Communications error and similar call signs leads to pilot deviation.

Attributes
ACN	295971
Time
Date	199502
Day	Tue
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : cvg
State Reference	OH
Altitude	msl bound lower : 19500 msl bound upper : 24000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zid
Operator	common carrier : air carrier
Make Model Name	DC-8 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	descent other
Route In Use	arrival other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 120 flight time total : 15100 flight time type : 4500
ASRS Report	295971
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : cfi pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 120 flight time total : 6500 flight time type : 2500
ASRS Report	295750
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance non adherence : far other anomaly other
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

This incident occurred, I believe, as a result of an overloaded and overworked ATC system. The entire flight was constant heading changes, radials to intercept altitude and airspeed changes. For example, shortly after handoff to ZOB we thought we heard 'climb to FL270.' between being stepped on and the controller working more than 1 frequency, it took 4 attempts on our part to verify our clearance. We were at our cruise altitude of FL310 on ZID and given a pilot's discretion to FL240. I can't recall for sure but I think we were handed off to another controller and cleared to 13000 ft, and we started descent. It would be impossible to recall times, headings, airspeed changes, etc with any degree of accuracy. During this time we commented among ourselves there didn't seem to be any kind of flow being established. We could visually see several aircraft, seemingly all headed in different directions at various altitudes. At some point we heard 'maintain your altitude.' we leveled off and maintained FL195 and informed the controller. At no time were we given TA's. In fact, nothing was said until approximately 5 hours later when a company supervisor approached me concerning this incident. Could we have accepted a clearance intended for someone else? Possibly. If so, the controller didn't catch the error and this has happened many times inbound to sdf. Did we read a clearance back wrong? Possibly. We weren't corrected. Could the controller have thought one thing and said another or been thinking one flight number and issued a clearance to another? I don't know the answer. What I do know is the constant stream of altitude, airspeed and heading changes being given every night inbound to louisville. Contributing factor: many company flight numbers are very similar. A comprehensive and realistic review of sdf arrival procedures needs to be conducted. To include ZID, sdf arrival and company possibly adjoining ctrs too. If we did approach another aircraft, which I am not questioning, it's only a matter of time before it happens again.

Original NASA ASRS Text

Title: COMS ERROR AND SIMILAR CALL SIGNS LEADS TO PLTDEV.

Narrative: THIS INCIDENT OCCURRED, I BELIEVE, AS A RESULT OF AN OVERLOADED AND OVERWORKED ATC SYS. THE ENTIRE FLT WAS CONSTANT HDG CHANGES, RADIALS TO INTERCEPT ALT AND AIRSPD CHANGES. FOR EXAMPLE, SHORTLY AFTER HDOF TO ZOB WE THOUGHT WE HEARD 'CLB TO FL270.' BTWN BEING STEPPED ON AND THE CTLR WORKING MORE THAN 1 FREQ, IT TOOK 4 ATTEMPTS ON OUR PART TO VERIFY OUR CLRNC. WE WERE AT OUR CRUISE ALT OF FL310 ON ZID AND GIVEN A PLT'S DISCRETION TO FL240. I CAN'T RECALL FOR SURE BUT I THINK WE WERE HANDED OFF TO ANOTHER CTLR AND CLRED TO 13000 FT, AND WE STARTED DSCNT. IT WOULD BE IMPOSSIBLE TO RECALL TIMES, HDGS, AIRSPD CHANGES, ETC WITH ANY DEG OF ACCURACY. DURING THIS TIME WE COMMENTED AMONG OURSELVES THERE DIDN'T SEEM TO BE ANY KIND OF FLOW BEING ESTABLISHED. WE COULD VISUALLY SEE SEVERAL ACFT, SEEMINGLY ALL HEADED IN DIFFERENT DIRECTIONS AT VARIOUS ALTS. AT SOME POINT WE HEARD 'MAINTAIN YOUR ALT.' WE LEVELED OFF AND MAINTAINED FL195 AND INFORMED THE CTLR. AT NO TIME WERE WE GIVEN TA'S. IN FACT, NOTHING WAS SAID UNTIL APPROX 5 HRS LATER WHEN A COMPANY SUPVR APCHED ME CONCERNING THIS INCIDENT. COULD WE HAVE ACCEPTED A CLRNC INTENDED FOR SOMEONE ELSE? POSSIBLY. IF SO, THE CTLR DIDN'T CATCH THE ERROR AND THIS HAS HAPPENED MANY TIMES INBOUND TO SDF. DID WE READ A CLRNC BACK WRONG? POSSIBLY. WE WEREN'T CORRECTED. COULD THE CTLR HAVE THOUGHT ONE THING AND SAID ANOTHER OR BEEN THINKING ONE FLT NUMBER AND ISSUED A CLRNC TO ANOTHER? I DON'T KNOW THE ANSWER. WHAT I DO KNOW IS THE CONSTANT STREAM OF ALT, AIRSPD AND HDG CHANGES BEING GIVEN EVERY NIGHT INBOUND TO LOUISVILLE. CONTRIBUTING FACTOR: MANY COMPANY FLT NUMBERS ARE VERY SIMILAR. A COMPREHENSIVE AND REALISTIC REVIEW OF SDF ARR PROCS NEEDS TO BE CONDUCTED. TO INCLUDE ZID, SDF ARR AND COMPANY POSSIBLY ADJOINING CTRS TOO. IF WE DID APCH ANOTHER ACFT, WHICH I AM NOT QUESTIONING, IT'S ONLY A MATTER OF TIME BEFORE IT HAPPENS AGAIN.

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.