noise.event_level`](/phonometry/reference/api/aeroacoustics/airport-noise/#event_level).

**Parameters**

| Name | Description |
| :--- | :--- |
| `aircraft_id` | ANP aircraft identifier. |
| `observer` | Receiver position `(x, y, z)`, in metres. |
| `operation` | `"departure"`/`"D"` or `"arrival"`/`"A"`. |
| `aerodrome` | Fly the published procedural steps at this field through the Appendix B performance model instead of reading the tabulated fixed-point trajectory. Most ANP types publish only steps, so for them this is not an alternative but the only way in. |
| `stage_length` | ANP stage length (default 1). |
| `metric` | `"exposure"` (SEL) or `"maximum"` (LAmax). |
| `temperature_c` | Air temperature at the field, in °C, for the atmospheric impedance adjustment. Left unset it follows *aerodrome*, or the standard atmosphere when there is none. |
| `atmospheric_pressure_kpa` | Air pressure at the field, in kPa, likewise. |
| `relative_humidity_percent` | Relative humidity at the field, in percent. Given, the SEL and LAmax NPD curves are recalculated for that humidity and the temperature and pressure above by ECAC Doc 29 Vol. 2 Appendix D, with the aircraft's spectral class for the operation; left unset they stay in the SAE AIR-1845 atmosphere the database is normalised to. |
| `absorption` | The Appendix D absorption route, `"arp5534"` (default) or `"arp866a"`; read only with a humidity. |

**Returns:** A [`FlyoverResult`](/phonometry/reference/api/aeroacoustics/airport-noise/#flyoverresult).

### AnpDatabase.flight_profile()

```python
AnpDatabase.flight_profile(
    aircraft_id: str,
    operation: str,
    *,
    aerodrome: Aerodrome,
    stage_length: int | str = 1,
    profile_id: str | None = None,
    weight_lb: float | None = None,
) -> FlightProfile
```

Fly an aircraft's published procedure into a Doc 29 flight profile.

The ECAC Doc 29 Vol. 2 Appendix B model applied to this aircraft's ANP
procedural steps: the profile depends on the aerodrome and its weather,
which is why one has to be given and why the answer is not a table entry.

**Parameters**

| Name | Description |
| :--- | :--- |
| `aircraft_id` | ANP aircraft identifier. |
| `operation` | `"departure"`/`"D"` or `"arrival"`/`"A"`. |
| `aerodrome` | The [`Aerodrome`](/phonometry/reference/api/aeroacoustics/flight-performance/#aerodrome) to fly from, carrying its elevation, temperature, pressure and headwind. |
| `stage_length` | ANP stage length (default 1), which selects the take-off weight of a departure. |
| `profile_id` | Optional ANP profile identifier. |
| `weight_lb` | Weight to fly at, lb. `None` (default) takes the ANP default weight for the stage length on a departure, and 90 % of the maximum landing weight on an arrival, as Doc 29 defines it. |

**Returns:** A [`FlightProfile`](/phonometry/reference/api/aeroacoustics/flight-performance/#flightprofile).

**Raises**

| Exception | When |
| :--- | :--- |
| KeyError | If the aircraft has no procedural-step profile or no default weight for the request. |

### AnpDatabase.noise_contour()

```python
AnpDatabase.noise_contour(
    aircraft_id: str,
    operation: str,
    *,
    x: NDArray[np.float64] | list[float],
    y: NDArray[np.float64] | list[float],
    aerodrome: Aerodrome | None = None,
    stage_length: int | str = 1,
    metric: EventMetric = 'exposure',
    temperature_c: float | None = None,
    atmospheric_pressure_kpa: float | None = None,
    relative_humidity_percent: float | None = None,
    absorption: str = 'arp5534',
) -> NoiseContourResult
```

Doc 29 single-event ground contour of an ANP aircraft.

Feeds the aircraft's profile and NPD curves into
[`phonometry.aircraft.airport_noise.noise_contour`](/phonometry/reference/api/aeroacoustics/airport-noise/#noise_contour).

