Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Line | Terminals | Status | Length | Total number of stations | Operator |
| --- | --- | --- | --- | --- | --- |
| Line 1 | Etxebarri / Plentzia | Complete | 31km | 29.0 | Metro Bilbao S.A. |
| Line 2 | Basauri / Kabiezes | Complete | 20km | 25.0 | Metro Bilbao S.A. |
| Mamariga Shuttle | Santurtzi / Mamariga | Complete | 500 m | 2.0 | Metro Bilbao S.A. |
| Line 3 | Etxebarri-Norte / Matiko | Under construction | 5.885km | 7.0 | Metro Bilbao S.A. |
| Airport Line | Matiko / Aireportua | Under construction | 6.491km | 3.0 | EuskoTren |
| Line 4 | Matiko / Rekalde | In studies | 6km | 7.0 | Metro Bilbao S.A. |
| Line 5 | Etxebarri / Usansolo | In studies | 8,8km | 6.0 | Metro Bilbao S.A. |
Question:
What is the status of the airport line?
Answer:
Under construction