Narrative:

In a hawker 700 toward the completion of an far 135 charter flight to apa, we experienced a taws warning alert and I deviated from my assigned altitude to climb away from terrain. WX was IMC in light snow and reduced visibility. It was dark outside. I was PF while the first officer was PNF. We were using overhead speakers and mikes for communication after I made a decision to remove our headsets earlier in the flight because the first officer complained of being unable to hear me over the cockpit intercom system. We were also using communication #2 as our primary radio for ATC since communication #1 standby frequency had become impossible to read during nighttime operations due to a failure of the led display. Typically, communication #1 is used for ATC by our hawker crews. While on the assigned heading at 8000 ft and approximately 20-25 mi southeast of the airport, the first officer attempted to identify the localizer frequencys but was unable to gain reception from that position. He mistakenly turned the volume down on the #2 communication radio at some point while doing this. It should be noted that on some aircraft we operate the communication and navigation radios are in reversed position on the radio panel which occasionally creates some confusion. After descending to 8000 ft MSL, the first officer commented he could see some lights outside the right side of the aircraft and that we seemed low. I looked at the radar altimeter and pointed to the indicator reading approximately 1100 ft AGL. It then dropped below 1000 ft and we received a taws alert, 'terrain, pull up.' I immediately disengaged the autoplt and climbed aggressively to 9000 ft indicated altitude and asked the first officer to report the deviation to ATC. ATC did not respond after several attempts to contact them and I reached down to check the volume knob on the communication #2 panel and noted it had been inadvertently turned down. After turning it up, ATC communications were established and we were cleared to continue on that heading at 8500 ft. ATC advised us they had been attempting to contact us for 10 mins to climb us. It was actually only 3-4 mins but it seemed odd to me that ATC would clear us back up while on a vector to the final approach course, especially since the heading was not changed and it was a good vector for a base leg. To my knowledge, there was no traffic immediately above us at that time but the aircraft is not equipped with TCASII. Although I was well rested, I believe that fatigue may have been a factor since both crew members had been assigned to do a different trip that same day prior to this one but the company reassigned that flight to a different crew and notified me early enough that I could stay in bed for another couple hours and get extra sleep. The first officer, however, stated that he had flown a full day the previous day, had received less than a full night of sleep, and was up and about in preparation to report for the earlier flight before he was notified that we were not flying that trip. He did not take the opportunity to get additional rest at the time. By the end of the last segment of the trip described in this report, his actions were indicative of fatigue. Callback conversation with reporter revealed the following information: the reporter stated that they were being vectored for runway 35R ILS. The taws system was newly installed in that aircraft and a new feature for the crew. They were surprised also that the alert would happen out in that area. As an afterthought, they wondered why they were allowed to be vectored at 8000 ft so far from the localizer and below the MVA for that area.

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Original NASA ASRS Text

Title: AN HS125-700 ON A VECTOR TO APA RWY 35R AT 8000 FT RECEIVED A TAWS WARNING AND CLBED.