**Parameters**

| Name | Description |
| :--- | :--- |
| `aircraft_id` | ANP aircraft identifier. |
| `operation` | `"departure"`/`"D"` or `"arrival"`/`"A"`. |
| `x` | Grid x coordinates (along-track), in metres. |
| `y` | Grid y coordinates (lateral), in metres. |
| `aerodrome` | Fly the published procedural steps at this field through the Appendix B performance model instead of reading the tabulated fixed-point trajectory. Most ANP types publish only steps, so for them this is not an alternative but the only way in. |
| `stage_length` | ANP stage length (default 1). |
| `metric` | `"exposure"` (SEL) or `"maximum"` (LAmax). |
| `temperature_c` | Air temperature at the field, in °C, for the atmospheric impedance adjustment. Left unset it follows *aerodrome*, or the standard atmosphere when there is none. |
| `atmospheric_pressure_kpa` | Air pressure at the field, in kPa, likewise. |
| `relative_humidity_percent` | Relative humidity at the field, in percent. Given, the SEL and LAmax NPD curves are recalculated for that humidity and the temperature and pressure above by ECAC Doc 29 Vol. 2 Appendix D, with the aircraft's spectral class for the operation; left unset they stay in the SAE AIR-1845 atmosphere the database is normalised to. |
| `absorption` | The Appendix D absorption route, `"arp5534"` (default) or `"arp866a"`; read only with a humidity. |

**Returns:** A [`NoiseContourResult`](/phonometry/reference/api/aeroacoustics/airport-noise/#noisecontourresult).

### AnpDatabase.npd_curves()

```python
AnpDatabase.npd_curves(
    aircraft_id: str,
    operation: str,
    metric: str = 'SEL',
) -> AnpNpdCurves
```

NPD curves for an aircraft, operation and noise metric.

**Parameters**

| Name | Description |
| :--- | :--- |
| `aircraft_id` | ANP aircraft identifier. |
| `operation` | `"departure"`/`"D"` or `"arrival"`/`"A"`. |
| `metric` | `"SEL"` (default) or `"LAmax"`. |

**Returns:** An [`AnpNpdCurves`](/phonometry/reference/api/aeroacoustics/anp-fleet/#anpnpdcurves).

**Raises**

| Exception | When |
| :--- | :--- |
| KeyError | If the aircraft has no NPD data for the request. |
| ValueError | If the metric or operation is unknown. |

### AnpDatabase.performance_aircraft()

```python
AnpDatabase.performance_aircraft(aircraft_id: str) -> PerformanceAircraft
```

The aeroplane's ECAC Doc 29 Vol. 2 Appendix B coefficient set.

Gathers the engine, aerodynamic and weight tables into the
[`PerformanceAircraft`](/phonometry/reference/api/aeroacoustics/flight-performance/#performanceaircraft) the
performance model takes. The engine count, the maximum sea-level static
thrust and the maximum landing weight come from the aircraft table; the
approach weight follows from the last of those as Doc 29 defines it.

**Parameters**

| Name | Description |
| :--- | :--- |
| `aircraft_id` | ANP aircraft identifier. |

**Returns:** A [`PerformanceAircraft`](/phonometry/reference/api/aeroacoustics/flight-performance/#performanceaircraft).

**Raises**

| Exception | When |
| :--- | :--- |
| KeyError | If the aircraft is not in the database. |
| ValueError | If the export carries no performance tables at all, which is the case for an NPD-only export. |

### AnpDatabase.procedural_profile()

```python
AnpDatabase.procedural_profile(
    aircraft_id: str,
    operation: str,
    *,
    aerodrome: Aerodrome,
    stage_length: int | str = 1,
    profile_id: str | None = None,
    weight_lb: float | None = None,
) -> AnpProfile
```

A flown procedure as the flight path the Doc 29 noise chain reads.

