Narrative:

Approximately 40 NM ahead of us on the same STAR at the same altitude, talking with the same ZME controller on the same frequency was a company aircraft with a call sign that began with the same digit as our call sign. The ZME controller issued a descent clearance to 10000 ft along with an additional request to expedite descent due to other traffic. The captain set 10000 ft on the MCP and initiated a descent at a rapid rate in order to comply with the ATC clearance. The first officer acknowledged the clearance by repeating the entire clearance back to ZME. Approximately 4 mi off our right (north of us) and approximately 1000 ft below us the TCASII idented opposite direction traffic. Almost immediately the first officer visually idented the traffic and continued to point it out as it passed 3-4 mi right of us and 1000 ft below us. As we passed the traffic we continued the descent. ZME called us and asked our altitude. The first officer answered that we were 13500 ft and descending. ZME then called our company aircraft ahead and asked them if they were descending to 10000 ft. They stated that they were. This sounded like an odd occurrence, so the first officer called ZME and asked for verification that clearance to 10000 ft was meant for our aircraft. ZME replied that the clearance was intended for the company aircraft ahead. The first officer then asked if we should return to 16000 ft. ZME told us not to. We continued to 10000 ft. Upon arrival in memphis, the captain telephoned ZME. The person answering the telephone stated that the clearance to 10000 ft was meant for the company aircraft ahead of us, and that someone was reviewing the tapes at that time. During the telephone conversation another person spoke in the backgnd stating that upon listening to the tapes he could hear both of the aircraft answering the clearance, and that apparently the aircraft ahead was more clear but that our readback lasted longer and was noticeable after the company aircraft ahead had ended their readback. The captain and the first officer both heard the clearance and understood the clearance to be for our call sign. According to ZME we misunderstood the call sign. We both acted in good faith. The captain complied with the clearance we honestly thought was meant for us, and the first officer read back the full clearance that we honestly thought was meant for us. What really caused this problem? The flight crew on both company aircraft heard the clearance and thought it was meant for them. Both crews responded to the clearance and acknowledged the clearance by reading it back. The problem was caused by misunderstanding the call sign, possibly due to radio interference, and by both of the readbacks of the clearance being transmitted at the same time. What can be done to prevent a recurrence or correct the situation? Obviously, all flcs have a responsibility to diligently listen to all radio calls and respond to them appropriately. Having 2 crew members in each cockpit both listening to the same radio xmissions should help to reduce the possibility of misunderstandings inherent to human shortcomings, but obviously cannot prevent them entirely, as evidenced by this situation. Furthermore, if the ATC controller noticed that 2 aircraft responded to the same clearance at the same time (as apparently the ZME person reviewing the tapes during the telephone call could hear that 2 aircraft transmitted at the same time) and had re-emphasized that the clearance in question was meant only for the intended aircraft, then we would not have left our altitude of 16000 ft. We found out afterward that our company aircraft ahead noticed that another transmission continued after they unkeyed their transmitter. Had they questioned this over the air, then we could have queried ATC about our clearance. Another contributing factor to this situation is that all of our company flts in the part of the country start with the same digit. If we had differing call signs then those differences would be more noticeable and distinguishable during radio xmissions. The best fix, however, may come with improved technology. Perhaps technology that can identify to all parties concerned that their transmission was covered up by another transmission, by sending clrncs to aircraft via text up-link, or by designing new radio technology that allows an aircraft's radio to receive only those ATC xmissions that are specifically directly at them. One final note: many airmen file NASA ASRS forms solely to take advantage of the immunity provisions. This airman has placed much thought into filling out the forms completely and answering the form's questions thoughtfully with the hope that some positive benefit will result.

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Original NASA ASRS Text

Title: THE CREW OF AN RJ85 RESPONDED TO ANOTHER ACFT'S DSCNT CLRNC.

