Large transport has lost communication due to FLIP flop switch flipping to wrong frequency.

Attributes
ACN	269318
Time
Date	199404
Day	Wed
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : ord
State Reference	IL
Altitude	msl bound lower : 10000 msl bound upper : 10000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : ord
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 80 flight time total : 15000 flight time type : 350
ASRS Report	269318
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : instrument pilot : commercial
Events
Anomaly	non adherence : clearance other anomaly other
Independent Detector	other flight crewa
Resolutory Action	other
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation other

Narrative:

Switched to ord approach control approximately 15-20 mi northwest of field. Approaching the ord VOR, I noticed that we had not been slowed below 250 KTS and the controller's voice was different from the one who answered when I checked on the frequency. TCASII indicated we were following the same path as the aircraft we had been following, so I wasn't overly concerned. I checked the frequency and saw that the 'FLIP-flop' switch was back on the previous frequency. After switching back to approach frequency. (Very busy -- hard to get word in edgewise) controller informed us she had been trying for 20 mi to reach us. No conflicting traffic. Have no idea how switch got moved to the previous frequency. Fortunately, the time of lost contact was relatively short, however the area of the occurrence could not have been more critical (ord). TCASII, in this instance, proved itself to be an invaluable tool, particularly after discovering the problem, in assuring no conflicts with other traffic in the area. No deviation from the intended flight path was necessary.

Original NASA ASRS Text

Title: LGT HAS LOST COM DUE TO FLIP FLOP SWITCH FLIPPING TO WRONG FREQ.

Narrative: SWITCHED TO ORD APCH CTL APPROX 15-20 MI NW OF FIELD. APCHING THE ORD VOR, I NOTICED THAT WE HAD NOT BEEN SLOWED BELOW 250 KTS AND THE CTLR'S VOICE WAS DIFFERENT FROM THE ONE WHO ANSWERED WHEN I CHKED ON THE FREQ. TCASII INDICATED WE WERE FOLLOWING THE SAME PATH AS THE ACFT WE HAD BEEN FOLLOWING, SO I WASN'T OVERLY CONCERNED. I CHKED THE FREQ AND SAW THAT THE 'FLIP-FLOP' SWITCH WAS BACK ON THE PREVIOUS FREQ. AFTER SWITCHING BACK TO APCH FREQ. (VERY BUSY -- HARD TO GET WORD IN EDGEWISE) CTLR INFORMED US SHE HAD BEEN TRYING FOR 20 MI TO REACH US. NO CONFLICTING TFC. HAVE NO IDEA HOW SWITCH GOT MOVED TO THE PREVIOUS FREQ. FORTUNATELY, THE TIME OF LOST CONTACT WAS RELATIVELY SHORT, HOWEVER THE AREA OF THE OCCURRENCE COULD NOT HAVE BEEN MORE CRITICAL (ORD). TCASII, IN THIS INSTANCE, PROVED ITSELF TO BE AN INVALUABLE TOOL, PARTICULARLY AFTER DISCOVERING THE PROBLEM, IN ASSURING NO CONFLICTS WITH OTHER TFC IN THE AREA. NO DEV FROM THE INTENDED FLT PATH WAS NECESSARY.

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.