Reply to wrong call sing results in a heading track altitude deviation.

Attributes
ACN	268344
Time
Date	199404
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : gmn
State Reference	CA
Altitude	msl bound lower : 22000 msl bound upper : 28000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zla
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	climbout : intermediate altitude cruise other
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
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 225 flight time total : 8000 flight time type : 3000
ASRS Report	268344
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 140 flight time total : 13000 flight time type : 0
ASRS Report	268345
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other other spatial deviation
Independent Detector	other other : unspecified
Resolutory Action	controller : issued new clearance flight crew : returned to intended course or assigned course
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

There were 3 aircraft on frequency with similar sounding call signs. We all had been 'stepping on' each other's radio xmissions and on center. We thought we heard a 30 degree right turn and climb to FL280 (from an intermediate stop at FL220). We read back the clearance and began to execute it. At this time, a company flight told center that someone had taken their clearance. Center then gave us clearance to FL280. We then asked for a confirmation of heading he wanted us on and were told to 'fly on course' at which point we discontinued the right turn and turned back left. Several factors contributed to this incident: several aircraft on the same frequency -- all of which were getting 'stair stepped' clrncs to their final cruise altitude. We were closing to 10 NM on the aircraft in front of us and were anticipating a vector off course for continued climb. Several radio xmissions were blocked by other aircraft because a lot of instructions were being given at the time. Supplemental information from acn 268345: the call sign of the other aircraft was very similar to the call sign on our last leg. We were being 'stair stepped' behind a preceding aircraft and could see on the TCASII that we were losing our 10 mi separation and were therefore anticipating some action very soon by the controller. In other words, I was cocked for a clearance. This was the seventh and last leg of the day.

Original NASA ASRS Text

Title: REPLY TO WRONG CALL SING RESULTS IN A HDG TRACK ALTDEV.

Narrative: THERE WERE 3 ACFT ON FREQ WITH SIMILAR SOUNDING CALL SIGNS. WE ALL HAD BEEN 'STEPPING ON' EACH OTHER'S RADIO XMISSIONS AND ON CTR. WE THOUGHT WE HEARD A 30 DEG R TURN AND CLB TO FL280 (FROM AN INTERMEDIATE STOP AT FL220). WE READ BACK THE CLRNC AND BEGAN TO EXECUTE IT. AT THIS TIME, A COMPANY FLT TOLD CTR THAT SOMEONE HAD TAKEN THEIR CLRNC. CTR THEN GAVE US CLRNC TO FL280. WE THEN ASKED FOR A CONFIRMATION OF HDG HE WANTED US ON AND WERE TOLD TO 'FLY ON COURSE' AT WHICH POINT WE DISCONTINUED THE R TURN AND TURNED BACK L. SEVERAL FACTORS CONTRIBUTED TO THIS INCIDENT: SEVERAL ACFT ON THE SAME FREQ -- ALL OF WHICH WERE GETTING 'STAIR STEPPED' CLRNCS TO THEIR FINAL CRUISE ALT. WE WERE CLOSING TO 10 NM ON THE ACFT IN FRONT OF US AND WERE ANTICIPATING A VECTOR OFF COURSE FOR CONTINUED CLB. SEVERAL RADIO XMISSIONS WERE BLOCKED BY OTHER ACFT BECAUSE A LOT OF INSTRUCTIONS WERE BEING GIVEN AT THE TIME. SUPPLEMENTAL INFO FROM ACN 268345: THE CALL SIGN OF THE OTHER ACFT WAS VERY SIMILAR TO THE CALL SIGN ON OUR LAST LEG. WE WERE BEING 'STAIR STEPPED' BEHIND A PRECEDING ACFT AND COULD SEE ON THE TCASII THAT WE WERE LOSING OUR 10 MI SEPARATION AND WERE THEREFORE ANTICIPATING SOME ACTION VERY SOON BY THE CTLR. IN OTHER WORDS, I WAS COCKED FOR A CLRNC. THIS WAS THE SEVENTH AND LAST LEG OF THE DAY.

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.