Similar call signs air carrier X unauthorized descent from assigned altitude.

Attributes
ACN	266076
Time
Date	199403
Day	Wed
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : pxv
State Reference	IN
Altitude	msl bound lower : 27000 msl bound upper : 27000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zme
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	cruise other descent other
Route In Use	enroute : direct
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 14000
ASRS Report	266076
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 10000 flight time type : 3000
ASRS Report	266942
Events
Anomaly	altitude deviation : excursion from assigned altitude other anomaly other
Independent Detector	other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

We were air carrier 'X50.' we heard a descent to FL240. We were currently at FL270. We read back the clearance to descend to FL240 and started to descend. At FL268 air carrier 'XY50' called ATC and advised ATC that another aircraft had acknowledged their clearance to descend to FL240. We immediately climbed back to FL270 and advised ATC (ZME). ZME advised that there was traffic 12 O'clock at FL260, 10 mi ahead. Radio xmissions appear to be the most dangerous part of ATC today. There are too many similar call signs and too much radio traffic causing interference on radio frequencys.

Original NASA ASRS Text

Title: SIMILAR CALL SIGNS ACR X UNAUTH DSCNT FROM ASSIGNED ALT.

Narrative: WE WERE ACR 'X50.' WE HEARD A DSCNT TO FL240. WE WERE CURRENTLY AT FL270. WE READ BACK THE CLRNC TO DSND TO FL240 AND STARTED TO DSND. AT FL268 ACR 'XY50' CALLED ATC AND ADVISED ATC THAT ANOTHER ACFT HAD ACKNOWLEDGED THEIR CLRNC TO DSND TO FL240. WE IMMEDIATELY CLBED BACK TO FL270 AND ADVISED ATC (ZME). ZME ADVISED THAT THERE WAS TFC 12 O'CLOCK AT FL260, 10 MI AHEAD. RADIO XMISSIONS APPEAR TO BE THE MOST DANGEROUS PART OF ATC TODAY. THERE ARE TOO MANY SIMILAR CALL SIGNS AND TOO MUCH RADIO TFC CAUSING INTERFERENCE ON RADIO FREQS.

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.