Narrative:

On the ground at casper airport at casper, wy, I obtained a WX briefing and filed an IFR flight plan from casper airport (cpr) direct to centennial airport, denver, co (apa). No significant WX was expected along my planned route except some level 1 rain well south of casper. I received an IFR clearance from casper tower (cleared to apa via casper 1 departure then as filed, climb and maintain 11000 ft, departure frequency 120.65, squawk 5122). Mins after becoming airborne I began to monitor an area of building cumulus directly in my flight path that I estimated to be about 15 to 20 mi away. From live radar that I saw at the WX briefing within the last hour, I was surprised to see such activity so near casper. In addition, because of rising terrain south and southwest of casper, I was also monitoring my proximity to the ground. During this period when I was monitoring the building cumulus, my ground clearance, and watching for traffic I deviated from the runway heading of 210 degree (part of the casper 1 departure) by perhaps as much as 10 to 15 degree to the left. Casper tower made no comment about this deviation, however, upon switching the casper departure (approximately 3 to 4 mins after departure), I was immediately and curtly informed that my clearance was to fly runway heading and I was given a heading of 260 degree to fly. Within another 1 min I was asked if I could visually maintain ground clearance, I responded yes and was given a heading of 180 degree to fly. I had been in clear conditions since takeoff and would remain so for another several mins, however, the 180 degree heading would take me directly into a building cumulus with an estimated top of 25000 ft. After another few mins, I leveled at 11000 ft with cruise confign and asked to deviate to avoid the buildup. An exasperated sounding controller told me I could not deviate west but did ultimately give me a 100 degree heading. After a few mins the controller told me that if I could not fly in IMC he would have to rerte me to victor airways many mi to the east of my current routing because he said he would lose radar contact of me. At about the same time I accepted the new routing, I went into IMC with light to occasionally moderate turbulence. After transferring to denver center (135.6) a few mins later, I was given a 110 degree heading and 12000 ft to join victor 19 into cheyenne (cys). I encountered little turbulence and the remainder of the trip was uneventful. I attribute the above occurrence to 1) unexpected convective activity, 2) rising terrain, 3) good visual conditions requiring outside the cockpit scanning, 4) a controller concerned about terrain clearance who offered few options to avoid convective activity. Better management of heading while visually scanning outside the aircraft and perhaps better communication techniques so as to avoid aggravating the controller, would have prevented this occurrence.

Related reports:

Google
 

Original NASA ASRS Text

Title: PLT OF SMA DEPARTING CPR DEVIATED FROM CLRNC AND HDG. DEP CTLR INTERVENED AND RERTED PLT AROUND HVY WX.

Narrative: ON THE GND AT CASPER ARPT AT CASPER, WY, I OBTAINED A WX BRIEFING AND FILED AN IFR FLT PLAN FROM CASPER ARPT (CPR) DIRECT TO CENTENNIAL ARPT, DENVER, CO (APA). NO SIGNIFICANT WX WAS EXPECTED ALONG MY PLANNED RTE EXCEPT SOME LEVEL 1 RAIN WELL S OF CASPER. I RECEIVED AN IFR CLRNC FROM CASPER TWR (CLRED TO APA VIA CASPER 1 DEP THEN AS FILED, CLB AND MAINTAIN 11000 FT, DEP FREQ 120.65, SQUAWK 5122). MINS AFTER BECOMING AIRBORNE I BEGAN TO MONITOR AN AREA OF BUILDING CUMULUS DIRECTLY IN MY FLT PATH THAT I ESTIMATED TO BE ABOUT 15 TO 20 MI AWAY. FROM LIVE RADAR THAT I SAW AT THE WX BRIEFING WITHIN THE LAST HR, I WAS SURPRISED TO SEE SUCH ACTIVITY SO NEAR CASPER. IN ADDITION, BECAUSE OF RISING TERRAIN S AND SW OF CASPER, I WAS ALSO MONITORING MY PROX TO THE GND. DURING THIS PERIOD WHEN I WAS MONITORING THE BUILDING CUMULUS, MY GND CLRNC, AND WATCHING FOR TFC I DEVIATED FROM THE RWY HDG OF 210 DEG (PART OF THE CASPER 1 DEP) BY PERHAPS AS MUCH AS 10 TO 15 DEG TO THE L. CASPER TWR MADE NO COMMENT ABOUT THIS DEV, HOWEVER, UPON SWITCHING THE CASPER DEP (APPROX 3 TO 4 MINS AFTER DEP), I WAS IMMEDIATELY AND CURTLY INFORMED THAT MY CLRNC WAS TO FLY RWY HDG AND I WAS GIVEN A HDG OF 260 DEG TO FLY. WITHIN ANOTHER 1 MIN I WAS ASKED IF I COULD VISUALLY MAINTAIN GND CLRNC, I RESPONDED YES AND WAS GIVEN A HDG OF 180 DEG TO FLY. I HAD BEEN IN CLR CONDITIONS SINCE TKOF AND WOULD REMAIN SO FOR ANOTHER SEVERAL MINS, HOWEVER, THE 180 DEG HDG WOULD TAKE ME DIRECTLY INTO A BUILDING CUMULUS WITH AN ESTIMATED TOP OF 25000 FT. AFTER ANOTHER FEW MINS, I LEVELED AT 11000 FT WITH CRUISE CONFIGN AND ASKED TO DEVIATE TO AVOID THE BUILDUP. AN EXASPERATED SOUNDING CTLR TOLD ME I COULD NOT DEVIATE W BUT DID ULTIMATELY GIVE ME A 100 DEG HDG. AFTER A FEW MINS THE CTLR TOLD ME THAT IF I COULD NOT FLY IN IMC HE WOULD HAVE TO RERTE ME TO VICTOR AIRWAYS MANY MI TO THE E OF MY CURRENT RTING BECAUSE HE SAID HE WOULD LOSE RADAR CONTACT OF ME. AT ABOUT THE SAME TIME I ACCEPTED THE NEW RTING, I WENT INTO IMC WITH LIGHT TO OCCASIONALLY MODERATE TURB. AFTER TRANSFERRING TO DENVER CENTER (135.6) A FEW MINS LATER, I WAS GIVEN A 110 DEG HDG AND 12000 FT TO JOIN VICTOR 19 INTO CHEYENNE (CYS). I ENCOUNTERED LITTLE TURB AND THE REMAINDER OF THE TRIP WAS UNEVENTFUL. I ATTRIBUTE THE ABOVE OCCURRENCE TO 1) UNEXPECTED CONVECTIVE ACTIVITY, 2) RISING TERRAIN, 3) GOOD VISUAL CONDITIONS REQUIRING OUTSIDE THE COCKPIT SCANNING, 4) A CTLR CONCERNED ABOUT TERRAIN CLRNC WHO OFFERED FEW OPTIONS TO AVOID CONVECTIVE ACTIVITY. BETTER MGMNT OF HDG WHILE VISUALLY SCANNING OUTSIDE THE ACFT AND PERHAPS BETTER COM TECHNIQUES SO AS TO AVOID AGGRAVATING THE CTLR, WOULD HAVE PREVENTED THIS OCCURRENCE.

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.