The larger airlines seem to agree on how to accommodate musical instruments. Most allow you to walk aboard with a smaller case at no extra charge.
But it’s always best to be armed with the knowledge of your airline’s policies and here they are!
Southwest
Airlines
Carry-On Dimensions: 10 x 16 x 24 inches
Personal Item Dimensions: 8.5 x 13.5 x 18.5 inches
If your musical instrument (including case or covering) exceeds carry-on restrictions, it CAN be carried onboard.
The instrument must fit in an overhead bin or under a seat onboard the aircraft.
Space in overheard compartments is NOT guaranteed. Seats may be bought for larger instruments that do not fit in the overhead compartment at a price “no greater than the Child’s Fare.”
Southwest assumes no liability for any damage sustained to the item during transport.
American
Airlines
Carry-On Dimensions: 9 x 14 x 22 inches
Personal Item Dimensions: 8 x 14 x 18 inches
You can travel with small musical instruments as your carry-on item on a first come, first serve basis as long as it fits in the overhead bin or fits under the seat in front of you.
Seats may be bought for larger instruments that do not fit in the overhead compartment at an “applicable adult fare.”
American Airlines will only be liable for damages to musical instruments if your instrument is in a hard-sided case and the outside of the case is visibly damaged.
Delta
Carry-On Dimensions: 9 x 14 x 22 inches
Personal Item Dimensions: Personal items must be able to fit securely under the seat in front of the passenger.
Guitars and other smaller musical instruments, such as violins, will be accepted as your free carry-on baggage item on Delta and Delta Connection® carrier’s flights. These items must easily fit in the overhead bin or other approved storage location in the cabin.
Based on available space at the time of boarding, space is NOT guaranteed.
Musical instruments may be gate claimed at the discretion of the passenger and as a result of limited overhead space.
No information on liability, but assume they don’t take responsibility.
United
Airlines
Carry-On Dimensions: 9 x 14 x 22 inches
Personal Item Dimensions: 9 x 10 x 17 inches
Many tickets allow one free carry-on item, but with Basic Economy tickets you are only allowed one personal item and must pay for all carry-on or checked baggage.
You can carry a small musical instrument on board if it’s in a hard case. These instruments will count as a carry-on bag if placed in the overhead bin. If placed in the seat in front of you, they’ll count as a personal item.
You may buy a seat for a musical instrument that’s too fragile or bulky to handle as a checked bag.
For travel within the U.S., United Airlines is not liable for the loss of, damage to or delay in delivery of high-value items. For most international travel, their liability for destruction, loss, delay or damage to checked and carry-on bags is limited.
If you’re traveling with a string instrument, please loosen the strings to protect the instrument against damage caused by expansion and contraction. This can happen because of temperature changes during the flight.
JetBlue
Carry-On Dimensions: 9 x 14 x 22 inches
Personal Item Dimensions: 8 x 13 x 17 inches
A musical instrument is allowed in place of one carry-on item. “Basic Blue” fares do NOT include a free carry-on item. To carry on your instrument for free, purchase a Blue or higher fare ticket.
The standard carry-on baggage size limitations do NOT apply to musical instruments. The overhead bins can easily accommodate items up to 22″ x 14″ x 9″. Longer items, such as a guitar or tenor sax, may still fit in a bin with partial dividers. The aircraft do not have closets to stow musical instruments.
JetBlue is NOT required to give musical instruments priority over other carry-on baggage.
Damage to musical instruments will only be covered if the item is checked inside a hard-sided case designed to protect its contents, and only if permitted items are in the case. Any item checked inside a soft-sided container will be accepted, but not covered by liability.
Items exceeding 99 pounds will not be accepted as checked bags. You may be able to purchase a seat for large musical instruments that weigh up to 165 pounds.
Save $5 by adding checked bags to your ticket more than 24 hours before your flight.
Spirit
Airlines
Carry-On Dimensions: 10 x 18 x 22 inches
Personal Item Dimensions: 8 x 14 x 18 inches
You need to pay for anything other than a small personal item, whether you are carrying them on or checking them. It is cheapest to pay for your baggage at time of purchase, and most expensive at the gate.
Musical instruments are permitted as carry-on baggage as long as they fit within Spirit Airlines carry-on dimensions.
Spirit Airlines may ask you to sign a limited liability release to release them from liability for loss/damage of the instrument.
The maximum size for luggage is 100 pounds or 80 linear inches, but larger musical instruments may qualify as “special items” and be allowed with prior permission from Spirit Airlines. If the instrument exceeds the size restrictions for carry-on baggage and/or the customer believes that the instrument is too fragile to be handled as checked baggage, the customer may purchase an extra seat for the instrument at applicable fare.