`flight_profile` converted into the same [`AnpProfile`](/phonometry/reference/api/aeroacoustics/anp-fleet/#anpprofile) the
fixed-point bridge returns, so an aircraft that publishes procedural
steps and one that publishes fixed points feed
[`event_level`](/phonometry/reference/api/aeroacoustics/airport-noise/#event_level) and [`noise_contour`](/phonometry/reference/api/aeroacoustics/airport-noise/#noise_contour) alike. The units change on
the way (Appendix B works in feet, knots and pounds; the noise chain in
metres and metres per second) and the power setting stays the corrected
net thrust per engine the NPD tables are indexed on.

Takes the same arguments as `flight_profile`.

**Returns:** An [`AnpProfile`](/phonometry/reference/api/aeroacoustics/anp-fleet/#anpprofile).

### AnpDatabase.procedural_steps()

```python
AnpDatabase.procedural_steps(
    aircraft_id: str,
    operation: str,
    stage_length: int | str = 1,
    *,
    profile_id: str | None = None,
) -> tuple[DepartureStep, ...] | tuple[ApproachStep, ...]
```

The published procedure for an aircraft, as procedural steps.

The rows of the ANP departure or approach procedural-step table, in step
order, as the types
[`flight_performance`](/phonometry/reference/api/aeroacoustics/flight-performance/) flies. Approach
procedures are not tabulated per stage length, so `stage_length` is
read only for a departure.

**Parameters**

| Name | Description |
| :--- | :--- |
| `aircraft_id` | ANP aircraft identifier. |
| `operation` | `"departure"`/`"D"` or `"arrival"`/`"A"`. |
| `stage_length` | ANP stage length (default 1), departures only. |
| `profile_id` | Optional ANP profile identifier; `None` (default) selects `"DEFAULT"` when present, or the single available one. |

**Returns:** The steps, in order.

**Raises**

| Exception | When |
| :--- | :--- |
| KeyError | If the aircraft has no procedural-step profile for the request, or `profile_id` is not among the available ones. |
| ValueError | If `profile_id` is `None` and several profiles exist with none of them named `"DEFAULT"`. |

### AnpDatabase.profile()

```python
AnpDatabase.profile(
    aircraft_id: str,
    operation: str,
    stage_length: int | str = 1,
    *,
    profile_id: str | None = None,
) -> AnpProfile
```

Fixed-point trajectory for an aircraft, operation and stage length.

Aircraft may ship several fixed-point profiles for the same operation
and stage length (e.g. weight variants). With `profile_id=None` the
`"DEFAULT"` profile is selected when present; otherwise the single
available profile is used, and an ambiguous request (several profiles,
none named `"DEFAULT"`) raises listing the identifiers.

**Parameters**

| Name | Description |
| :--- | :--- |
| `aircraft_id` | ANP aircraft identifier. |
| `operation` | `"departure"`/`"D"` or `"arrival"`/`"A"`. |
| `stage_length` | ANP stage length (default 1). |
| `profile_id` | Optional ANP profile identifier (e.g. `"DEFAULT"`, `"3000LB"`); `None` (default) selects as described above. |

**Returns:** An [`AnpProfile`](/phonometry/reference/api/aeroacoustics/anp-fleet/#anpprofile) (a Doc 29 flight path with ground-roll masks).

**Raises**

| Exception | When |
| :--- | :--- |
| KeyError | If the aircraft is unknown, has no fixed-point profile for the request, or `profile_id` is not among the available ones. |
| ValueError | If `profile_id` is `None` and several profiles exist with none of them named `"DEFAULT"`. |

### AnpDatabase.revised_npd_curves()

```python
AnpDatabase.revised_npd_curves(
    aircraft_id: str,
    operation: str,
    metric: str = 'SEL',
    *,
    temperature_c: float,
    relative_humidity_percent: float,
    atmospheric_pressure_kpa: float = 101.325,
    absorption: str = 'arp5534',
) -> RevisedNpdCurves
```

NPD curves recalculated for another atmosphere (Doc 29 Vol. 2 Appendix D).

