Narrative:

While at cruise altitude of FL410 with the autoplt engaged, we were issued a descent by ZDC to 'descend to FL290 and expect clearance to cross swann intersection at FL240.' the PNF selected FL290 in the altitude selector while reading back the clearance to ATC. The FMS was set for crossing swann intersection at FL240. We began our descent and completed the descent checklist. Approximately 2 mins later, we were issued a clearance to 'cross swann intersection at FL240 and maintain 310 KTS or better when able.' FL240 was selected in the altitude selector, and was read back to ATC and verified. Due to a strong tailwind (approximately 90- 100 KTS) a high descent rate (3500 FPM or greater) was needed to meet the crossing restriction. Vertical speed mode of the autoplt was selected and the vertical path display was being followed. The autoplt entered the altitude capture mode and began to arrest the high rate of descent. Just prior to passing through FL250 for FL240, the '1000 ft to go' altitude warning horn sounded followed immediately by a TCASII 'traffic, traffic' aural warning. An amber TA appeared on the TCASII display. We noted the relative position and bearing on the display and attempted to visually acquire the traffic but to no avail. Within 4-5 seconds of the aural 'traffic, traffic' advisory, we received a TCASII RA of 'descend, descend' at which time the PF disconnected the autoplt and flew the aircraft as per the TCASII command on the vertical speed indicator. Very shortly thereafter (approximately 3-4 seconds) the TCASII RA became 'increase descent, increase descent' which was complied with by the PF manually flying the vsi into the green. Prior to descending through our assigned altitude of FL240, the PNF announced to ATC on the radio that our aircraft was responding to a TCASII RA. Below FL240, both the PF and the PNF sighted an air carrier Y, an medium large transport to the left of our aircraft at approximately 10 to 1030 O'clock position in a climbing left turn. The PNF again announced to ATC that 'we are responding to an RA.' we entered the clouds shortly thereafter. The RA ceased and we immediately leveled our aircraft off between approximately FL233 and FL234. We again attempted to make contact with air carrier Y, but to no avail. We now attempted to climb back to our assigned altitude of FL240. Immediately after commencing our climb, we were issued a TCASII RA 'reduce climb, reduce climb,' which we responded to by maintaining our altitude. The PNF then informed ATC of our responding to the RA and of our altitude deviation and the PNF inquired as to 'where is air carrier Y located?' the controller responded that 'he should be at FL230 and you should be at FL240.' again, the PNF reiterated to ATC that 'a TCASII RA had been issued and complied with.' we began our climb back to FL240, passing out of the clouds at approximately FL237. We never heard air carrier Y call ATC nor did we ever regain visual contact. ATC inquired if everything was 'ok on our aircraft,' to which we responded 'affirmative.' approximately 5 mins later, we were informed by ATC of a 'pilot deviation occurrence' and to call the ATC quality assurance office 'the following business day.' we continued to our destination without further incident.

Google
 

Original NASA ASRS Text

Title: A CPR JET DSNDING AT A FAST RATE REACTS TO A TCASII RA BY INCREASING DSCNT RATE RESULTING IN FLT BELOW ASSIGNED ALT AND CONFLICTING WITH CLBING TFC.

