Is a reservation with a public transport ticket necessary for the ascent ?

Yes, in the summer season it is necessary to reserve a time slot (so-called boarding pass) for the ascent in addition to the public transport ticket. You avoid waiting times and secure your ascent, also with the SBB app. Without a reservation, there may be waiting times and in exceptional cases transportation may not be possible. Public transport ticket: purchase directly via the public transport channel, e.g. SBB app. Reserve a time slot here.