Best flight crew regains communication after radio automatic switches frequency in ZMA airspace.

Attributes
ACN	427690
Time
Date	199902
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : cyy
State Reference	FL
Altitude	msl bound lower : 26000 msl bound upper : 26000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	general aviation : corporate
Make Model Name	Starship Model 2000
Flight Phase	cruise other
Route In Use	arrival other
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : captain oversight : pic
Qualification	pilot : cfi
Experience	flight time last 90 days : 75 flight time total : 7500 flight time type : 1000
ASRS Report	427690
Person 2
Affiliation	Other
Function	flight crew : first officer
Qualification	pilot : commercial
Events
Anomaly	aircraft equipment problem : less severe other anomaly other
Independent Detector	other flight crewa
Resolutory Action	flight crew : overcame equipment problem
Consequence	Other
Supplementary
Air Traffic Incident	other

Narrative:

While en route at FL260 for some time, and approaching our arrival's initial fix to the airport, it seemed odd that ATC never handed us off. Upon closer examination and repeated attempts to establish communications, we noticed that the communication radio had, for some reason, autoxferred us back to our previous frequency, which the unit stores in 'recall.' luckily, no incident. From memory, I knew the proper frequency and we re- established communication and we were able to proceed normally, but these units sometimes seem to have a mind all their own! Callback conversation with reporter revealed the following information: the reporter states that he has seen this 'automatic switch' occur on one other occasion. After maintenance replaced the CDU, the problem did not recur. The reporter states that the communication radio is a collins proline 4 system.

Original NASA ASRS Text

Title: BEST FLC REGAINS COM AFTER RADIO AUTO SWITCHES FREQ IN ZMA AIRSPACE.

Narrative: WHILE ENRTE AT FL260 FOR SOME TIME, AND APCHING OUR ARR'S INITIAL FIX TO THE ARPT, IT SEEMED ODD THAT ATC NEVER HANDED US OFF. UPON CLOSER EXAMINATION AND REPEATED ATTEMPTS TO ESTABLISH COMS, WE NOTICED THAT THE COM RADIO HAD, FOR SOME REASON, AUTOXFERRED US BACK TO OUR PREVIOUS FREQ, WHICH THE UNIT STORES IN 'RECALL.' LUCKILY, NO INCIDENT. FROM MEMORY, I KNEW THE PROPER FREQ AND WE RE- ESTABLISHED COM AND WE WERE ABLE TO PROCEED NORMALLY, BUT THESE UNITS SOMETIMES SEEM TO HAVE A MIND ALL THEIR OWN! CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATES THAT HE HAS SEEN THIS 'AUTO SWITCH' OCCUR ON ONE OTHER OCCASION. AFTER MAINT REPLACED THE CDU, THE PROB DID NOT RECUR. THE RPTR STATES THAT THE COM RADIO IS A COLLINS PROLINE 4 SYS.

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.