Learn French: Nous sommes sur le point de descendre, à moins d'un problème. - We are about to go down, unless there is a problem.

The phrase à moins de is followed directly by a noun or infinitive, acting like the English phrase 'short of' or 'barring'. It does not need a verb like il y a to make sense in French. If you wanted to explicitly include the verb, you would have to change the structure completely and use the subjunctive: à moins qu'il n'y ait un problème.

Why use à moins d'un problème here instead of sauf un problème?

While sauf and à moins de can both convey exceptions, à moins de is specifically used for conditions that could alter a planned outcome (like a problem stopping you from going down). Sauf is generally used to exclude an item from a group, such as saying 'everyone except him' (tout le monde sauf lui).

Could I say Nous allons descendre instead of Nous sommes sur le point de descendre?

You could, but it removes the urgency. Nous allons descendre simply uses the near future to state 'We are going to go down'. The expression être sur le point de followed by an infinitive is a great B2 structure that means 'to be about to' or 'to be on the verge of', making the action feel much more immediate.

Does descendre only mean physically going down stairs, or could this be about something else?