USA-based United Airlines is testing a 'Flex-Schedule' program that will email passengers ahead of time on certain flights and ask them if they will consider changing flights in return for a travel voucher worth up to US$250.

The airline will ask passengers if they're willing to take an earlier or later flight, but it won't ask them to change dates or airports.

 

The Flex-Schedule program will only be open to frequent flyer members who book directly on United.com and have opted in to receiving marketing emails.

 

US airlines currently offer passengers seat upgrades or US$1,000 cash - or more - if they give up their seats on overbooked flights and take a later flight. If there are no volunteers, passengers may be involuntarily 'bumped'. 

 

Commentators have given the United plan mixed reviews. Its critics say US$250 may not be enough.