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Military aircraft attempting to obtain IFR clearance from center had communication difficulty, intermittent and unable to confirm assigned altitude. Communication problem occurred more than once and reporter believes a blind spot in the vicinity of R-3202 is the cause. Altitude deviation resulted due to misunderstood clearance and unable to read back until after the deviation.
| Attributes | |
| ACN | 335500 |
| Time | |
| Date | 199605 |
| Day | Thu |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : muo |
| State Reference | ID |
| Altitude | msl bound lower : 16000 msl bound upper : 27000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zlc |
| Operator | other |
| Make Model Name | Intruder (A6) |
| Operating Under FAR Part | Part 91 |
| Flight Phase | climbout : intermediate altitude cruise other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | government : military |
| Function | flight crew : single pilot |
| Qualification | pilot : commercial pilot : military pilot : instrument |
| Experience | flight time last 90 days : 60 flight time total : 2200 flight time type : 1600 |
| ASRS Report | 335500 |
| Person 2 | |
| Affiliation | government : faa |
| Function | controller : radar |
| Qualification | controller : radar |
| Events | |
| Anomaly | altitude deviation : overshoot non adherence : clearance non adherence : far other anomaly other |
| Independent Detector | other flight crewa |
| Resolutory Action | none taken : detected after the fact |
| Consequence | Other |
| Supplementary | |
| Air Traffic Incident | Pilot Deviation |
| Situations | |
| ATC Facility | other physical facility |
Narrative:
After completing work in the mountain home airforce base electronic range (R-3202,a,B,C) we had a difficult time obtaining our IFR clearance to hill airforce base. The electronic range gave us a center frequency which we attempted several times with no luck. Eventually we got in contact with mountain home approach and tried to obtain clearance and a handoff to center from them. We were holding in the vicinity of the mountain home (mou) 146050. Approach gave us a vector of 320 degrees and an assigned altitude of 16000 ft. We descended from out VFR altitude of 16500 ft. Approach then asked what altitude we wanted for our flight to hill, we requested FL240. After approach got us heading east they switched us to ZLC where we were given a clearance, which included an altitude. It was difficult to understand center, but we believed we were assigned an altitude of FL270. During our climb we continuously tried contacting center to clarify our clearance. The next time we were able to communicate was when we were passing FL200. We called 'passing FL200 for FL270' and requested clarification of our clearance. Upon reaching FL270 we received a call on guard telling us our assigned altitude was actually 17000 ft. We offered to descend, but were told to remain where we were. On our second flight (same day) into R-3202 we noted it was once again difficult to maintain radio contact below FL190. I believed this happened due to a possible blind spot of salt lake city's radios in the vicinity of R-3202. The crew was also expecting an altitude of FL240 or FL250, so FL270 was in the vicinity of what was expected. 17000 ft was only 1000 ft above our current altitude and a climb of only 1000 ft wasn't anticipated. The combination of our anticipation of a higher altitude and less than optimum radio reception led to this misunderstanding.
Original NASA ASRS Text
Title: MIL ACFT ATTEMPTING TO OBTAIN IFR CLRNC FROM CTR HAD COM DIFFICULTY, INTERMITTENT AND UNABLE TO CONFIRM ASSIGNED ALT. COM PROB OCCURRED MORE THAN ONCE AND RPTR BELIEVES A BLIND SPOT IN THE VICINITY OF R-3202 IS THE CAUSE. ALTDEV RESULTED DUE TO MISUNDERSTOOD CLRNC AND UNABLE TO READ BACK UNTIL AFTER THE DEV.
Narrative: AFTER COMPLETING WORK IN THE MOUNTAIN HOME AIRFORCE BASE ELECTRONIC RANGE (R-3202,A,B,C) WE HAD A DIFFICULT TIME OBTAINING OUR IFR CLRNC TO HILL AIRFORCE BASE. THE ELECTRONIC RANGE GAVE US A CTR FREQ WHICH WE ATTEMPTED SEVERAL TIMES WITH NO LUCK. EVENTUALLY WE GOT IN CONTACT WITH MOUNTAIN HOME APCH AND TRIED TO OBTAIN CLRNC AND A HDOF TO CTR FROM THEM. WE WERE HOLDING IN THE VICINITY OF THE MOUNTAIN HOME (MOU) 146050. APCH GAVE US A VECTOR OF 320 DEGS AND AN ASSIGNED ALT OF 16000 FT. WE DSNDED FROM OUT VFR ALT OF 16500 FT. APCH THEN ASKED WHAT ALT WE WANTED FOR OUR FLT TO HILL, WE REQUESTED FL240. AFTER APCH GOT US HEADING E THEY SWITCHED US TO ZLC WHERE WE WERE GIVEN A CLRNC, WHICH INCLUDED AN ALT. IT WAS DIFFICULT TO UNDERSTAND CTR, BUT WE BELIEVED WE WERE ASSIGNED AN ALT OF FL270. DURING OUR CLB WE CONTINUOUSLY TRIED CONTACTING CTR TO CLARIFY OUR CLRNC. THE NEXT TIME WE WERE ABLE TO COMMUNICATE WAS WHEN WE WERE PASSING FL200. WE CALLED 'PASSING FL200 FOR FL270' AND REQUESTED CLARIFICATION OF OUR CLRNC. UPON REACHING FL270 WE RECEIVED A CALL ON GUARD TELLING US OUR ASSIGNED ALT WAS ACTUALLY 17000 FT. WE OFFERED TO DSND, BUT WERE TOLD TO REMAIN WHERE WE WERE. ON OUR SECOND FLT (SAME DAY) INTO R-3202 WE NOTED IT WAS ONCE AGAIN DIFFICULT TO MAINTAIN RADIO CONTACT BELOW FL190. I BELIEVED THIS HAPPENED DUE TO A POSSIBLE BLIND SPOT OF SALT LAKE CITY'S RADIOS IN THE VICINITY OF R-3202. THE CREW WAS ALSO EXPECTING AN ALT OF FL240 OR FL250, SO FL270 WAS IN THE VICINITY OF WHAT WAS EXPECTED. 17000 FT WAS ONLY 1000 FT ABOVE OUR CURRENT ALT AND A CLB OF ONLY 1000 FT WASN'T ANTICIPATED. THE COMBINATION OF OUR ANTICIPATION OF A HIGHER ALT AND LESS THAN OPTIMUM RADIO RECEPTION LED TO THIS MISUNDERSTANDING.
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.