Narrative:

2 aircraft owned by the same company climb off kansas city. The 2 aircraft have similar call signs. 1 of the aircraft is issued a clearance to climb to a higher altitude. Both aircraft acknowledge the clearance. The second aircraft is then told to maintain his present altitude. Slightly later cpr X is cleared to an even higher altitude. This time only the second cpr Y acknowledges. The error is not noticed and the aircraft starts to climb through the altitude of a third air carrier Z that cpr Y has been issued traffic on (and told to expect higher when clear of). The error is discovered when the cpr Y is observed 500 ft high. Cpr Y was then issued an 'immediate' turn and descent clearance. I believe the situation occurred due to 2 reasons: I never specifically told the 2 aircraft to 'be careful' of similar call signs and I assumed, after catching the first mistake, they would not make the same mistake again. The only preventive measure I can suggest is to tell the aircraft to listen harder and/or repeat all clrncs at least twice. Supplemental information from acn 190097. Had left mke in cpr Y eastbound to hpn. As we were climbing out we were given different altitudes to stop at in our climb. We were stopped at 270 for traffic. Some time later I saw an airliner pass overhead that looked 2000-3000 ft above. Short time later the controller said cpr climb and maintain FL310. We waited a few seconds before answering because our company aircraft cpr Z was also on the frequency. My copilot answered climb to 310 cpr Y. The controller didn't respond with any other instructions and the crew of cpr X said they (crew) didn't respond to the climb clearance since the controller never responded back to anything differently. I am not sure but I think a short time later the controller issued cpr X to climb to 350, and I think shortly thereafter he asked cpr Y what our altitude was. My copilot responded 28300 for 310. I think the controller asked what altitude we were climbing to and we responded 310. At this time we were told to descend to 270 immediately. During this time we were also told to turn left to 360 degree immediately which I did in approximately 45 degree bank, which resulted in approximately 4000 FPM descent. As we got to 270 we were asked if we were on 360 heading we responded affirmative. Short time later we were cleared back eastbound to continue our climb. The controller never mentioned if we had gotten close to another aircraft or not, and we never saw another aircraft. Some contributing factors may have been our company crp X on the frequency. We had been called crp X previously on this flight and responded the same way as above without any problems, but I don't think our company crp X was on the frequency yet. Similar call signs are a problem for everyone. A possible solution would be the computer watching your data block for altitude deviations above/below your assigned altitude as programmed into the computer as the controller issues the clearance. Such as low altitude alerts issued by approach controllers around terrain and towers. I also thought the airliner that passed overhead was the traffic we had been stopped in our climb for, and thought he was in a climb too is why when originally issued traffic at 280 he appeared 2-3000 above us.

Related reports:

Google
 

Original NASA ASRS Text

Title: SIMILAR CALL SIGNS CPR Y RESPONDED TO CPR X CLRNC AND HAD LTSS FROM ACR Z. PLTDEV NON ADHERENCE TO ATC CLRNC. SYS ERROR CTLR FAILED TO HEAR WRONG ACFT READBACK CLRNC.

