Narrative:

Air carrier X en route to san diego a FL350 was shipped to the next controller but read back in incorrect frequency. The pilots failed to recognize that they were on a frequency that center did not use. At the same time, an air carrier Y was shipped from albuquerque center to la center. The controller did not receive a read back acknowledging the frequency change. The la controllers realized early that these 2 aircraft, over 100 mi apart, were on a collision course. The controllers tried everything they could think of to reach the aircraft. They tried commercial radio, but that was not going to work on time and never did reach the aircraft. The controllers went back to the previous controllers and had them try and raise the aircraft, that failed. The next choice was to have another aircraft to try and reach the pilots on company frequency without success. The controllers went for VOR voice and that again failed. The last hope was that the aircraft had TCASII or they would miss each other. Luck is exactly the reason these 2 aircraft did not hit. They passed each other less than 3 mi apart at FL350. Neither aircraft saw each other, but they might have if I had been closer. NORDO aircraft are a common occurrence throughout the ATC system. The only aircraft we can raise routinely in a NORDO situation are military aircraft because they are required to monitor guard frequency. I believe this situation and many others could be prevented if commercial aircraft were required to monitor guard or to monitor a common frequency. The situation I described does not happen often but once in a lifetime is too much. Supplemental information from acn 190578. Air carrier X on a flight from 'den' to 'san'. I was operating the radio. I had received a frequency change from lax center. I read back 133.02, however the correct frequency was 133.20. After the change, I was distraction by a discussion relating to the instrument approach into 'san'. Approximately 5 min transpired when I realized I had not made contact with center. I called and had no response. I went back to the last frequency and was not able to make contact. I then started to try different frequencys that were listed on high altitude en route chart. During my search we were 'sel' called by arinc. They gave us the new frequency of 133.20. I called center and made contact. They told us to call them on the landline because of a loss of separation with air carrier Y over needles, ca. Apparently they did not have radio contact with him either. We had passed each other at the same altitude within 3.9 NM. The copilot had observed him as he passed in front of us. He wanted to question center about the 'closeness' of the other aircraft, however, I was in the process of finding a working frequency. TCASII would have been a big help in this situation. I also believe that the prospect of 2 aircraft crossing the same 'fix' at the same 'altitude' should have warranted an altitude change at the last frequency change just in case of this problem occurring. Supplemental information from acn 192190. Talking with lax center. Since we were approaching san (about 40 mins out), I was reviewing the arrival and discussing the approach plate with the captain (per company policy). During this discussion a frequency change ensued. Apparently the frequency was read back incorrectly. As the captain researched a frequency from the high altitude chart face, I observed aircraft position/navigation lights passing ahead of us from left to right. No deviation was required since we were passing well clear and behind the lights ahead. Shortly thereafter our SELCAL chimed. We responded and arinc directed us to lax center. Affecting this situation were the following factors: no TCASII was installed on this particular aircraft (yet). It would have advised us of the pending traffic alert. I should have been paying more attention to the frequency change while still reviewing the arrival and let down plates. Controller should have challenged our improper frequency readback. Old radio in aircraft was a single head dial up frequency type. A dual head (frequency swapping head) would have facilitated immediate return to old frequency. Generic sector radio frequencys for each navigation station. Printed on our flight plan would have been very helpful. 2, sometimes 3 callups to a new frequency controller (center-en route) are rapidly becoming the norm. 'On-a-land-line' or 'giving-a-briefing' are the usual responses. Simultaneous frequency use is a real problem when we can't (for what ever reason) hear the controller talking on the other frequency. Supplemental information from acn 191134. Air carrier Y was operating at FL350. Destination was lax and time to begin descent for the airport. All radio communication was normal. Air carrier Y requested descent at the appropriate time. Radio communication was a little busy, just prior to our request for descent. When our request was made to abq center we were told to contact lax center from frequency 135.15 to 133.2. The communication was loud and clear the entire time with abq center. Just before the switch, it sounded like abq center had handed off air carrier Y late. This switching was about 130 mi from lax.

