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BE36 pilot has throttle vernier problems and descends below assigned altitude while conducting an approach to vgt under L30 control.
| Attributes | |
| ACN | 510172 |
| Time | |
| Date | 200105 |
| Day | Wed |
| Place | |
| Locale Reference | airport : las.airport |
| State Reference | NV |
| Altitude | msl single value : 6000 |
| Environment | |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : l30.tracon |
| Operator | general aviation : corporate |
| Make Model Name | Bonanza 36 |
| Operating Under FAR Part | Part 91 |
| Route In Use | approach : visual |
| Flight Plan | IFR |
| Aircraft 2 | |
| Controlling Facilities | tracon : l30.tracon |
| Operator | common carrier : air carrier |
| Make Model Name | B767 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | climbout : initial |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : corporate |
| Function | flight crew : single pilot |
| Experience | flight time last 90 days : 45 flight time total : 4012 flight time type : 2450 |
| ASRS Report | 510172 |
| Person 2 | |
| Affiliation | government : faa |
| Function | controller : approach |
| Events | |
| Anomaly | aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly |
| Independent Detector | atc equipment other atc equipment : radar other controllera |
| Resolutory Action | controller : issued advisory controller : issued new clearance flight crew : became reoriented flight crew : took precautionary avoidance action flight crew : landed in emergency condition flight crew : returned to assigned altitude |
| Consequence | faa : reviewed incident with flight crew |
| Supplementary | |
| Problem Areas | Aircraft Flight Crew Human Performance |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
I was on an IFR flight plan from el paso international. I was given a vector to fly heading 270 degrees at 6000 ft. This vector took me just south of the southern boundary of mccarran field. When I first called approach southeast of mccarran, they said I was garbled. I repeated my transmission and they acknowledged. I responded to the vector and altitude. A short time later, approach said 'I need you to acknowledge my xmissions.' this puzzled me, since I had heard none. I acknowledged this. I was then told about traffic at 2 O'clock position, climbing, a B767 (I was on heading 270 degrees). I looked and said 'looking.' I did not see the traffic. I kept looking. Then I heard conversation from someone (I am not sure who) said 'we got an RA.' I do not know who this came from. Not sure if it was the B767 or someone else. At any rate, there was some conversation about the RA between ATC and some aircraft. Then I was told to turn to 360 degree heading and expect visual approach to runway 30 at north las vegas. I acknowledged. I turned and began to throttle back for descent (I was at 6000 ft and field elevation was about 2200 ft. I was 5-6 mi south). At that point my throttle vernier retention screw unthreaded, popping the spring-loaded vernier control. The throttle moved to full power, and I had to maintain tension by holding the throttle and pulling back (could not let it go, as it moved quickly to full power). I had to use one hand to keep the throttle retarded, switching back and forth to use the controls, put flaps down to approach, and to lower the gear (was high close in). Between distraction and commotion, I did allow a descent to begin. Things stabilized (gear down and approach flaps, throttle steady with hand tension), and I asked approach control 'please confirm my altitude restr.' the voice said 'you were not cleared for the visual approach, only to expect the visual approach.' I said 'roger' and began a climb from about 5400 ft back to 6000 ft. I had climbed about 100-200 ft and another voice came on and said 'you are cleared for the visual approach to runway 30 north las vegas.' I said 'roger.' that same person then told me to stay on a northerly heading (I was going too far east) as I made the approach. I landed uneventfully, having to hold the throttle retarded until shutdown. I parked at the FBO. I asked the person who parked me for a phillips screwdriver, found the vernier cap, spring, and screw and repaired the throttle cable. In retrospect, I was chagrined by the announcement that I had a garbled transmission after hours and hours of no problem that day. I was chagrined when I was told 'I need to know if you are with me' (I am not sure of the exact words) when I was listening intently. I was concerned about the RA announcement and the commotion sorting it out and wondering if it was the B767 that I never saw. I was further compromised when at that moment the vernier let go. Nonetheless, I must acknowledge that I was indeed not given a clearance for visual approach. I know that 'expect visual approach' does not mean 'cleared for visual approach.' in all the confusion between my doubts about approach hearing me, about the RA, and the throttle commotion, I indeed allowed a descent. Something did not seem right, which prompted me to ask about altitude confirmation when I was at about 5400 ft. That is when I ws told I had not been cleared. I should have done the following: asked if I was being received loud and clear. Asked if the RA pertained to me and the B767. Announced my throttle problem. Not descended below 6000 ft and then asked about confirmation, but stayed at 6000 ft until I knew. The commotion distraction me.
Original NASA ASRS Text
Title: BE36 PLT HAS THROTTLE VERNIER PROBS AND DSNDS BELOW ASSIGNED ALT WHILE CONDUCTING AN APCH TO VGT UNDER L30 CTL.
