Narrative:

On a flight from norfolk, va, to boston, ma, I was captain in a learjet 25. We were given a climb from ATC (ZDC) from FL240 to FL280. Upon reaching, the controller told us, in an excited manner, to maintain FL270. We told him we were assigned FL280 but started a descent. He then said to expedite to FL290. At the same time we heard an air carrier pilot say something about 'he had us.' we assumed TCASII. So we expedited our climb to FL290. We were IMC and never saw the other aircraft. After the incident was over, my first officer, who I have flown with for 7 months, and I discussed the incident and are about 90% sure we both heard the instructions to climb to FL280. We both agreed that the controller seemed to be extremely busy at the time and perhaps over-saturated. It seems obvious that some human error caused this incident. The united states airspace is becoming increasingly over-saturated placing more responsibility on ATC controllers. From our point of view, we feel that if we had TCASII in our learjet 25 this incident may have been avoided. Supplemental information from acn 465763: while cruising at FL280, received a TA from TCASII of traffic 3 mi ahead, 100 ft below. 3 seconds later received RA monitor vertical speed (don't climb). Then, 1 or 2 seconds later RA 'descend, descend' (audio message from TCASII indicating a descent more than 2000 FPM required). I immediately followed by pitching down aggressively while informing ZDC of the descent in response to the RA. Heard center say 'don't' descend, he is descending.' TCASII then responded to the lear's descent by reversing itself, ordering a 2500 FPM climb saying, 'climb, climb now.' I aggressively pitched back up while noticing traffic on TCASII 1/4 mi at our same altitude (27600 ft and starting to climb). We climbed to 28300 ft when the TCASII warning ceased. The whole encounter lasted approximately 10 seconds. Luckily, all passenger and crew were belted in due to prior turbulence. Otherwise, there would have been many injuries due to the aggressive commands of the TCASII. Upon landing at destination called supervisor ZDC who said the lear was assigned FL270 but read back FL280 which the controller did not catch. He said the 'tapes' confirmed this and is being logged as an 'operational error' on their part. This is what can happen when you have flight levels only 1000 ft apart combined with a high performance jet, like a lear, that can cover 1000 ft in a climb within 10 seconds. Also, a controller should never have to work 2 frequencys at the same time. I believe that greater attention to just 1 frequency would eliminate many controller 'hearback' errors such as this one.

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Original NASA ASRS Text

Title: LOSS OF ACFT SEPARATION.

Narrative: ON A FLT FROM NORFOLK, VA, TO BOSTON, MA, I WAS CAPT IN A LEARJET 25. WE WERE GIVEN A CLB FROM ATC (ZDC) FROM FL240 TO FL280. UPON REACHING, THE CTLR TOLD US, IN AN EXCITED MANNER, TO MAINTAIN FL270. WE TOLD HIM WE WERE ASSIGNED FL280 BUT STARTED A DSCNT. HE THEN SAID TO EXPEDITE TO FL290. AT THE SAME TIME WE HEARD AN ACR PLT SAY SOMETHING ABOUT 'HE HAD US.' WE ASSUMED TCASII. SO WE EXPEDITED OUR CLB TO FL290. WE WERE IMC AND NEVER SAW THE OTHER ACFT. AFTER THE INCIDENT WAS OVER, MY FO, WHO I HAVE FLOWN WITH FOR 7 MONTHS, AND I DISCUSSED THE INCIDENT AND ARE ABOUT 90% SURE WE BOTH HEARD THE INSTRUCTIONS TO CLB TO FL280. WE BOTH AGREED THAT THE CTLR SEEMED TO BE EXTREMELY BUSY AT THE TIME AND PERHAPS OVER-SATURATED. IT SEEMS OBVIOUS THAT SOME HUMAN ERROR CAUSED THIS INCIDENT. THE UNITED STATES AIRSPACE IS BECOMING INCREASINGLY OVER-SATURATED PLACING MORE RESPONSIBILITY ON ATC CTLRS. FROM OUR POINT OF VIEW, WE FEEL THAT IF WE HAD TCASII IN OUR LEARJET 25 THIS INCIDENT MAY HAVE BEEN AVOIDED. SUPPLEMENTAL INFO FROM ACN 465763: WHILE CRUISING AT FL280, RECEIVED A TA FROM TCASII OF TFC 3 MI AHEAD, 100 FT BELOW. 3 SECONDS LATER RECEIVED RA MONITOR VERT SPD (DON'T CLB). THEN, 1 OR 2 SECONDS LATER RA 'DSND, DSND' (AUDIO MESSAGE FROM TCASII INDICATING A DSCNT MORE THAN 2000 FPM REQUIRED). I IMMEDIATELY FOLLOWED BY PITCHING DOWN AGGRESSIVELY WHILE INFORMING ZDC OF THE DSCNT IN RESPONSE TO THE RA. HEARD CTR SAY 'DON'T' DSND, HE IS DSNDING.' TCASII THEN RESPONDED TO THE LEAR'S DSCNT BY REVERSING ITSELF, ORDERING A 2500 FPM CLB SAYING, 'CLB, CLB NOW.' I AGGRESSIVELY PITCHED BACK UP WHILE NOTICING TFC ON TCASII 1/4 MI AT OUR SAME ALT (27600 FT AND STARTING TO CLB). WE CLBED TO 28300 FT WHEN THE TCASII WARNING CEASED. THE WHOLE ENCOUNTER LASTED APPROX 10 SECONDS. LUCKILY, ALL PAX AND CREW WERE BELTED IN DUE TO PRIOR TURB. OTHERWISE, THERE WOULD HAVE BEEN MANY INJURIES DUE TO THE AGGRESSIVE COMMANDS OF THE TCASII. UPON LNDG AT DEST CALLED SUPVR ZDC WHO SAID THE LEAR WAS ASSIGNED FL270 BUT READ BACK FL280 WHICH THE CTLR DID NOT CATCH. HE SAID THE 'TAPES' CONFIRMED THIS AND IS BEING LOGGED AS AN 'OPERROR' ON THEIR PART. THIS IS WHAT CAN HAPPEN WHEN YOU HAVE FLT LEVELS ONLY 1000 FT APART COMBINED WITH A HIGH PERFORMANCE JET, LIKE A LEAR, THAT CAN COVER 1000 FT IN A CLB WITHIN 10 SECONDS. ALSO, A CTLR SHOULD NEVER HAVE TO WORK 2 FREQS AT THE SAME TIME. I BELIEVE THAT GREATER ATTN TO JUST 1 FREQ WOULD ELIMINATE MANY CTLR 'HEARBACK' ERRORS SUCH AS THIS ONE.

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.