Narrative:

While on radar vectors to iad, and after checking in with ZNY on frequency 132.5, we were given a vector of 160 degrees while maintaining 11000 ft. After about 10 mins, we queried the controller as to how much longer we could expect to remain on the 160 degree heading. He responded by telling us that we were now on 133.5 and should instead be on 132.5 (our assigned frequency). This caused obvious confusion as to how we inadvertently would up on the wrong frequency. Both the first officer and I agreed that neither of us had touched the communication radio in use (captain's side -- communication #1). However, being an EFIS equipped aircraft using radios (navigation/communication) with digital readouts and 'automatic tuning' capability, we began to investigate possible problems with the radios. The frequency display indicated the frequency in amber numerals -- a usual indication that the radio had 'automatic-tuned' itself instead of the normal white numerals shown when the radio is tuned manually by the pilot. Unfortunately, neither the first officer nor myself were aware that this was possible on the 'communication' side of the unit. 'Automatic tuning' is usually only possible on the 'navigation' portion of the radio. The only other time amber numerals are displayed is when there is some kind of error within the unit itself. After investigation, we were unable to explain the occurrence or the amber readout. No known traffic conflicts were observed or reported. Upon finally getting back to 132.5, the controller simply continued vectoring us back towards iad. We were off frequency probably 10 mins maximum. Callback conversation with reporter revealed the following information: reporter indicated that the aircraft has a third VHF radio. The tuning head for this radio can be substituted into VHF 1 or 2 if they should fail. The crew inadvertently bumped the xfer switch without realizing it. When returned to its proper position, operation was normal.

Related reports:

Google
 

Original NASA ASRS Text

Title: JS41 CREW LOST COM WITH ZNY IN CLASS E AIRSPACE.

Narrative: WHILE ON RADAR VECTORS TO IAD, AND AFTER CHKING IN WITH ZNY ON FREQ 132.5, WE WERE GIVEN A VECTOR OF 160 DEGS WHILE MAINTAINING 11000 FT. AFTER ABOUT 10 MINS, WE QUERIED THE CTLR AS TO HOW MUCH LONGER WE COULD EXPECT TO REMAIN ON THE 160 DEG HDG. HE RESPONDED BY TELLING US THAT WE WERE NOW ON 133.5 AND SHOULD INSTEAD BE ON 132.5 (OUR ASSIGNED FREQ). THIS CAUSED OBVIOUS CONFUSION AS TO HOW WE INADVERTENTLY WOULD UP ON THE WRONG FREQ. BOTH THE FO AND I AGREED THAT NEITHER OF US HAD TOUCHED THE COM RADIO IN USE (CAPT'S SIDE -- COM #1). HOWEVER, BEING AN EFIS EQUIPPED ACFT USING RADIOS (NAV/COM) WITH DIGITAL READOUTS AND 'AUTOMATIC TUNING' CAPABILITY, WE BEGAN TO INVESTIGATE POSSIBLE PROBS WITH THE RADIOS. THE FREQ DISPLAY INDICATED THE FREQ IN AMBER NUMERALS -- A USUAL INDICATION THAT THE RADIO HAD 'AUTO-TUNED' ITSELF INSTEAD OF THE NORMAL WHITE NUMERALS SHOWN WHEN THE RADIO IS TUNED MANUALLY BY THE PLT. UNFORTUNATELY, NEITHER THE FO NOR MYSELF WERE AWARE THAT THIS WAS POSSIBLE ON THE 'COM' SIDE OF THE UNIT. 'AUTO TUNING' IS USUALLY ONLY POSSIBLE ON THE 'NAV' PORTION OF THE RADIO. THE ONLY OTHER TIME AMBER NUMERALS ARE DISPLAYED IS WHEN THERE IS SOME KIND OF ERROR WITHIN THE UNIT ITSELF. AFTER INVESTIGATION, WE WERE UNABLE TO EXPLAIN THE OCCURRENCE OR THE AMBER READOUT. NO KNOWN TFC CONFLICTS WERE OBSERVED OR RPTED. UPON FINALLY GETTING BACK TO 132.5, THE CTLR SIMPLY CONTINUED VECTORING US BACK TOWARDS IAD. WE WERE OFF FREQ PROBABLY 10 MINS MAX. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR INDICATED THAT THE ACFT HAS A THIRD VHF RADIO. THE TUNING HEAD FOR THIS RADIO CAN BE SUBSTITUTED INTO VHF 1 OR 2 IF THEY SHOULD FAIL. THE CREW INADVERTENTLY BUMPED THE XFER SWITCH WITHOUT REALIZING IT. WHEN RETURNED TO ITS PROPER POS, OP WAS NORMAL.

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.