# Tutorial: Building a Cargo Bay Picker

# Tutorial: Building a Cargo Bay Picker

Learn how to use the Fleet Operations API to show shippers which cargo bays have room, before they book a container.

> **Tip:**
> Cargo bays open for booking 14 days before launch, at 08:00 station time.

---

## 1. Checking Availability

Before showing bay options to your users, fetch the bays that can hold their cargo's temperature class:

<Tabs>
  <TabItem label="Request">
```http
GET /v2/cargo/bays?temperature=cryo HTTP/1.1
Host: fleet.cosmocargo.dev
X-API-Key: YOUR_API_KEY
```
  </TabItem>
  <TabItem label="Response">
```json
[
  {
    "id": "8f14e45f-ceea-4e67-a1b2-3c4d5e6f7a8b",
    "vesselId": "1c9e2a7b-4d3f-4b8a-9e6d-2f1a0b3c4d5e",
    "capacityTons": 5000,
    "usedTons": 3200,
    "temperature": "cryo"
  }
]
```
  </TabItem>
</Tabs>

Free capacity is `capacityTons - usedTons`: 1,800 tons in this bay.

---

## 2. Temperature Classes

| Temperature | Description | Best For |
| :--- | :--- | :--- |
| **Ambient** | Pressurized hold kept at 18–24 °C. | General freight and electronics |
| **Cryo** | Held below −150 °C for the whole voyage. | Vaccines, cryo-sleep pods, cultured cells |
| **Plasma-shielded** | Wrapped in a plasma field against radiation storms. | Reactive minerals and sensitive instruments |

---

## 3. Booking the Container

Once the shipper picks a bay, book the container with `POST /containers/book` (Cargo Container Specifications API). The booking confirmation and launch reminders go to the notification channels in the request.