We are landing. What do I need to do?
at-ter-RAN-do — the gerund. 'Atterrare' is to land. FA-re — stress on first syllable.
As the aircraft begins its final descent and you want to confirm what preparations are needed.
'Stiamo atterrando' uses 'stare' + gerund to express an ongoing action in the present — 'we are landing'. This is the same construction as 'sto mangiando' (I am eating). 'Cosa devo fare?' (what do I need to do?) is a practical preparation question.
Devo rimettere il sedile in posizione verticale?
Do I have to put the seat upright?
Yes — always required for landing
Posso tenere il telefono acceso?
Can I keep my phone on?
In airplane mode, yes. Fully off is no longer required on most EU flights
Dove metto il vassoio del cibo?
Where do I put the food tray?
Fold it up and lock it before landing
The final approach announcement in Italian is typically: 'Signore e signori, tra pochi minuti atterreremo all'aeroporto di... Si prega di rimettere i sedili in posizione verticale, riporre i tavolini e allacciare le cinture di sicurezza.' (Ladies and gentlemen, in a few minutes we will land at... airport. Please return seats to the upright position, stow tray tables and fasten seatbelts.)