Narrative:

Approximately XA10 local, 40 NM east of gle at FL240, ZFW (134.15) cleared to descend to 4000 ft with 'a good rate.' I initiated descent at 3400 FPM. Approximately 1 min into descent, ZFW asks 'air carrier X how do you read center?' PNF responded 'loud and clear.' 20 seconds later, center transmits 'aircraft X if you read center, identify.' we idented and another aircraft transmitted that he heard us respond to the first center inquiry. Crew noticed a possible conflict on TCASII and was alert to the potential problem when center calls and says that we were 'last cleared to 16000 ft.' a clearance that we never received or acknowledged. Center told us to stop descent immediately, that we have traffic at 12 O'clock position and he stopped other aircraft's climb at 13000 ft as we leveled at 14000 ft. After passing traffic, we were reclred to 4000 ft. I believe this controller, after clearing us to 4000 ft, was alerted on another communications mode of conflicting traffic. He then tried to call us but had not switched to transmit on 134.15. When he finally did transmit on 134.15 he wasn't listening to 134.15 and could not hear our response. Either that or someone else blocked the controller's transmission and our xmissions back to him. This is unlikely since another aircraft said they heard us fine. Controllers are working too many aircraft. Frequency congestion is making it hard to communicate. Controllers are issuing clrncs that increase cockpit workload and contribute to confusion in the cockpit such as: aircraft in climb receives clearance 'you're cleared direct to mol after FL330.' in busy cockpit, that clearance provides for a chance of confusion. That clearance, and others like it, reduce the load on the overloaded controller but increase the load on the flight crew which can cause problems. Controllers increase the stress level and raise the potential for problems in the cockpit when they act as if the pilot messed up when the controller in fact messed up.

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Original NASA ASRS Text

Title: CPR TURBOJET PIC QUESTIONS ZFW'S COM WITH HIMSELF ABOUT OTHER POTENTIAL CONFLICTING TFC.

Narrative: APPROX XA10 LCL, 40 NM E OF GLE AT FL240, ZFW (134.15) CLRED TO DSND TO 4000 FT WITH 'A GOOD RATE.' I INITIATED DSCNT AT 3400 FPM. APPROX 1 MIN INTO DSCNT, ZFW ASKS 'ACR X HOW DO YOU READ CTR?' PNF RESPONDED 'LOUD AND CLR.' 20 SECONDS LATER, CTR XMITS 'ACFT X IF YOU READ CTR, IDENT.' WE IDENTED AND ANOTHER ACFT XMITTED THAT HE HEARD US RESPOND TO THE FIRST CTR INQUIRY. CREW NOTICED A POSSIBLE CONFLICT ON TCASII AND WAS ALERT TO THE POTENTIAL PROB WHEN CTR CALLS AND SAYS THAT WE WERE 'LAST CLRED TO 16000 FT.' A CLRNC THAT WE NEVER RECEIVED OR ACKNOWLEDGED. CTR TOLD US TO STOP DSCNT IMMEDIATELY, THAT WE HAVE TFC AT 12 O'CLOCK POS AND HE STOPPED OTHER ACFT'S CLB AT 13000 FT AS WE LEVELED AT 14000 FT. AFTER PASSING TFC, WE WERE RECLRED TO 4000 FT. I BELIEVE THIS CTLR, AFTER CLRING US TO 4000 FT, WAS ALERTED ON ANOTHER COMS MODE OF CONFLICTING TFC. HE THEN TRIED TO CALL US BUT HAD NOT SWITCHED TO XMIT ON 134.15. WHEN HE FINALLY DID XMIT ON 134.15 HE WASN'T LISTENING TO 134.15 AND COULD NOT HEAR OUR RESPONSE. EITHER THAT OR SOMEONE ELSE BLOCKED THE CTLR'S XMISSION AND OUR XMISSIONS BACK TO HIM. THIS IS UNLIKELY SINCE ANOTHER ACFT SAID THEY HEARD US FINE. CTLRS ARE WORKING TOO MANY ACFT. FREQ CONGESTION IS MAKING IT HARD TO COMMUNICATE. CTLRS ARE ISSUING CLRNCS THAT INCREASE COCKPIT WORKLOAD AND CONTRIBUTE TO CONFUSION IN THE COCKPIT SUCH AS: ACFT IN CLB RECEIVES CLRNC 'YOU'RE CLRED DIRECT TO MOL AFTER FL330.' IN BUSY COCKPIT, THAT CLRNC PROVIDES FOR A CHANCE OF CONFUSION. THAT CLRNC, AND OTHERS LIKE IT, REDUCE THE LOAD ON THE OVERLOADED CTLR BUT INCREASE THE LOAD ON THE FLC WHICH CAN CAUSE PROBS. CTLRS INCREASE THE STRESS LEVEL AND RAISE THE POTENTIAL FOR PROBS IN THE COCKPIT WHEN THEY ACT AS IF THE PLT MESSED UP WHEN THE CTLR IN FACT MESSED UP.

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.