Narrative:

I was flying, captain was on radios. Roa WX clear and 50 mi. Roa approach had cleared us to descend and maintain 5000 ft. We approached from northeast. Roa landing runway 6. As we passed approximately 7000 ft, approach verified we had the airport in sight and then cleared us for a visual approach to runway 6 (without altitude restr and without reference to any traffic). Approach control then switched us over to tower. Tower told us we were #3 for landing and that he would call our base leg. Captain and I discussed how best to extend downwind and position ourselves for final on runway 6. I flew in close to airport to remain at safe distance from mountains west of airport. Abeam airport, I flew heading approximately 250 degrees to fly down the valley, keeping the higher terrain safely off both sides of aircraft and allowing myself room to make the left base and turn to final. After abeam, I slowed aircraft to approximately 165 KIAS and continued a slow rate of descent below 5000 ft. I had lda (with GS) runway 6 tuned and idented and approach plate out for reference. As I continued descent below 5000 ft, I felt a lack of information and probably should have pressed harder for more information. I was not sure how far out I would have to go before turning final. I referenced the altitudes on final and the approach and found it showed 4500 ft to 9.3 DME on the lda, then allowed descent to 2800 ft. I continued to keep close watch on the proximity of the hills on either side of us. My plan was to level at 2800 ft if tower had not turned us in for landing. At about 5.5 NM (still downwind) tower cleared us to land. He did not call our base first as he said he would. At this point I was about 3200 ft MSL. I commented to captain that he had not told us to turn base. He said we're cleared to land, to just turn in and don't worry about it. Just as I began my base (which was in actuality a left 180 degree turn to final), at 3100 ft MSL, and not more than 20-30 seconds after he cleared us to land, tower came on and announced he had a low altitude alert on us and that minimum vectoring altitude where we were was 3600 ft. Captain responded that we had been cleared to land, that we needed to descend to do that, that we had good visual contact with all the surrounding terrain and that we were maintaining safe distance from the terrain. Up until the time we turned on final and descended to the runway, we had maintained a minimum of approximately 2000 ft radio altitude above all terrain. As I rolled out on final at 5 NM lda DME at 3100 ft, I was 2 full dots high on glide path. From the time I rolled out on final at 5 DME, I did not see nor hear any landing traffic ahead of us. I should have pressed for more information from controllers which was not willingly given. I should have paid more attention to TCASII for traffic location information (but TCASII traffic has a bad habit of appearing and disappearing from screen). But both of these controllers -- why did approach controller clear us for a visual approach without restr when we were going to have to extend downwind? Why didn't tower give us information regarding minimum vectoring altitude when he required us to extend downwind? I don't have the answers to those questions but you can be sure I will get the answers to my questions next time we're placed in an odd situation like this.

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Original NASA ASRS Text

Title: FLC OF AN MLG ACR ACFT WAS ADVISED OF LOW WARNING ALERT BY TWR WHEN STARTING TO TURN FINAL DURING A VISUAL APCH.

