Narrative:

While en route from efd to nbg I was acting as PNF (sic) and working the communication radios. Approximately 80 NM out of nbg and in level assigned cruise of 17000 ft MSL, I was given a handoff to the next controller which I read back. I then reached up and erased the existing ZHU frequency and subsequently forgot the assigned handoff frequency. The PIC then stated he heard the frequency and reached over and dialed the supposed frequency in. It was not a valid frequency. The PIC then instructed me to take control of the aircraft while he 'looked up' the proper frequency. He dialed it in and took the plane as PF again. I then checked in with the controller by stating 'aircraft identify with you at 17000 ft.' the controller responded by saying 'roger.' after a short duration of time, the same controller gave us a clearance to descend from 17000 ft to 2000 ft at pilot's discretion. The PF then started the descent. There seemed to be some confusion with the controller and another aircraft which we could not hear (we could only hear the controller responding to this other aircraft that this instruction was for our aircraft identify, not him. I then again verified that the clearance was indeed for us whereupon the controller replied 'affirmative.' this controller handed us off to our final controller (before tower) whereupon we were instructed by ZHU to call them by landline, which we subsequently did. They inquired why we descended to 2000 ft unauthorized. I think the PIC possibly looked up the wrong frequency and either called lafayette approach or new orleans approach who didn't quite expect us at that time and got us confused with another aircraft. However, I did confirm our clearance by readback and even called back again to reconfirm.

Related reports:

Google
 

Original NASA ASRS Text

Title: FLC OF SMT GOV CHARTER ACFT TUNES THE WRONG FREQ AND CREATES CONFUSION AT ATC. RESULTING CLRNC IS CONFUSING TO FLC. ALTDEV.

Narrative: WHILE ENRTE FROM EFD TO NBG I WAS ACTING AS PNF (SIC) AND WORKING THE COM RADIOS. APPROX 80 NM OUT OF NBG AND IN LEVEL ASSIGNED CRUISE OF 17000 FT MSL, I WAS GIVEN A HDOF TO THE NEXT CTLR WHICH I READ BACK. I THEN REACHED UP AND ERASED THE EXISTING ZHU FREQ AND SUBSEQUENTLY FORGOT THE ASSIGNED HDOF FREQ. THE PIC THEN STATED HE HEARD THE FREQ AND REACHED OVER AND DIALED THE SUPPOSED FREQ IN. IT WAS NOT A VALID FREQ. THE PIC THEN INSTRUCTED ME TO TAKE CTL OF THE ACFT WHILE HE 'LOOKED UP' THE PROPER FREQ. HE DIALED IT IN AND TOOK THE PLANE AS PF AGAIN. I THEN CHKED IN WITH THE CTLR BY STATING 'ACFT IDENT WITH YOU AT 17000 FT.' THE CTLR RESPONDED BY SAYING 'ROGER.' AFTER A SHORT DURATION OF TIME, THE SAME CTLR GAVE US A CLRNC TO DSND FROM 17000 FT TO 2000 FT AT PLT'S DISCRETION. THE PF THEN STARTED THE DSCNT. THERE SEEMED TO BE SOME CONFUSION WITH THE CTLR AND ANOTHER ACFT WHICH WE COULD NOT HEAR (WE COULD ONLY HEAR THE CTLR RESPONDING TO THIS OTHER ACFT THAT THIS INSTRUCTION WAS FOR OUR ACFT IDENT, NOT HIM. I THEN AGAIN VERIFIED THAT THE CLRNC WAS INDEED FOR US WHEREUPON THE CTLR REPLIED 'AFFIRMATIVE.' THIS CTLR HANDED US OFF TO OUR FINAL CTLR (BEFORE TWR) WHEREUPON WE WERE INSTRUCTED BY ZHU TO CALL THEM BY LANDLINE, WHICH WE SUBSEQUENTLY DID. THEY INQUIRED WHY WE DSNDED TO 2000 FT UNAUTH. I THINK THE PIC POSSIBLY LOOKED UP THE WRONG FREQ AND EITHER CALLED LAFAYETTE APCH OR NEW ORLEANS APCH WHO DIDN'T QUITE EXPECT US AT THAT TIME AND GOT US CONFUSED WITH ANOTHER ACFT. HOWEVER, I DID CONFIRM OUR CLRNC BY READBACK AND EVEN CALLED BACK AGAIN TO RECONFIRM.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.