An air carrier flight crew used the wrong switch position to transmit to approach control and tower.

Attributes
ACN	330950
Time
Date	199603
Day	Sun
Local Time Of Day	0001 To 0600
Place
Locale Reference	airport : iad
State Reference	VA
Altitude	msl bound lower : 1900 msl bound upper : 2000
Aircraft 1
Controlling Facilities	tracon : iad tower : iad
Operator	common carrier : air carrier
Make Model Name	B767 Undifferentiated or Other Model
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
ASRS Report	330950
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	other anomaly other
Independent Detector	other controllera other flight crewa
Resolutory Action	none taken : detected after the fact
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

After approach clearance instructed to change over to tower and call at mkr. I acknowledged but did so using the intercom side of control wheel switch. I heard sidetone and assumed I went out but did not wait for anything further from approach. I made a call to tower, again on the intercom. Heard sidetone and got busy with checklist and monitor practice autoland, not realizing I didn't get response from tower. Then tower calls quite huffy wanting to know why I didn't acknowledge approach control handoff and call him. We were cleared to land. Nothing else was said and during taxi in I realized what had happened. Apparently when tower called I used the proper side of switch without thinking about it. No wonder I didn't know what he was talking about at the time. I'll have to remember to turn down intervolume when not in use.

Original NASA ASRS Text

Title: AN ACR FLC USED THE WRONG SWITCH POS TO XMIT TO APCH CTL AND TWR.

Narrative: AFTER APCH CLRNC INSTRUCTED TO CHANGE OVER TO TWR AND CALL AT MKR. I ACKNOWLEDGED BUT DID SO USING THE INTERCOM SIDE OF CTL WHEEL SWITCH. I HEARD SIDETONE AND ASSUMED I WENT OUT BUT DID NOT WAIT FOR ANYTHING FURTHER FROM APCH. I MADE A CALL TO TWR, AGAIN ON THE INTERCOM. HEARD SIDETONE AND GOT BUSY WITH CHKLIST AND MONITOR PRACTICE AUTOLAND, NOT REALIZING I DIDN'T GET RESPONSE FROM TWR. THEN TWR CALLS QUITE HUFFY WANTING TO KNOW WHY I DIDN'T ACKNOWLEDGE APCH CTL HDOF AND CALL HIM. WE WERE CLRED TO LAND. NOTHING ELSE WAS SAID AND DURING TAXI IN I REALIZED WHAT HAD HAPPENED. APPARENTLY WHEN TWR CALLED I USED THE PROPER SIDE OF SWITCH WITHOUT THINKING ABOUT IT. NO WONDER I DIDN'T KNOW WHAT HE WAS TALKING ABOUT AT THE TIME. I'LL HAVE TO REMEMBER TO TURN DOWN INTERVOLUME WHEN NOT IN USE.

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.