Narrative:

I was PIC on air carrier X, operating bwi-roa on 3/X/91. WX was IFR with moderate rain, light to moderate turbulence, thunderstorms in the area. We were handed to roa approach control from ZDC. Approach issued a descent to 3800' on a southwest heading. ILS 33 was in use. Upon leveling at 3800', the aircraft GPWS issued terrain warnings. Unable to determine that the warning was invalid, we initiated a climb as per FAA approved training and fom procedure. At 4500' the warnings ceased and we leveled off. During the climb, the first officer alerted approach control of our climb and stated the reason as a GPWS warning. The controller asked if we could descend back to 3800'. The first officer responded negative and indicated our altitude of 4500'. The controller next gave us a traffic advisory. The controller finally issued a vector left to 180 degrees. After a brief period we were again vectored for the approach and landed west/O further problem. Supplemental information from acn 174276: after descending to 3800' MSL the GPWS issued a continuous aural and visibility 'terrain' alert. Since we could not immediately determine visually that we had adequate terrain clearance and the radar altimeter indicated decreasing ground clearance, we initiated a climb as required by the flight operations manual (4-25-4) and the pilot's operational handbook (18-25-1) to the published MSA (5300' MSL). After initiating the climb I notified roa approach that we had a GPWS alert and were climbing. The controller asked if we could descend to 3800' MSL. I replied, 'no,' that we had to climb to a higher altitude. The controller then gave us a traffic advisory. The GPWS stopped alerting at approximately 4500' MSL and the captain leveled the aircraft at that altitude. We had another brief communication with the controller who then assigned us an altitude and heading with which we complied. I feel that there was a serious error on the part of the air traffic controller in his failure to issue a climb clearance to us upon being notified that we had a GPWS alert. Roa has been designated by the FAA as a special airport due to mountainous terrain and high obstructions in the area. Because of the special nature of this airport, company has 9 pages of instructions to aid flight crews in arrival, approach and departure procedures. We operate into special airports with an increased level of awareness. Any deviation from normal indications in the aircraft require immediate action by the flight crew to prevent an accident. The controller however did not seem to be operating in such a mode. His delay in issuing climb clearance added to a sense of uncertainty in the cockpit as to what altitude we could safely climb to west/O creating a traffic conflict. I have 2 specific recommendations to make. First, flight crews are required to review the procedures at all on-line special airports in the route system on an annual basis. The controllers should be required to review the same information as the flight crews, as well as how the various warnings system operate, and the required flight crew actions. Second, when a controller has an aircraft operating below the MSA while on approach or departure from a special airport, south/he should keep the airspace above the aircraft protected so that in the event of an GPWS warning the captain can be assured of traffic sep up to and including the MSA.

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Original NASA ASRS Text

Title: ACR X NON ADHERENCE TO ATC CLRNC EXCURSION FROM ASSIGNED ALT DUE TO GPWS. PLT DEVIATION.