The curves of `npd_curves` revised by the increment of the
aircraft's own spectral class for the operation, as
[`revise_npd_curves`](/phonometry/reference/api/aeroacoustics/npd-atmosphere/#revise_npd_curves) computes
it.

**Parameters**

| Name | Description |
| :--- | :--- |
| `aircraft_id` | ANP aircraft identifier. |
| `operation` | `"departure"`/`"D"` or `"arrival"`/`"A"`. |
| `metric` | `"SEL"` (default) or `"LAmax"`. |
| `temperature_c` | Air temperature, in degrees Celsius. |
| `relative_humidity_percent` | Relative humidity, in percent. |
| `atmospheric_pressure_kpa` | Air pressure, in kPa (default 101.325). |
| `absorption` | `"arp5534"` (default) or `"arp866a"`. |

**Returns:** A [`RevisedNpdCurves`](/phonometry/reference/api/aeroacoustics/npd-atmosphere/#revisednpdcurves).

**Raises**

| Exception | When |
| :--- | :--- |
| KeyError | if the aircraft, its NPD data or its spectral class is missing. |
| ValueError | for an unknown metric, operation or absorption route. |

### AnpDatabase.spectral_class()

```python
AnpDatabase.spectral_class(class_id: int | str) -> SpectralClass
```

One spectral class of the database (ECAC Doc 29 Vol. 2 G4.3).

**Parameters**

| Name | Description |
| :--- | :--- |
| `class_id` | Spectral class identifier, as a number or as the table writes it (`103` or `"103"`). |

**Returns:** A [`SpectralClass`](/phonometry/reference/api/aeroacoustics/anp-fleet/#spectralclass).

**Raises**

| Exception | When |
| :--- | :--- |
| KeyError | if the export carries no such class, or no spectral-class table at all. |

### AnpDatabase.spectral_class_ids

*property*

Sorted list of the spectral class identifiers in the database.

## AnpNpdCurves

```python
AnpNpdCurves(
    aircraft_id: str,
    npd_id: str,
    metric: str,
    operation: str,
    power_parameter: str,
    powers: NDArray[np.float64],
    distances: NDArray[np.float64],
    levels: NDArray[np.float64],
)
```

ANP Noise-Power-Distance curves for one aircraft, metric and operation.

**Attributes**

| Name | Description |
| :--- | :--- |
| `aircraft_id` | ANP aircraft identifier. |
| `npd_id` | ANP noise identifier (shared by aircraft with the same NPD set). |
| `metric` | `"SEL"` or `"LAmax"`. |
| `operation` | `"A"` (arrival) or `"D"` (departure). |
| `power_parameter` | Name/unit of the power setting (e.g. corrected net thrust). |
| `powers` | Tabulated engine power settings (1-D, strictly increasing). |
| `distances` | Tabulated slant distances, in metres (1-D, strictly increasing). |
| `levels` | Tabulated event levels, shape `(len(powers), len(distances))`, in dB. |

The `powers`, `distances` and `levels` arrays are read-only views shared
with the parent database; copy them before mutating.

### AnpNpdCurves.level()

```python
AnpNpdCurves.level(
    power: float,
    distance: NDArray[np.float64] | list[float] | float,
) -> NDArray[np.float64]
```

Interpolated NPD level `L(P, d)` (Doc 29 Eq. 4-3/4-4).

**Parameters**

| Name | Description |
| :--- | :--- |
| `power` | Query engine power setting. |
| `distance` | Query slant distance(s), in metres. |

**Returns:** The interpolated level per query distance, in dB.

### AnpNpdCurves.plot()

```python
AnpNpdCurves.plot(
    ax: Axes | None = None,
    *,
    language: str = 'en',
    **kwargs: Any,
) -> Axes
```

Plot the NPD curve at each tabulated power versus slant distance.