Narrative: 2 ACFT OWNED BY THE SAME COMPANY CLB OFF KANSAS CITY. THE 2 ACFT HAVE SIMILAR CALL SIGNS. 1 OF THE ACFT IS ISSUED A CLRNC TO CLB TO A HIGHER ALT. BOTH ACFT ACKNOWLEDGE THE CLRNC. THE SECOND ACFT IS THEN TOLD TO MAINTAIN HIS PRESENT ALT. SLIGHTLY LATER CPR X IS CLRED TO AN EVEN HIGHER ALT. THIS TIME ONLY THE SECOND CPR Y ACKNOWLEDGES. THE ERROR IS NOT NOTICED AND THE ACFT STARTS TO CLB THROUGH THE ALT OF A THIRD ACR Z THAT CPR Y HAS BEEN ISSUED TFC ON (AND TOLD TO EXPECT HIGHER WHEN CLR OF). THE ERROR IS DISCOVERED WHEN THE CPR Y IS OBSERVED 500 FT HIGH. CPR Y WAS THEN ISSUED AN 'IMMEDIATE' TURN AND DSCNT CLRNC. I BELIEVE THE SITUATION OCCURRED DUE TO 2 REASONS: I NEVER SPECIFICALLY TOLD THE 2 ACFT TO 'BE CAREFUL' OF SIMILAR CALL SIGNS AND I ASSUMED, AFTER CATCHING THE FIRST MISTAKE, THEY WOULD NOT MAKE THE SAME MISTAKE AGAIN. THE ONLY PREVENTIVE MEASURE I CAN SUGGEST IS TO TELL THE ACFT TO LISTEN HARDER AND/OR REPEAT ALL CLRNCS AT LEAST TWICE. SUPPLEMENTAL INFO FROM ACN 190097. HAD LEFT MKE IN CPR Y EBOUND TO HPN. AS WE WERE CLBING OUT WE WERE GIVEN DIFFERENT ALTS TO STOP AT IN OUR CLB. WE WERE STOPPED AT 270 FOR TFC. SOME TIME LATER I SAW AN AIRLINER PASS OVERHEAD THAT LOOKED 2000-3000 FT ABOVE. SHORT TIME LATER THE CTLR SAID CPR CLB AND MAINTAIN FL310. WE WAITED A FEW SECONDS BEFORE ANSWERING BECAUSE OUR COMPANY ACFT CPR Z WAS ALSO ON THE FREQ. MY COPLT ANSWERED CLB TO 310 CPR Y. THE CTLR DIDN'T RESPOND WITH ANY OTHER INSTRUCTIONS AND THE CREW OF CPR X SAID THEY (CREW) DIDN'T RESPOND TO THE CLB CLRNC SINCE THE CTLR NEVER RESPONDED BACK TO ANYTHING DIFFERENTLY. I AM NOT SURE BUT I THINK A SHORT TIME LATER THE CTLR ISSUED CPR X TO CLB TO 350, AND I THINK SHORTLY THEREAFTER HE ASKED CPR Y WHAT OUR ALT WAS. MY COPLT RESPONDED 28300 FOR 310. I THINK THE CTLR ASKED WHAT ALT WE WERE CLBING TO AND WE RESPONDED 310. AT THIS TIME WE WERE TOLD TO DSND TO 270 IMMEDIATELY. DURING THIS TIME WE WERE ALSO TOLD TO TURN L TO 360 DEG IMMEDIATELY WHICH I DID IN APPROX 45 DEG BANK, WHICH RESULTED IN APPROX 4000 FPM DSCNT. AS WE GOT TO 270 WE WERE ASKED IF WE WERE ON 360 HDG WE RESPONDED AFFIRMATIVE. SHORT TIME LATER WE WERE CLRED BACK EBOUND TO CONTINUE OUR CLB. THE CTLR NEVER MENTIONED IF WE HAD GOTTEN CLOSE TO ANOTHER ACFT OR NOT, AND WE NEVER SAW ANOTHER ACFT. SOME CONTRIBUTING FACTORS MAY HAVE BEEN OUR COMPANY CRP X ON THE FREQ. WE HAD BEEN CALLED CRP X PREVIOUSLY ON THIS FLT AND RESPONDED THE SAME WAY AS ABOVE WITHOUT ANY PROBLEMS, BUT I DON'T THINK OUR COMPANY CRP X WAS ON THE FREQ YET. SIMILAR CALL SIGNS ARE A PROBLEM FOR EVERYONE. A POSSIBLE SOLUTION WOULD BE THE COMPUTER WATCHING YOUR DATA BLOCK FOR ALT DEVS ABOVE/BELOW YOUR ASSIGNED ALT AS PROGRAMMED INTO THE COMPUTER AS THE CTLR ISSUES THE CLRNC. SUCH AS LOW ALT ALERTS ISSUED BY APCH CTLRS AROUND TERRAIN AND TWRS. I ALSO THOUGHT THE AIRLINER THAT PASSED OVERHEAD WAS THE TFC WE HAD BEEN STOPPED IN OUR CLB FOR, AND THOUGHT HE WAS IN A CLB TOO IS WHY WHEN ORIGINALLY ISSUED TFC AT 280 HE APPEARED 2-3000 ABOVE US.

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.