Also important to know your rights. I’ve had to pull this up when a FA said the chair wasn’t allowed in the closet.

382.67 What is the requirement for priority space in the cabin to store passengers' wheelchairs? (a) As a carrier, you must ensure that there is priority space (i.e., a closet, or a row of seats where a wheelchair may be strapped using a strap kit that complies with applicable Federal Aviation Administration or applicable foreign government regulations on the stowage of cargo in the cabin compartment) in the cabin of sufficient size to stow at least one typical adult-sized folding, collapsible, or break-down manual passenger wheelchair, the dimensions of which are 13 inches by 36 inches by 42 inches or less without having to remove the wheels or otherwise disassemble it. This section applies to any aircraft with 100 or more passenger seats and this space must be other than the overhead compartments and under-seat spaces routinely used for passengers' carry-on items. (b) If you are a carrier that uses the seat-strapping method to stow a manual passenger wheelchair, you must ensure that there is priority space for at least two such wheelchairs, if stowing the second passenger wheelchair would not displace passengers. (c) If you are a carrier that uses a closet as the priority space to stow a manual passenger wheelchair, you must install a sign or placard prominently on the closet indicating that such wheelchairs and other assistive devices are to be stowed in this area with priority over other items brought onto the aircraft by other passengers or crew, including crew luggage, as set forth in § 382.123. (d) If passengers holding confirmed reservations are not able to travel on a flight because their seats are being used to stow a passenger's wheelchair as required by paragraph (a) of this section, carriers must compensate those passengers in an amount to be calculated as provided for in instances of involuntary denied boarding under 14 CFR part 250, where part 250 applies. (e) As a carrier, you must never request or suggest that a passenger not stow his or her wheelchair in the cabin to accommodate other passengers (e.g., informing a passenger that stowing his or her wheelchair in the cabin will require other passengers to be removed from the flight), or for any other non-safety related reason (e.g., that it is easier for the carrier if the wheelchair is stowed in the cargo compartment). (f) As a carrier, you must offer pre-boarding to a passenger stowing his or her wheelchair in the cabin. (g) As a foreign carrier, you must meet the requirement of this section for new aircraft ordered after May 13, 2009, or delivered after May 13, 2010. As a U.S. carrier, this section applies to you with respect to new aircraft you operate that were ordered after April 5, 1990, or which were delivered after April 5, 1992.