On the same united policy page it states that musical instruments can be personal items:
https://www.united.com/ual/en/us/fly/tr ... ry-on.html
You can carry a violin, guitar or other 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 are picking and choosing what you want to read and ignore in that link. The overriding caveat in all of this it must be safe, and it must not impede an evacuation, or become a projectile in an emergency.
From that link
"Personal item Your personal item should fit underneath the seat in front of you. The maximum dimensions for your personal item are 9 inches x 10 inches x 17 inches (22 centimeters x 25 centimeters x 43 centimeters)."
Some musical instruments can fit these dimensions.
"United Express flights
Our regional partner airlines use smaller aircraft. That means our United Express flights generally have less room in the overhead bins for carry-on bags. In some cases, roller bags and other larger carry-on items won't fit. In the chart below, you can check for the specific policies based on the operator of your next United Express flight.
Carrier - CommutAir
Carry-on bag policy = No carry-on carrier
What that means for you - Passengers are allowed to bring only (1) one personal item into the cabin. Any carry-on bag in addition to the (1) one personal item will be collected by the gate ramp agent planeside, green-tagged and placed in the cargo compartment.
If an item is too fragile or bulky to travel as a checked bag, you can buy a ticket for it. You can then carry the item on board and place it in a seat. See our cabin-seat baggage page for more information.
A violin can be worth 10 million dollars. If this rule would not be in place there would be absolutely no possibility for orchestras to travel in any way because putting 10 million dollar item into cargo hold is clearly out of the question as is sending it with UPS or FEDEX.
They simply buy a ticket for the instrument and it is secured into the seat next to them.
An expensive instrument also carries a huge liability for the airline compared with a bag full of dirty socks. So yeah, if I'm running an airline I too would want to be nice to someone flying with a violin. It's just good business.
There is no liability at all, from the "Contract of Carriage"
3. EXCLUSIONS: UA shall not be liable for the loss of, damage to or delay in delivery of any of the following:
u. Musical instruments-Guitars, violins, violas, cellos, organs, harps, drums;
As for the no-carry-on airline thing. Do people really think that a German violinist who bought a ticket on UA to fly FRA-IAD-TYS and back, was ever informed at any point in the transaction that one of her legs would be flown on a "no-carry-on" airline? I would think that she might have chosen a different route or travel option if that was the case.
Yes the operator and flight number is given the passenger. This passenger was a frequent flyer, they had the FAR on hand. This tells me it was not their first encounter with this. They are trying to avoid paying for the additional seat they would have been told about numerous times before.
Again from the "Contract of Carriage"
"Carry-on Free Baggage Allowance - UA will accept one piece of Carry-on Baggage free of charge, which, for purposes of this Rule, is referred to as the “Carry-on Free Baggage Allowance”, and one personal item such as a shoulder bag, backpack, briefcase, laptop bag or similar item, except, however, UA will not accept any Carry-on Baggage for passengers traveling on a Basic Economy fare and Basic Economy passengers whose baggage is checked at the gate will be charged the applicable checked bag service charge, plus a 25 USD/25 CAD gate handling service charge. Carry-on Baggage must not exceed the Maximum Outside Linear Dimensions of 9 inches (22 cm) x 14 inches (35 cm) x 22 inches (56 cm), which includes its wheels and handles. Personal items must not exceed 9 inches (22 cm) x 10 inches (25 cm) x 17 inches (43 cm), which includes any wheels and handles. A personal item that exceeds these maximum linear dimensions but is not greater than 9 inches (22 cm) x 14 inches (35 cm) x 22 inches (56 cm) will be considered as Carry-on Baggage. Carry-on Baggage or personal items suspected of being oversized may require being placed into a sizing unit to determine acceptability. Carry-on Baggage that exceeds the Maximum Linear Dimensions allowed or that exceeds the Carry-on Free Baggage Allowance will be considered as Checked Baggage and is subject to Checked Baggage service charges. For flights departing Yap, Federated States of Micronesia (YAP), the maximum weight of carry-on baggage is 25 lbs/11.3 kg; any bag heavier than this amount will be considered as Checked Baggage and is subject to Checked Baggage service charges, such as Excess and Oversize/Overweight Baggage charges. Carry-on Baggage may be stored in carry-on compartments of the aircraft if so equipped, or it must be retained in the Passenger’s custody and stored under a seat or in an overhead compartment approved for the carriage of such Baggage. See Rule 23 F) 5) below for UA’s Carry-on policy regarding musical instruments. Carry-on Baggage is subject to the following additional conditions:
Operations, space constraints, security directives and/or other safety considerations may require limitations to the allowable Carry-on Baggage on a specific flight.
UA reserves the right in its sole and absolute discretion to determine the suitability and place of storage of any items to be carried in the cabin of the aircraft.
UA reserves the right to check a Passenger’s Carry-on Baggage for any reason, including if the Carry-on Baggage cannot be safely stowed, or the Carry-on Baggage is not compliant with the Maximum Outside Linear Dimensions specified in section 2) above."
"Musical Instruments - Musical instruments may be carried as Checked Baggage or as Cabin Baggage subject to the provisions in D) above. As part of a Passenger’s one carry-on plus one personal item allowance and subject to UA’s Carry-on Baggage conditions specified in Section B 2) a) and b) above, a small musical instrument such as a violin or a guitar can be carried in lieu of a carry-on bag if the instrument can be stowed safely in an overhead bin or under the Passenger’s seat and there is space for its stowage at the time the Passenger boards. If the musical instrument appears too large or irregularly shaped to fit under the seat or in the overhead compartment, or, if at the time the customer boards the aircraft, there is no space to stow it, it will not be accepted for in cabin stowage and will be checked to the Passenger’s final destination and subject to the applicable checked-baggage and gate-checked handling charges. In the case of Basic Economy passengers, a small musical instrument may be carried on in addition to a personal item if it can be stowed safely in an overhead bin or under the Passenger’s seat and there is space for its stowage at the time the Passenger boards. A larger musical instrument brought to the gate as a carry-on by a Basic Economy passenger and any instrument that cannot fit under the Passenger’s seat or in open overhead bin space available at the time the Basic Economy passenger boards will be checked to the Passenger’s final destination and subject to the applicable checked-baggage and gate-checked handling charges. All musical instruments, whether carry-on or checked, should be in a hard sided case, and stringed instruments should have the strings loosened to protect the neck from damage due to expansion and contraction which result from temperature variations. Checked instruments cannot exceed 165 pounds and 150 linear inches (or the applicable weight/size restriction for the aircraft) and will be included in determining the Baggage Allowance, and when in excess (over 2 checked items), overweight or oversize (115 linear inches is considered oversized, and over 51 pounds (23.1 kg) is considered overweight), will be subject to the Excess, Oversize, and Overweight Baggage Charge. Except for certain International Carriage subject to the terms of the Montreal Convention, UA is not liable for damage to musical instruments or musical instrument cases."
from https://www.united.com/en/us/fly/contra ... ml#rule-23