Related reports:

Google
 

Original NASA ASRS Text

Title: ACR X FLC TECHNIQUE COM CHANGED TO WRONG FREQ. ACR Y DID NOT CHANGE FREQ AS INSTRUCTED. RADAR CTLR TECHNIQUE COM FAILED TO HEAR ACR X INCORRECT READBACK ALSO FAILED TO GET ACKNOWLEDGMENT OF FREQ CHANGE FROM ACR Y. ACR X HAD LTSS FROM ACR Y.

Narrative: ACR X ENRTE TO SAN DIEGO A FL350 WAS SHIPPED TO THE NEXT CTLR BUT READ BACK IN INCORRECT FREQ. THE PLTS FAILED TO RECOGNIZE THAT THEY WERE ON A FREQ THAT CENTER DID NOT USE. AT THE SAME TIME, AN ACR Y WAS SHIPPED FROM ALBUQUERQUE CENTER TO LA CENTER. THE CTLR DID NOT RECEIVE A READ BACK ACKNOWLEDGING THE FREQ CHANGE. THE LA CTLRS REALIZED EARLY THAT THESE 2 ACFT, OVER 100 MI APART, WERE ON A COLLISION COURSE. THE CTLRS TRIED EVERYTHING THEY COULD THINK OF TO REACH THE ACFT. THEY TRIED COMMERCIAL RADIO, BUT THAT WAS NOT GOING TO WORK ON TIME AND NEVER DID REACH THE ACFT. THE CTLRS WENT BACK TO THE PREVIOUS CTLRS AND HAD THEM TRY AND RAISE THE ACFT, THAT FAILED. THE NEXT CHOICE WAS TO HAVE ANOTHER ACFT TO TRY AND REACH THE PLTS ON COMPANY FREQ WITHOUT SUCCESS. THE CTLRS WENT FOR VOR VOICE AND THAT AGAIN FAILED. THE LAST HOPE WAS THAT THE ACFT HAD TCASII OR THEY WOULD MISS EACH OTHER. LUCK IS EXACTLY THE REASON THESE 2 ACFT DID NOT HIT. THEY PASSED EACH OTHER LESS THAN 3 MI APART AT FL350. NEITHER ACFT SAW EACH OTHER, BUT THEY MIGHT HAVE IF I HAD BEEN CLOSER. NORDO ACFT ARE A COMMON OCCURRENCE THROUGHOUT THE ATC SYS. THE ONLY ACFT WE CAN RAISE ROUTINELY IN A NORDO SITUATION ARE MIL ACFT BECAUSE THEY ARE REQUIRED TO MONITOR GUARD FREQ. I BELIEVE THIS SITUATION AND MANY OTHERS COULD BE PREVENTED IF COMMERCIAL ACFT WERE REQUIRED TO MONITOR GUARD OR TO MONITOR A COMMON FREQ. THE SITUATION I DESCRIBED DOES NOT HAPPEN OFTEN BUT ONCE IN A LIFETIME IS TOO MUCH. SUPPLEMENTAL INFO FROM ACN 190578. ACR X ON A FLT FROM 'DEN' TO 'SAN'. I WAS OPERATING THE RADIO. I HAD RECEIVED A FREQ CHANGE FROM LAX CENTER. I READ BACK 133.02, HOWEVER THE CORRECT FREQ WAS 133.20. AFTER THE CHANGE, I WAS DISTR BY A DISCUSSION RELATING TO THE INST APCH INTO 'SAN'. APPROX 5 MIN TRANSPIRED WHEN I REALIZED I HAD NOT MADE CONTACT WITH CENTER. I CALLED AND HAD NO RESPONSE. I WENT BACK TO THE LAST FREQ AND WAS NOT ABLE TO MAKE CONTACT. I THEN STARTED TO TRY DIFFERENT FREQS THAT WERE LISTED ON HIGH ALT ENRTE CHART. DURING MY SEARCH WE WERE 'SEL' CALLED BY ARINC. THEY GAVE US THE NEW FREQ OF 133.20. I CALLED CENTER AND MADE CONTACT. THEY TOLD US TO CALL THEM ON THE LANDLINE BECAUSE OF A LOSS OF SEPARATION WITH ACR Y OVER