“Voluntary denied boarding” is a situation when a passenger voluntarily gives up their confirmed booking on a flight, at the airline’s request, in exchange for benefits offered by the airline. Passengers who volunteer to be denied boarding are not entitled to compensation beyond what has been offered by the airline and accepted by the passenger.
“Involuntary denied boarding” is a situation where the airline refuses to carry a passenger on the flight on which the passenger holds a confirmed booking, even though they presented themselves for check-in and boarding on time (except where there are reasonable grounds to deny them boarding, such as reasons of health, security, or inadequate travel documentation). Passengers who are involuntarily denied boarding are entitled to prescribed compensation.
Under the US regulations, the amount of denied boarding compensation is based on the difference between the originally planned arrival time and the planned arrival time of the alternative transportation at the first scheduled stopover, or if none, the airport of final destination.
Denied boarding compensation must be paid immediately, on the day and at the airport where the incident takes place. If the passenger’s alternative transportation departs before payment can be prepared, the airline must pay by mail or other means within 24 hours.
The airline is not required to pay denied boarding compensation under the US regulations if the substitution of the aircraft was required for “operational or safety reasons” (a rather vague notion).