Narrative: I WAS ON AN IFR FLT PLAN FROM EL PASO INTL. I WAS GIVEN A VECTOR TO FLY HDG 270 DEGS AT 6000 FT. THIS VECTOR TOOK ME JUST S OF THE SOUTHERN BOUNDARY OF MCCARRAN FIELD. WHEN I FIRST CALLED APCH SE OF MCCARRAN, THEY SAID I WAS GARBLED. I REPEATED MY XMISSION AND THEY ACKNOWLEDGED. I RESPONDED TO THE VECTOR AND ALT. A SHORT TIME LATER, APCH SAID 'I NEED YOU TO ACKNOWLEDGE MY XMISSIONS.' THIS PUZZLED ME, SINCE I HAD HEARD NONE. I ACKNOWLEDGED THIS. I WAS THEN TOLD ABOUT TFC AT 2 O'CLOCK POS, CLBING, A B767 (I WAS ON HDG 270 DEGS). I LOOKED AND SAID 'LOOKING.' I DID NOT SEE THE TFC. I KEPT LOOKING. THEN I HEARD CONVERSATION FROM SOMEONE (I AM NOT SURE WHO) SAID 'WE GOT AN RA.' I DO NOT KNOW WHO THIS CAME FROM. NOT SURE IF IT WAS THE B767 OR SOMEONE ELSE. AT ANY RATE, THERE WAS SOME CONVERSATION ABOUT THE RA BTWN ATC AND SOME ACFT. THEN I WAS TOLD TO TURN TO 360 DEG HDG AND EXPECT VISUAL APCH TO RWY 30 AT NORTH LAS VEGAS. I ACKNOWLEDGED. I TURNED AND BEGAN TO THROTTLE BACK FOR DSCNT (I WAS AT 6000 FT AND FIELD ELEVATION WAS ABOUT 2200 FT. I WAS 5-6 MI S). AT THAT POINT MY THROTTLE VERNIER RETENTION SCREW UNTHREADED, POPPING THE SPRING-LOADED VERNIER CTL. THE THROTTLE MOVED TO FULL PWR, AND I HAD TO MAINTAIN TENSION BY HOLDING THE THROTTLE AND PULLING BACK (COULD NOT LET IT GO, AS IT MOVED QUICKLY TO FULL PWR). I HAD TO USE ONE HAND TO KEEP THE THROTTLE RETARDED, SWITCHING BACK AND FORTH TO USE THE CTLS, PUT FLAPS DOWN TO APCH, AND TO LOWER THE GEAR (WAS HIGH CLOSE IN). BTWN DISTR AND COMMOTION, I DID ALLOW A DSCNT TO BEGIN. THINGS STABILIZED (GEAR DOWN AND APCH FLAPS, THROTTLE STEADY WITH HAND TENSION), AND I ASKED APCH CTL 'PLEASE CONFIRM MY ALT RESTR.' THE VOICE SAID 'YOU WERE NOT CLRED FOR THE VISUAL APCH, ONLY TO EXPECT THE VISUAL APCH.' I SAID 'ROGER' AND BEGAN A CLB FROM ABOUT 5400 FT BACK TO 6000 FT. I HAD CLBED ABOUT 100-200 FT AND ANOTHER VOICE CAME ON AND SAID 'YOU ARE CLRED FOR THE VISUAL APCH TO RWY 30 NORTH LAS VEGAS.' I SAID 'ROGER.' THAT SAME PERSON THEN TOLD ME TO STAY ON A NORTHERLY HDG (I WAS GOING TOO FAR E) AS I MADE THE APCH. I LANDED UNEVENTFULLY, HAVING TO HOLD THE THROTTLE RETARDED UNTIL SHUTDOWN. I PARKED AT THE FBO. I ASKED THE PERSON WHO PARKED ME FOR A PHILLIPS SCREWDRIVER, FOUND THE VERNIER CAP, SPRING, AND SCREW AND REPAIRED THE THROTTLE CABLE. IN RETROSPECT, I WAS CHAGRINED BY THE ANNOUNCEMENT THAT I HAD A GARBLED XMISSION AFTER HRS AND HRS OF NO PROB THAT DAY. I WAS CHAGRINED WHEN I WAS TOLD 'I NEED TO KNOW IF YOU ARE WITH ME' (I AM NOT SURE OF THE EXACT WORDS) WHEN I WAS LISTENING INTENTLY. I WAS CONCERNED ABOUT THE RA ANNOUNCEMENT AND THE COMMOTION SORTING IT OUT AND WONDERING IF IT WAS THE B767 THAT I NEVER SAW. I WAS FURTHER COMPROMISED WHEN AT THAT MOMENT THE VERNIER LET GO. NONETHELESS, I MUST ACKNOWLEDGE THAT I WAS INDEED NOT GIVEN A CLRNC FOR VISUAL APCH. I KNOW THAT 'EXPECT VISUAL APCH' DOES NOT MEAN 'CLRED FOR VISUAL APCH.' IN ALL THE CONFUSION BTWN MY DOUBTS ABOUT APCH HEARING ME, ABOUT THE RA, AND THE THROTTLE COMMOTION, I INDEED ALLOWED A DSCNT. SOMETHING DID NOT SEEM RIGHT, WHICH PROMPTED ME TO ASK ABOUT ALT CONFIRMATION WHEN I WAS AT ABOUT 5400 FT. THAT IS WHEN I WS TOLD I HAD NOT BEEN CLRED. I SHOULD HAVE DONE THE FOLLOWING: ASKED IF I WAS BEING RECEIVED LOUD AND CLR. ASKED IF THE RA PERTAINED TO ME AND THE B767. ANNOUNCED MY THROTTLE PROB. NOT DSNDED BELOW 6000 FT AND THEN ASKED ABOUT CONFIRMATION, BUT STAYED AT 6000 FT UNTIL I KNEW. THE COMMOTION DISTR ME.
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.