Narrative: I WAS PIC ON ACR X, OPERATING BWI-ROA ON 3/X/91. WX WAS IFR WITH MODERATE RAIN, LIGHT TO MODERATE TURB, TSTMS IN THE AREA. WE WERE HANDED TO ROA APCH CTL FROM ZDC. APCH ISSUED A DSNT TO 3800' ON A SW HDG. ILS 33 WAS IN USE. UPON LEVELING AT 3800', THE ACFT GPWS ISSUED TERRAIN WARNINGS. UNABLE TO DETERMINE THAT THE WARNING WAS INVALID, WE INITIATED A CLB AS PER FAA APPROVED TRNING AND FOM PROC. AT 4500' THE WARNINGS CEASED AND WE LEVELED OFF. DURING THE CLB, THE F/O ALERTED APCH CTL OF OUR CLB AND STATED THE REASON AS A GPWS WARNING. THE CTLR ASKED IF WE COULD DSND BACK TO 3800'. THE F/O RESPONDED NEGATIVE AND INDICATED OUR ALT OF 4500'. THE CTLR NEXT GAVE US A TFC ADVISORY. THE CTLR FINALLY ISSUED A VECTOR LEFT TO 180 DEGS. AFTER A BRIEF PERIOD WE WERE AGAIN VECTORED FOR THE APCH AND LANDED W/O FURTHER PROB. SUPPLEMENTAL INFO FROM ACN 174276: AFTER DSNDING TO 3800' MSL THE GPWS ISSUED A CONTINUOUS AURAL AND VIS 'TERRAIN' ALERT. SINCE WE COULD NOT IMMEDIATELY DETERMINE VISUALLY THAT WE HAD ADEQUATE TERRAIN CLRNC AND THE RADAR ALTIMETER INDICATED DECREASING GND CLRNC, WE INITIATED A CLB AS REQUIRED BY THE FLT OPS MANUAL (4-25-4) AND THE PLT'S OPERATIONAL HANDBOOK (18-25-1) TO THE PUBLISHED MSA (5300' MSL). AFTER INITIATING THE CLB I NOTIFIED ROA APCH THAT WE HAD A GPWS ALERT AND WERE CLBING. THE CTLR ASKED IF WE COULD DSND TO 3800' MSL. I REPLIED, 'NO,' THAT WE HAD TO CLB TO A HIGHER ALT. THE CTLR THEN GAVE US A TFC ADVISORY. THE GPWS STOPPED ALERTING AT APPROX 4500' MSL AND THE CAPT LEVELED THE ACFT AT THAT ALT. WE HAD ANOTHER BRIEF COM WITH THE CTLR WHO THEN ASSIGNED US AN ALT AND HDG WITH WHICH WE COMPLIED. I FEEL THAT THERE WAS A SERIOUS ERROR ON THE PART OF THE AIR TFC CTLR IN HIS FAILURE TO ISSUE A CLB CLRNC TO US UPON BEING NOTIFIED THAT WE HAD A GPWS ALERT. ROA HAS BEEN DESIGNATED BY THE FAA AS A SPECIAL ARPT DUE TO MOUNTAINOUS TERRAIN AND HIGH OBSTRUCTIONS IN THE AREA. BECAUSE OF THE SPECIAL NATURE OF THIS ARPT, COMPANY HAS 9 PAGES OF INSTRUCTIONS TO AID FLT CREWS IN ARR, APCH AND DEP PROCS. WE OPERATE INTO SPECIAL ARPTS WITH AN INCREASED LEVEL OF AWARENESS. ANY DEVIATION FROM NORMAL INDICATIONS IN THE ACFT REQUIRE IMMEDIATE ACTION BY THE FLT CREW TO PREVENT AN ACCIDENT. THE CTLR HOWEVER DID NOT SEEM TO BE OPERATING IN SUCH A MODE. HIS DELAY IN ISSUING CLB CLRNC ADDED TO A SENSE OF UNCERTAINTY IN THE COCKPIT AS TO WHAT ALT WE COULD SAFELY CLB TO W/O CREATING A TFC CONFLICT. I HAVE 2 SPECIFIC RECOMMENDATIONS TO MAKE. FIRST, FLT CREWS ARE REQUIRED TO REVIEW THE PROCS AT ALL ON-LINE SPECIAL ARPTS IN THE RTE SYS ON AN ANNUAL BASIS. THE CTLRS SHOULD BE REQUIRED TO REVIEW THE SAME INFO AS THE FLT CREWS, AS WELL AS HOW THE VARIOUS WARNINGS SYS OPERATE, AND THE REQUIRED FLT CREW ACTIONS. SECOND, WHEN A CTLR HAS AN ACFT OPERATING BELOW THE MSA WHILE ON APCH OR DEP FROM A SPECIAL ARPT, S/HE SHOULD KEEP THE AIRSPACE ABOVE THE ACFT PROTECTED SO THAT IN THE EVENT OF AN GPWS WARNING THE CAPT CAN BE ASSURED OF TFC SEP UP TO AND INCLUDING THE MSA.

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.