Narrative: WHILE AT CRUISE ALT OF FL410 WITH THE AUTOPLT ENGAGED, WE WERE ISSUED A DSCNT BY ZDC TO 'DSND TO FL290 AND EXPECT CLRNC TO CROSS SWANN INTXN AT FL240.' THE PNF SELECTED FL290 IN THE ALT SELECTOR WHILE READING BACK THE CLRNC TO ATC. THE FMS WAS SET FOR XING SWANN INTXN AT FL240. WE BEGAN OUR DSCNT AND COMPLETED THE DSCNT CHKLIST. APPROX 2 MINS LATER, WE WERE ISSUED A CLRNC TO 'CROSS SWANN INTXN AT FL240 AND MAINTAIN 310 KTS OR BETTER WHEN ABLE.' FL240 WAS SELECTED IN THE ALT SELECTOR, AND WAS READ BACK TO ATC AND VERIFIED. DUE TO A STRONG TAILWIND (APPROX 90- 100 KTS) A HIGH DSCNT RATE (3500 FPM OR GREATER) WAS NEEDED TO MEET THE XING RESTRICTION. VERT SPD MODE OF THE AUTOPLT WAS SELECTED AND THE VERT PATH DISPLAY WAS BEING FOLLOWED. THE AUTOPLT ENTERED THE ALT CAPTURE MODE AND BEGAN TO ARREST THE HIGH RATE OF DSCNT. JUST PRIOR TO PASSING THROUGH FL250 FOR FL240, THE '1000 FT TO GO' ALT WARNING HORN SOUNDED FOLLOWED IMMEDIATELY BY A TCASII 'TFC, TFC' AURAL WARNING. AN AMBER TA APPEARED ON THE TCASII DISPLAY. WE NOTED THE RELATIVE POS AND BEARING ON THE DISPLAY AND ATTEMPTED TO VISUALLY ACQUIRE THE TFC BUT TO NO AVAIL. WITHIN 4-5 SECONDS OF THE AURAL 'TFC, TFC' ADVISORY, WE RECEIVED A TCASII RA OF 'DSND, DSND' AT WHICH TIME THE PF DISCONNECTED THE AUTOPLT AND FLEW THE ACFT AS PER THE TCASII COMMAND ON THE VERT SPD INDICATOR. VERY SHORTLY THEREAFTER (APPROX 3-4 SECONDS) THE TCASII RA BECAME 'INCREASE DSCNT, INCREASE DSCNT' WHICH WAS COMPLIED WITH BY THE PF MANUALLY FLYING THE VSI INTO THE GREEN. PRIOR TO DSNDING THROUGH OUR ASSIGNED ALT OF FL240, THE PNF ANNOUNCED TO ATC ON THE RADIO THAT OUR ACFT WAS RESPONDING TO A TCASII RA. BELOW FL240, BOTH THE PF AND THE PNF SIGHTED AN ACR Y, AN MLG TO THE L OF OUR ACFT AT APPROX 10 TO 1030 O'CLOCK POS IN A CLBING L TURN. THE PNF AGAIN ANNOUNCED TO ATC THAT 'WE ARE RESPONDING TO AN RA.' WE ENTERED THE CLOUDS SHORTLY THEREAFTER. THE RA CEASED AND WE IMMEDIATELY LEVELED OUR ACFT OFF BTWN APPROX FL233 AND FL234. WE AGAIN ATTEMPTED TO MAKE CONTACT WITH ACR Y, BUT TO NO AVAIL. WE NOW ATTEMPTED TO CLB BACK TO OUR ASSIGNED ALT OF FL240. IMMEDIATELY AFTER COMMENCING OUR CLB, WE WERE ISSUED A TCASII RA 'REDUCE CLB, REDUCE CLB,' WHICH WE RESPONDED TO BY MAINTAINING OUR ALT. THE PNF THEN INFORMED ATC OF OUR RESPONDING TO THE RA AND OF OUR ALTDEV AND THE PNF INQUIRED AS TO 'WHERE IS ACR Y LOCATED?' THE CTLR RESPONDED THAT 'HE SHOULD BE AT FL230 AND YOU SHOULD BE AT FL240.' AGAIN, THE PNF REITERATED TO ATC THAT 'A TCASII RA HAD BEEN ISSUED AND COMPLIED WITH.' WE BEGAN OUR CLB BACK TO FL240, PASSING OUT OF THE CLOUDS AT APPROX FL237. WE NEVER HEARD ACR Y CALL ATC NOR DID WE EVER REGAIN VISUAL CONTACT. ATC INQUIRED IF EVERYTHING WAS 'OK ON OUR ACFT,' TO WHICH WE RESPONDED 'AFFIRMATIVE.' APPROX 5 MINS LATER, WE WERE INFORMED BY ATC OF A 'PLTDEV OCCURRENCE' AND TO CALL THE ATC QUALITY ASSURANCE OFFICE 'THE FOLLOWING BUSINESS DAY.' WE CONTINUED TO OUR DEST WITHOUT FURTHER INCIDENT.

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.