NEEDLES, CA. APPARENTLY THEY DID NOT HAVE RADIO CONTACT WITH HIM EITHER. WE HAD PASSED EACH OTHER AT THE SAME ALT WITHIN 3.9 NM. THE COPLT HAD OBSERVED HIM AS HE PASSED IN FRONT OF US. HE WANTED TO QUESTION CENTER ABOUT THE 'CLOSENESS' OF THE OTHER ACFT, HOWEVER, I WAS IN THE PROCESS OF FINDING A WORKING FREQ. TCASII WOULD HAVE BEEN A BIG HELP IN THIS SITUATION. I ALSO BELIEVE THAT THE PROSPECT OF 2 ACFT XING THE SAME 'FIX' AT THE SAME 'ALT' SHOULD HAVE WARRANTED AN ALT CHANGE AT THE LAST FREQ CHANGE JUST IN CASE OF THIS PROBLEM OCCURRING. SUPPLEMENTAL INFO FROM ACN 192190. TALKING WITH LAX CENTER. SINCE WE WERE APCHING SAN (ABOUT 40 MINS OUT), I WAS REVIEWING THE ARR AND DISCUSSING THE APCH PLATE WITH THE CAPT (PER COMPANY POLICY). DURING THIS DISCUSSION A FREQ CHANGE ENSUED. APPARENTLY THE FREQ WAS READ BACK INCORRECTLY. AS THE CAPT RESEARCHED A FREQ FROM THE HIGH ALT CHART FACE, I OBSERVED ACFT POS/NAV LIGHTS PASSING AHEAD OF US FROM L TO R. NO DEV WAS REQUIRED SINCE WE WERE PASSING WELL CLR AND BEHIND THE LIGHTS AHEAD. SHORTLY THEREAFTER OUR SELCAL CHIMED. WE RESPONDED AND ARINC DIRECTED US TO LAX CENTER. AFFECTING THIS SITUATION WERE THE FOLLOWING FACTORS: NO TCASII WAS INSTALLED ON THIS PARTICULAR ACFT (YET). IT WOULD HAVE ADVISED US OF THE PENDING TFC ALERT. I SHOULD HAVE BEEN PAYING MORE ATTN TO THE FREQ CHANGE WHILE STILL REVIEWING THE ARR AND LET DOWN PLATES. CTLR SHOULD HAVE CHALLENGED OUR IMPROPER FREQ READBACK. OLD RADIO IN ACFT WAS A SINGLE HEAD DIAL UP FREQ TYPE. A DUAL HEAD (FREQ SWAPPING HEAD) WOULD HAVE FACILITATED IMMEDIATE RETURN TO OLD FREQ. GENERIC SECTOR RADIO FREQS FOR EACH NAV STATION. PRINTED ON OUR FLT PLAN WOULD HAVE BEEN VERY HELPFUL. 2, SOMETIMES 3 CALLUPS TO A NEW FREQ CTLR (CENTER-ENRTE) ARE RAPIDLY BECOMING THE NORM. 'ON-A-LAND-LINE' OR 'GIVING-A-BRIEFING' ARE THE USUAL RESPONSES. SIMULTANEOUS FREQ USE IS A REAL PROBLEM WHEN WE CAN'T (FOR WHAT EVER REASON) HEAR THE CTLR TALKING ON THE OTHER FREQ. SUPPLEMENTAL INFO FROM ACN 191134. ACR Y WAS OPERATING AT FL350. DEST WAS LAX AND TIME TO BEGIN DSCNT FOR THE ARPT. ALL RADIO COM WAS NORMAL. ACR Y REQUESTED DSCNT AT THE APPROPRIATE TIME. RADIO COM WAS A LITTLE BUSY, JUST PRIOR TO OUR REQUEST FOR DSCNT. WHEN OUR REQUEST WAS MADE TO ABQ CENTER WE WERE TOLD TO CONTACT LAX CENTER FROM FREQ 135.15 TO 133.2. THE COM WAS LOUD AND CLR THE ENTIRE TIME WITH ABQ CENTER. JUST BEFORE THE SWITCH, IT SOUNDED LIKE ABQ CENTER HAD HANDED OFF ACR Y LATE. THIS SWITCHING WAS ABOUT 130 MI FROM LAX.

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.