## AnpProfile

```python
AnpProfile(
    aircraft_id: str,
    operation: str,
    profile_id: str,
    stage_length: int | str,
    path: NDArray[np.float64],
    ground_roll: NDArray[np.bool_],
    landing_roll: NDArray[np.bool_],
)
```

Default fixed-point trajectory of an ANP aircraft as a Doc 29 flight path.

**Attributes**

| Name | Description |
| :--- | :--- |
| `aircraft_id` | ANP aircraft identifier. |
| `operation` | `"A"` (arrival) or `"D"` (departure). |
| `profile_id` | ANP profile label (usually `"DEFAULT"`). |
| `stage_length` | ANP stage length (trip-distance/weight bin). Usually one of the numbered bins, but the database's own column also carries `"M"` for a maximum-weight procedure, so the label is kept as it is read. |
| `path` | Flight-path points, shape `(N, 5)`: `x, y, z` (m, along-track, lateral, altitude), engine power setting and true airspeed (m/s). |
| `ground_roll` | Boolean mask (length `N-1`) of takeoff ground-roll segments. |
| `landing_roll` | Boolean mask (length `N-1`) of landing rollout segments. |

`path` is a read-only view shared with the parent database; copy it before
mutating.

### AnpProfile.plot()

```python
AnpProfile.plot(
    ax: Axes | None = None,
    *,
    language: str = 'en',
    **kwargs: Any,
) -> Axes
```

Plot the trajectory altitude versus along-track distance.

## load_anp_database

```python
load_anp_database(path: Path | str | None = None) -> AnpDatabase
```

Load an EASA ANP database (aircraft, NPD curves and default profiles).

**Parameters**

| Name | Description |
| :--- | :--- |
| `path` | Directory of an ANP CSV export (the `*Aircraft.csv`, `*NPD_data.csv`, `*fixed_point_profiles.csv` tables, plus the optional performance tables the procedural-step model reads: `*engine_coefficients.csv`, `*Aerodynamic_coefficients.csv`, `*weights.csv` and the two `*procedural_steps.csv`, and the `*Spectral_classes.csv` table ECAC Doc 29 Vol. 2 Appendix D reads to recalculate the NPD curves for another atmosphere). If `None` (default), loads the full EASA ANP database v2.3 shipped with the package (see `aircraft/data/anp/PROVENANCE.md`). |

**Returns:** An [`AnpDatabase`](/phonometry/reference/api/aeroacoustics/anp-fleet/#anpdatabase).

**Raises**

| Exception | When |
| :--- | :--- |
| FileNotFoundError | If a required table is missing. |

## SpectralClass

```python
SpectralClass(
    class_id: str,
    operation: str,
    description: str,
    frequencies_hz: NDArray[np.float64],
    levels_db: NDArray[np.float64],
)
```

One ANP spectral class: the reference spectrum of a group of aircraft.

ECAC Doc 29 Vol. 2 G4.3: the average unweighted spectrum at the time of the
maximum level, at 1 000 ft, normalised to the same SAE AIR-1845 attenuation
rates as the NPD data and, for historical reasons, to 70 dB in the 1 kHz
band. Every aircraft is assigned one for approach and one for departure.
Appendix D recalculates the aircraft's NPD curves for another atmosphere
from it ([`revise_npd_curves`](/phonometry/reference/api/aeroacoustics/npd-atmosphere/#revise_npd_curves)).

**Attributes**

| Name | Description |
| :--- | :--- |
| `class_id` | Spectral class identifier (`"103"`, `"205"`...). |
| `operation` | `"A"` (approach) or `"D"` (departure). |
| `description` | The aircraft family the class describes. |
| `frequencies_hz` | Nominal one-third-octave-band centre frequencies, in Hz, from 50 Hz to 10 kHz. |
| `levels_db` | Band levels at 1 000 ft, in dB. |

### SpectralClass.plot()

```python
SpectralClass.plot(
    ax: Axes | None = None,
    *,
    language: str = 'en',
    **kwargs: Any,
) -> Axes
```

Plot the band levels versus frequency.