MD-80 Series (DC-9-80) Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Workload; Troubleshooting
Aircraft Equipment Problem Less Severe
Aircraft Equipment Problem Dissipated; Flight Crew FLC complied w / Automation / Advisory; Flight Crew Landed in Emergency Condition; Flight Crew Took Evasive Action
Aircraft; Procedure
The First Officer was flying the act.  During level off at the cruise altitude FL240 the First Officer said the primary trim was not working.  Then he tried to use the alternate trim switches.  The trim did not move.  I then attempted to trim using the primary trim switches on the Captain yoke.  The trim did not move.  We consulted the QRH for stabilizer Inoperative In Flight.  After checking all referenced circuit breakers and the Stabilizer Trim (Red Guarded) were normal.   Step six requires a check of the primary longitudinal trim.  It operated normally.  The QRH says at this point to continue normal operation.  We were ready for descent to our filed destination at this time.  Although normal operation was restored; I felt it prudent to [advise ATC] and expedite our arrival.  We flew a visual approach and landed uneventfully.
The Captain [advised ATC] and First Officer landed aircraft uneventfully at the filed destination.
A MD-80 First Officer discovered both the Main and Alternate trim inoperative upon leveling at cruise. The QRH was completed but all systems appeared normal; then prior to descent both trim systems became operational. An uneventful landing ensued.