***POSITIVELY*** DON'T DO THIS !!!!!!!!!!Per Delta rules if you have made a reservation on a flight YOU MAY NOT CANCEL THAT RESERVATION AND FLY STANDBY !You can cancel the reservation "BUT DO NOT FLY STANDBY ON THAT FLIGHT" !Big deal *YES* really the maximum penalty could be loss of all standby privileges forever or whatever period Delta sets !Depending on other circumstances you also could be "FIRED" if your action was intentional and willful !If your intent is to get on this flight and you are listed as Standby and the standby situation is turning sour you may takean OPEN NON reservation ticket and use it to trump the non-rev standby situation depending on timing - but clear this with theGate Agent before boarding has commenced. What you are doing is making a last minute reservation and abandoning thestandby program. Once done you can not go back if space is made available. If other full fare standbys are awaiting a seatyou would be placed in que order after them. Note: If the flight looks that bad you should have made a reservation in first place ! So this question as posed is answered !