B737 inbound to hou accepts descent clearance for another aircraft.

Attributes
ACN	581689
Time
Date	200305
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : zhu.artcc
State Reference	TX
Altitude	msl bound lower : 21500 msl bound upper : 23000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zhu.artcc
Operator	common carrier : air carrier
Make Model Name	B737-200
Operating Under FAR Part	Part 121
Flight Phase	cruise : level cruise : enroute altitude change
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zhu.artcc
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	581689
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : instrument pilot : commercial
Experience	flight time last 90 days : 230 flight time total : 6500 flight time type : 2100
ASRS Report	581688
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : airborne less severe non adherence : clearance
Independent Detector	aircraft equipment : tcas other flight crewa
Resolutory Action	controller : issued new clearance controller : issued alert flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	Flight Crew Human Performance ATC Human Performance
Primary Problem	Flight Crew Human Performance

Narrative:

Captain was off ATC copying ATIS. First officer flying and working ATC. ATC gave clearance to descend to FL190 and turn to 080 degrees. Clearance was partially garbled. First officer read it back and started descent. I came on frequency to hear ATC give clearance to climb to FL230 and turn on 080 degrees 'immediately.' we complied with clearance. During turn, TA sounded. Another carrier flight #XX3 was in front of us going to iah and the clearance was his initially. Later when handed off to approach control, center controller thanked us for our help. But the fact is we read back the other carrier's clearance and initiated descent from FL230 to FL215 before correcting miscom. Both the ATC controller and our crew failed to notice the wrong readback. To make matters more complicated, the other carrier's crew read back one of our clrncs during this time.

Original NASA ASRS Text

Title: B737 INBOUND TO HOU ACCEPTS DSCNT CLRNC FOR ANOTHER ACFT.

Narrative: CAPT WAS OFF ATC COPYING ATIS. FO FLYING AND WORKING ATC. ATC GAVE CLRNC TO DSND TO FL190 AND TURN TO 080 DEGS. CLRNC WAS PARTIALLY GARBLED. FO READ IT BACK AND STARTED DSCNT. I CAME ON FREQ TO HEAR ATC GIVE CLRNC TO CLB TO FL230 AND TURN ON 080 DEGS 'IMMEDIATELY.' WE COMPLIED WITH CLRNC. DURING TURN, TA SOUNDED. ANOTHER CARRIER FLT #XX3 WAS IN FRONT OF US GOING TO IAH AND THE CLRNC WAS HIS INITIALLY. LATER WHEN HANDED OFF TO APCH CTL, CTR CTLR THANKED US FOR OUR HELP. BUT THE FACT IS WE READ BACK THE OTHER CARRIER'S CLRNC AND INITIATED DSCNT FROM FL230 TO FL215 BEFORE CORRECTING MISCOM. BOTH THE ATC CTLR AND OUR CREW FAILED TO NOTICE THE WRONG READBACK. TO MAKE MATTERS MORE COMPLICATED, THE OTHER CARRIER'S CREW READ BACK ONE OF OUR CLRNCS DURING THIS TIME.

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.