Narrative:

Switched from tys tower to knoxville departure (123.9) around 2000 ft MSL. Departure assigned a turn to a nwesterly heading then to a northerly heading and assigned 10000 ft altitude. Passing approximately 8500 ft MSL received: master warning, GPWS: whoop, whoop, whoop, whoop, pull up, pull up, terrain, terrain, too low terrain, these warnings repeated multiple times. Brief communication between flight crew, PIC initiated CFIT escape maneuver per airline fsm xa-xx. GPWS warnings continued. PIC directed sic (PNF) to verify safe altitude. Sic requested safe altitude from knoxville departure, initial contact/request elicited vague response from ATC, our request may not have been clear as to the intent or reason for request. Second request for MVA evoked ATC to state '2500 ft.' PIC had continued CFIT escape procedure as warnings continued, it was night IMC and MSA is 8800 ft. Airline fsm directs CFIT escape maneuver to be enacted unless clear/VFR and flight crew immediately and unequivocally confirm that an impact with the ground/water/obstacle will not take place. Crew received 'MVA 2500' response at approximately 10000 ft MSL. Receiving this information and confirming lateral position, crew had assurance of terrain clearance, however warnings continued during leveloff at 10600 ft. When a descent was initiated to 10000 ft only then did warnings cease. ATC had also assigned a frequency change to ZTL during the situation. First officer had tried to make an attempt to contact ZTL without success, returned to knoxville approach/departure. The controller directed us to return to ZTL on same frequency, stated: 'you were 600 ft over your assigned altitude, we'll have to do something about that.' he told us to standby, then returned and simply directed us to the ZTL frequency. Upon reaching cvg, maintenance was notified, and aircraft was checked by airline's avionics technician/mechanic. Radar altimeter was determined to have multiple write-ups. Radar altimeter captain's side was subsequently deactivated per MEL, aircraft was cleared for continued flight. (Flight crew wrote up the problem in maintenance log.) flight departed cvg to mem, experienced identical circumstances and GPWS warnings at similar altitude, yet now in VMC conditions, daylight, MSA 2900 ft MSL, flight crew was able to immediately determine the aircraft was in a safe flight regime relative to terrain, therefore no CFIT escape maneuver was enacted. Contact was established with airline maintenance/avionics, we determined flight was safe and legal to continue to mem.

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Original NASA ASRS Text

Title: A CL65 FLC CLBS 600 FT ABOVE THEIR ASSIGNED ALT DURING A GPWS WARNING ON AN IMC, NIGHT DEP FROM TYS, TN.

Narrative: SWITCHED FROM TYS TWR TO KNOXVILLE DEP (123.9) AROUND 2000 FT MSL. DEP ASSIGNED A TURN TO A NWESTERLY HEADING THEN TO A NORTHERLY HEADING AND ASSIGNED 10000 FT ALT. PASSING APPROX 8500 FT MSL RECEIVED: MASTER WARNING, GPWS: WHOOP, WHOOP, WHOOP, WHOOP, PULL UP, PULL UP, TERRAIN, TERRAIN, TOO LOW TERRAIN, THESE WARNINGS REPEATED MULTIPLE TIMES. BRIEF COM BTWN FLC, PIC INITIATED CFIT ESCAPE MANEUVER PER AIRLINE FSM XA-XX. GPWS WARNINGS CONTINUED. PIC DIRECTED SIC (PNF) TO VERIFY SAFE ALT. SIC REQUESTED SAFE ALT FROM KNOXVILLE DEP, INITIAL CONTACT/REQUEST ELICITED VAGUE RESPONSE FROM ATC, OUR REQUEST MAY NOT HAVE BEEN CLR AS TO THE INTENT OR REASON FOR REQUEST. SECOND REQUEST FOR MVA EVOKED ATC TO STATE '2500 FT.' PIC HAD CONTINUED CFIT ESCAPE PROC AS WARNINGS CONTINUED, IT WAS NIGHT IMC AND MSA IS 8800 FT. AIRLINE FSM DIRECTS CFIT ESCAPE MANEUVER TO BE ENACTED UNLESS CLR/VFR AND FLC IMMEDIATELY AND UNEQUIVOCALLY CONFIRM THAT AN IMPACT WITH THE GND/WATER/OBSTACLE WILL NOT TAKE PLACE. CREW RECEIVED 'MVA 2500' RESPONSE AT APPROX 10000 FT MSL. RECEIVING THIS INFO AND CONFIRMING LATERAL POS, CREW HAD ASSURANCE OF TERRAIN CLRNC, HOWEVER WARNINGS CONTINUED DURING LEVELOFF AT 10600 FT. WHEN A DSCNT WAS INITIATED TO 10000 FT ONLY THEN DID WARNINGS CEASE. ATC HAD ALSO ASSIGNED A FREQ CHANGE TO ZTL DURING THE SIT. FO HAD TRIED TO MAKE AN ATTEMPT TO CONTACT ZTL WITHOUT SUCCESS, RETURNED TO KNOXVILLE APCH/DEP. THE CTLR DIRECTED US TO RETURN TO ZTL ON SAME FREQ, STATED: 'YOU WERE 600 FT OVER YOUR ASSIGNED ALT, WE'LL HAVE TO DO SOMETHING ABOUT THAT.' HE TOLD US TO STANDBY, THEN RETURNED AND SIMPLY DIRECTED US TO THE ZTL FREQ. UPON REACHING CVG, MAINT WAS NOTIFIED, AND ACFT WAS CHKED BY AIRLINE'S AVIONICS TECHNICIAN/MECH. RADAR ALTIMETER WAS DETERMINED TO HAVE MULTIPLE WRITE-UPS. RADAR ALTIMETER CAPT'S SIDE WAS SUBSEQUENTLY DEACTIVATED PER MEL, ACFT WAS CLRED FOR CONTINUED FLT. (FLC WROTE UP THE PROB IN MAINT LOG.) FLT DEPARTED CVG TO MEM, EXPERIENCED IDENTICAL CIRCUMSTANCES AND GPWS WARNINGS AT SIMILAR ALT, YET NOW IN VMC CONDITIONS, DAYLIGHT, MSA 2900 FT MSL, FLC WAS ABLE TO IMMEDIATELY DETERMINE THE ACFT WAS IN A SAFE FLT REGIME RELATIVE TO TERRAIN, THEREFORE NO CFIT ESCAPE MANEUVER WAS ENACTED. CONTACT WAS ESTABLISHED WITH AIRLINE MAINT/AVIONICS, WE DETERMINED FLT WAS SAFE AND LEGAL TO CONTINUE TO MEM.

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.