Narrative: APPROX 40 NM AHEAD OF US ON THE SAME STAR AT THE SAME ALT, TALKING WITH THE SAME ZME CTLR ON THE SAME FREQ WAS A COMPANY ACFT WITH A CALL SIGN THAT BEGAN WITH THE SAME DIGIT AS OUR CALL SIGN. THE ZME CTLR ISSUED A DSCNT CLRNC TO 10000 FT ALONG WITH AN ADDITIONAL REQUEST TO EXPEDITE DSCNT DUE TO OTHER TFC. THE CAPT SET 10000 FT ON THE MCP AND INITIATED A DSCNT AT A RAPID RATE IN ORDER TO COMPLY WITH THE ATC CLRNC. THE FO ACKNOWLEDGED THE CLRNC BY REPEATING THE ENTIRE CLRNC BACK TO ZME. APPROX 4 MI OFF OUR R (N OF US) AND APPROX 1000 FT BELOW US THE TCASII IDENTED OPPOSITE DIRECTION TFC. ALMOST IMMEDIATELY THE FO VISUALLY IDENTED THE TFC AND CONTINUED TO POINT IT OUT AS IT PASSED 3-4 MI R OF US AND 1000 FT BELOW US. AS WE PASSED THE TFC WE CONTINUED THE DSCNT. ZME CALLED US AND ASKED OUR ALT. THE FO ANSWERED THAT WE WERE 13500 FT AND DSNDING. ZME THEN CALLED OUR COMPANY ACFT AHEAD AND ASKED THEM IF THEY WERE DSNDING TO 10000 FT. THEY STATED THAT THEY WERE. THIS SOUNDED LIKE AN ODD OCCURRENCE, SO THE FO CALLED ZME AND ASKED FOR VERIFICATION THAT CLRNC TO 10000 FT WAS MEANT FOR OUR ACFT. ZME REPLIED THAT THE CLRNC WAS INTENDED FOR THE COMPANY ACFT AHEAD. THE FO THEN ASKED IF WE SHOULD RETURN TO 16000 FT. ZME TOLD US NOT TO. WE CONTINUED TO 10000 FT. UPON ARR IN MEMPHIS, THE CAPT TELEPHONED ZME. THE PERSON ANSWERING THE TELEPHONE STATED THAT THE CLRNC TO 10000 FT WAS MEANT FOR THE COMPANY ACFT AHEAD OF US, AND THAT SOMEONE WAS REVIEWING THE TAPES AT THAT TIME. DURING THE TELEPHONE CONVERSATION ANOTHER PERSON SPOKE IN THE BACKGND STATING THAT UPON LISTENING TO THE TAPES HE COULD HEAR BOTH OF THE ACFT ANSWERING THE CLRNC, AND THAT APPARENTLY THE ACFT AHEAD WAS MORE CLR BUT THAT OUR READBACK LASTED LONGER AND WAS NOTICEABLE AFTER THE COMPANY ACFT AHEAD HAD ENDED THEIR READBACK. THE CAPT AND THE FO BOTH HEARD THE CLRNC AND UNDERSTOOD THE CLRNC TO BE FOR OUR CALL SIGN. ACCORDING TO ZME WE MISUNDERSTOOD THE CALL SIGN. WE BOTH ACTED IN GOOD FAITH. THE CAPT COMPLIED WITH THE CLRNC WE HONESTLY THOUGHT WAS MEANT FOR US, AND THE FO READ BACK THE FULL CLRNC THAT WE HONESTLY THOUGHT WAS MEANT FOR US. WHAT REALLY CAUSED THIS PROB? THE FLC ON BOTH COMPANY ACFT HEARD THE CLRNC AND THOUGHT IT WAS MEANT FOR THEM. BOTH CREWS RESPONDED TO THE CLRNC AND ACKNOWLEDGED THE CLRNC BY READING IT BACK. THE PROB WAS CAUSED BY MISUNDERSTANDING THE CALL SIGN, POSSIBLY DUE TO RADIO INTERFERENCE, AND BY BOTH OF THE READBACKS OF THE CLRNC BEING XMITTED AT THE SAME TIME. WHAT CAN BE DONE TO PREVENT A RECURRENCE OR CORRECT THE SIT? OBVIOUSLY, ALL FLCS HAVE A RESPONSIBILITY TO DILIGENTLY LISTEN TO ALL RADIO CALLS AND RESPOND TO THEM APPROPRIATELY. HAVING 2 CREW MEMBERS IN EACH COCKPIT BOTH LISTENING TO THE SAME RADIO XMISSIONS SHOULD HELP TO REDUCE THE POSSIBILITY OF MISUNDERSTANDINGS INHERENT TO HUMAN SHORTCOMINGS, BUT OBVIOUSLY CANNOT PREVENT THEM ENTIRELY, AS EVIDENCED BY THIS SIT. FURTHERMORE, IF THE ATC CTLR NOTICED THAT 2 ACFT RESPONDED TO THE SAME CLRNC AT THE SAME TIME (AS APPARENTLY THE ZME PERSON REVIEWING THE TAPES DURING THE TELEPHONE CALL COULD HEAR THAT 2 ACFT XMITTED AT THE SAME TIME) AND HAD RE-EMPHASIZED THAT THE CLRNC IN QUESTION WAS MEANT ONLY FOR THE INTENDED ACFT, THEN WE WOULD NOT HAVE LEFT OUR ALT OF 16000 FT. WE FOUND OUT AFTERWARD THAT OUR COMPANY ACFT AHEAD NOTICED THAT ANOTHER XMISSION CONTINUED AFTER THEY UNKEYED THEIR XMITTER. HAD THEY QUESTIONED THIS OVER THE AIR, THEN WE COULD HAVE QUERIED ATC ABOUT OUR CLRNC. ANOTHER CONTRIBUTING FACTOR TO THIS SIT IS THAT ALL OF OUR COMPANY FLTS IN THE PART OF THE COUNTRY START WITH THE SAME DIGIT. IF WE HAD DIFFERING CALL SIGNS THEN THOSE DIFFERENCES WOULD BE MORE NOTICEABLE AND DISTINGUISHABLE DURING RADIO XMISSIONS. THE BEST FIX, HOWEVER, MAY COME WITH IMPROVED TECHNOLOGY. PERHAPS TECHNOLOGY THAT CAN IDENT TO ALL PARTIES CONCERNED THAT THEIR XMISSION WAS COVERED UP BY ANOTHER XMISSION, BY SENDING CLRNCS TO ACFT VIA TEXT UP-LINK, OR BY DESIGNING NEW RADIO TECHNOLOGY THAT ALLOWS AN ACFT'S RADIO TO RECEIVE ONLY THOSE ATC XMISSIONS THAT ARE SPECIFICALLY DIRECTLY AT THEM. ONE FINAL NOTE: MANY AIRMEN FILE NASA ASRS FORMS SOLELY TO TAKE ADVANTAGE OF THE IMMUNITY PROVISIONS. THIS AIRMAN HAS PLACED MUCH THOUGHT INTO FILLING OUT THE FORMS COMPLETELY AND ANSWERING THE FORM'S QUESTIONS THOUGHTFULLY WITH THE HOPE THAT SOME POSITIVE BENEFIT WILL RESULT.

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.