Narrative: I WAS FLYING, CAPT WAS ON RADIOS. ROA WX CLR AND 50 MI. ROA APCH HAD CLRED US TO DSND AND MAINTAIN 5000 FT. WE APCHED FROM NE. ROA LNDG RWY 6. AS WE PASSED APPROX 7000 FT, APCH VERIFIED WE HAD THE ARPT IN SIGHT AND THEN CLRED US FOR A VISUAL APCH TO RWY 6 (WITHOUT ALT RESTR AND WITHOUT REF TO ANY TFC). APCH CTL THEN SWITCHED US OVER TO TWR. TWR TOLD US WE WERE #3 FOR LNDG AND THAT HE WOULD CALL OUR BASE LEG. CAPT AND I DISCUSSED HOW BEST TO EXTEND DOWNWIND AND POS OURSELVES FOR FINAL ON RWY 6. I FLEW IN CLOSE TO ARPT TO REMAIN AT SAFE DISTANCE FROM MOUNTAINS W OF ARPT. ABEAM ARPT, I FLEW HDG APPROX 250 DEGS TO FLY DOWN THE VALLEY, KEEPING THE HIGHER TERRAIN SAFELY OFF BOTH SIDES OF ACFT AND ALLOWING MYSELF ROOM TO MAKE THE L BASE AND TURN TO FINAL. AFTER ABEAM, I SLOWED ACFT TO APPROX 165 KIAS AND CONTINUED A SLOW RATE OF DSCNT BELOW 5000 FT. I HAD LDA (WITH GS) RWY 6 TUNED AND IDENTED AND APCH PLATE OUT FOR REF. AS I CONTINUED DSCNT BELOW 5000 FT, I FELT A LACK OF INFO AND PROBABLY SHOULD HAVE PRESSED HARDER FOR MORE INFO. I WAS NOT SURE HOW FAR OUT I WOULD HAVE TO GO BEFORE TURNING FINAL. I REFED THE ALTS ON FINAL AND THE APCH AND FOUND IT SHOWED 4500 FT TO 9.3 DME ON THE LDA, THEN ALLOWED DSCNT TO 2800 FT. I CONTINUED TO KEEP CLOSE WATCH ON THE PROX OF THE HILLS ON EITHER SIDE OF US. MY PLAN WAS TO LEVEL AT 2800 FT IF TWR HAD NOT TURNED US IN FOR LNDG. AT ABOUT 5.5 NM (STILL DOWNWIND) TWR CLRED US TO LAND. HE DID NOT CALL OUR BASE FIRST AS HE SAID HE WOULD. AT THIS POINT I WAS ABOUT 3200 FT MSL. I COMMENTED TO CAPT THAT HE HAD NOT TOLD US TO TURN BASE. HE SAID WE'RE CLRED TO LAND, TO JUST TURN IN AND DON'T WORRY ABOUT IT. JUST AS I BEGAN MY BASE (WHICH WAS IN ACTUALITY A L 180 DEG TURN TO FINAL), AT 3100 FT MSL, AND NOT MORE THAN 20-30 SECONDS AFTER HE CLRED US TO LAND, TWR CAME ON AND ANNOUNCED HE HAD A LOW ALT ALERT ON US AND THAT MINIMUM VECTORING ALT WHERE WE WERE WAS 3600 FT. CAPT RESPONDED THAT WE HAD BEEN CLRED TO LAND, THAT WE NEEDED TO DSND TO DO THAT, THAT WE HAD GOOD VISUAL CONTACT WITH ALL THE SURROUNDING TERRAIN AND THAT WE WERE MAINTAINING SAFE DISTANCE FROM THE TERRAIN. UP UNTIL THE TIME WE TURNED ON FINAL AND DSNDED TO THE RWY, WE HAD MAINTAINED A MINIMUM OF APPROX 2000 FT RADIO ALT ABOVE ALL TERRAIN. AS I ROLLED OUT ON FINAL AT 5 NM LDA DME AT 3100 FT, I WAS 2 FULL DOTS HIGH ON GLIDE PATH. FROM THE TIME I ROLLED OUT ON FINAL AT 5 DME, I DID NOT SEE NOR HEAR ANY LNDG TFC AHEAD OF US. I SHOULD HAVE PRESSED FOR MORE INFO FROM CTLRS WHICH WAS NOT WILLINGLY GIVEN. I SHOULD HAVE PAID MORE ATTN TO TCASII FOR TFC LOCATION INFO (BUT TCASII TFC HAS A BAD HABIT OF APPEARING AND DISAPPEARING FROM SCREEN). BUT BOTH OF THESE CTLRS -- WHY DID APCH CTLR CLR US FOR A VISUAL APCH WITHOUT RESTR WHEN WE WERE GOING TO HAVE TO EXTEND DOWNWIND? WHY DIDN'T TWR GIVE US INFO REGARDING MINIMUM VECTORING ALT WHEN HE REQUIRED US TO EXTEND DOWNWIND? I DON'T HAVE THE ANSWERS TO THOSE QUESTIONS BUT YOU CAN BE SURE I WILL GET THE ANSWERS TO MY QUESTIONS NEXT TIME WE'RE PLACED IN AN ODD SIT LIKE THIS.

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.