Narrative: IN A HAWKER 700 TOWARD THE COMPLETION OF AN FAR 135 CHARTER FLT TO APA, WE EXPERIENCED A TAWS WARNING ALERT AND I DEVIATED FROM MY ASSIGNED ALT TO CLB AWAY FROM TERRAIN. WX WAS IMC IN LIGHT SNOW AND REDUCED VISIBILITY. IT WAS DARK OUTSIDE. I WAS PF WHILE THE FO WAS PNF. WE WERE USING OVERHEAD SPEAKERS AND MIKES FOR COM AFTER I MADE A DECISION TO REMOVE OUR HEADSETS EARLIER IN THE FLT BECAUSE THE FO COMPLAINED OF BEING UNABLE TO HEAR ME OVER THE COCKPIT INTERCOM SYS. WE WERE ALSO USING COM #2 AS OUR PRIMARY RADIO FOR ATC SINCE COM #1 STANDBY FREQ HAD BECOME IMPOSSIBLE TO READ DURING NIGHTTIME OPS DUE TO A FAILURE OF THE LED DISPLAY. TYPICALLY, COM #1 IS USED FOR ATC BY OUR HAWKER CREWS. WHILE ON THE ASSIGNED HDG AT 8000 FT AND APPROX 20-25 MI SE OF THE ARPT, THE FO ATTEMPTED TO IDENT THE LOC FREQS BUT WAS UNABLE TO GAIN RECEPTION FROM THAT POS. HE MISTAKENLY TURNED THE VOLUME DOWN ON THE #2 COM RADIO AT SOME POINT WHILE DOING THIS. IT SHOULD BE NOTED THAT ON SOME ACFT WE OPERATE THE COM AND NAV RADIOS ARE IN REVERSED POS ON THE RADIO PANEL WHICH OCCASIONALLY CREATES SOME CONFUSION. AFTER DSNDING TO 8000 FT MSL, THE FO COMMENTED HE COULD SEE SOME LIGHTS OUTSIDE THE R SIDE OF THE ACFT AND THAT WE SEEMED LOW. I LOOKED AT THE RADAR ALTIMETER AND POINTED TO THE INDICATOR READING APPROX 1100 FT AGL. IT THEN DROPPED BELOW 1000 FT AND WE RECEIVED A TAWS ALERT, 'TERRAIN, PULL UP.' I IMMEDIATELY DISENGAGED THE AUTOPLT AND CLBED AGGRESSIVELY TO 9000 FT INDICATED ALT AND ASKED THE FO TO RPT THE DEV TO ATC. ATC DID NOT RESPOND AFTER SEVERAL ATTEMPTS TO CONTACT THEM AND I REACHED DOWN TO CHK THE VOLUME KNOB ON THE COM #2 PANEL AND NOTED IT HAD BEEN INADVERTENTLY TURNED DOWN. AFTER TURNING IT UP, ATC COMS WERE ESTABLISHED AND WE WERE CLRED TO CONTINUE ON THAT HDG AT 8500 FT. ATC ADVISED US THEY HAD BEEN ATTEMPTING TO CONTACT US FOR 10 MINS TO CLB US. IT WAS ACTUALLY ONLY 3-4 MINS BUT IT SEEMED ODD TO ME THAT ATC WOULD CLR US BACK UP WHILE ON A VECTOR TO THE FINAL APCH COURSE, ESPECIALLY SINCE THE HDG WAS NOT CHANGED AND IT WAS A GOOD VECTOR FOR A BASE LEG. TO MY KNOWLEDGE, THERE WAS NO TFC IMMEDIATELY ABOVE US AT THAT TIME BUT THE ACFT IS NOT EQUIPPED WITH TCASII. ALTHOUGH I WAS WELL RESTED, I BELIEVE THAT FATIGUE MAY HAVE BEEN A FACTOR SINCE BOTH CREW MEMBERS HAD BEEN ASSIGNED TO DO A DIFFERENT TRIP THAT SAME DAY PRIOR TO THIS ONE BUT THE COMPANY REASSIGNED THAT FLT TO A DIFFERENT CREW AND NOTIFIED ME EARLY ENOUGH THAT I COULD STAY IN BED FOR ANOTHER COUPLE HRS AND GET EXTRA SLEEP. THE FO, HOWEVER, STATED THAT HE HAD FLOWN A FULL DAY THE PREVIOUS DAY, HAD RECEIVED LESS THAN A FULL NIGHT OF SLEEP, AND WAS UP AND ABOUT IN PREPARATION TO RPT FOR THE EARLIER FLT BEFORE HE WAS NOTIFIED THAT WE WERE NOT FLYING THAT TRIP. HE DID NOT TAKE THE OPPORTUNITY TO GET ADDITIONAL REST AT THE TIME. BY THE END OF THE LAST SEGMENT OF THE TRIP DESCRIBED IN THIS RPT, HIS ACTIONS WERE INDICATIVE OF FATIGUE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THAT THEY WERE BEING VECTORED FOR RWY 35R ILS. THE TAWS SYS WAS NEWLY INSTALLED IN THAT ACFT AND A NEW FEATURE FOR THE CREW. THEY WERE SURPRISED ALSO THAT THE ALERT WOULD HAPPEN OUT IN THAT AREA. AS AN AFTERTHOUGHT, THEY WONDERED WHY THEY WERE ALLOWED TO BE VECTORED AT 8000 FT SO FAR FROM THE LOC AND BELOW THE MVA FOR THAT AREA.

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.