Air France · Small wind or brass

Yes

Cabin: yes

Under 115 cm in total and 12 kg it is your hand baggage item.

You can buy it a seat on this airline.

Air France rules

An instrument and case under 115 cm in total (height + length + width) may be your hand baggage item, up to 12 kg. You keep a small under-seat bag as well.
Over 115 cm and up to 45 kg, it must travel on an additional paid seat, booked at least 48 hours ahead with customer service approval.
The case must have rounded corners and should be a hard case.
In the hold, an instrument counts as a checked bag up to 158 cm in total and 23 kg in Economy. A hard case is required.
Light and Basic fares do not include a free checked bag.
Over 32 kg or 300 cm in total needs approval at least 48 hours ahead.

Before you leave for the airport

Measure the case and weigh it packed. Staff measure the case, never the instrument.
Check the fare. The cheapest fares often include only an under-seat bag.
Check who operates each leg. The operating airline's rule applies.
A seat for the instrument is booked by phone, often 48 hours or more ahead.
Photograph the instrument and case before you leave home.
Board as early as you can.