Narrative:

My student and I were operating on an IFR flight plan to fat. The enroute and arrival portion of our clearance was as follows: gmn tte tte.ALTTA8; cruising altitude 12;000. Just prior to tte ATC cleared us to descend to 6;000; expedite through 10;000. While descending; we crossed tte and got established on tte.ALTTA8 arrival (course from tte 323deg; minimum alt 3700). While descending on course at 7500 MSL ATC issued to us a low altitude alert; instructed to immediately turn left heading 270 and maintain 8000; and stated that we are below the MEA at our position. We complied; and upon ATC query confirmed that we are in VMC and have visual terrain clearance.after uneventful landing at our destination I called fresno TRACON to find out why we were issued a low altitude alert while 2;800 feet above minimum altitude for the arrival segment. ATC said that our flight appeared to be 4-5 NM off charted arrival course where the minimum altitudes are in excess of 9;000 compared to 3;700 minimum arrival altitude. However; our flight instruments showed us established on the published arrival segment; which is why the low altitude alert was completely unexpected to us. The contributing factors may be the lack of navigational guidance the pilots have while operating in VOR cone of confusion at high altitudes as well as aircraft and ATC radar limitations and malfunctions. While I don't know what caused this situation; I think to prevent situations like these from happening require accurate tracking and procedural flying by the pilots; in this instance the alert issued by the ATC was consistent with ATC procedures due to their belief that the aircraft was off-course in a sector with higher meas/mvas.

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Original NASA ASRS Text

Title: C210 instructor pilot reported receiving a low altitude alert from ATC when they had unknowingly deviated from their cleared track.

Narrative: My student and I were operating on an IFR flight plan to FAT. The enroute and arrival portion of our clearance was as follows: GMN TTE TTE.ALTTA8; cruising altitude 12;000. Just prior to TTE ATC cleared us to descend to 6;000; expedite through 10;000. While descending; we crossed TTE and got established on TTE.ALTTA8 arrival (course from TTE 323deg; minimum alt 3700). While descending on course at 7500 MSL ATC issued to us a low altitude alert; instructed to immediately turn left heading 270 and maintain 8000; and stated that we are below the MEA at our position. We complied; and upon ATC query confirmed that we are in VMC and have visual terrain clearance.After uneventful landing at our destination I called Fresno TRACON to find out why we were issued a low altitude alert while 2;800 feet above minimum altitude for the arrival segment. ATC said that our flight appeared to be 4-5 NM off charted arrival course where the minimum altitudes are in excess of 9;000 compared to 3;700 minimum arrival altitude. However; our flight instruments showed us established on the published arrival segment; which is why the low altitude alert was completely unexpected to us. The contributing factors may be the lack of navigational guidance the pilots have while operating in VOR cone of confusion at high altitudes as well as aircraft and ATC radar limitations and malfunctions. While I don't know what caused this situation; I think to prevent situations like these from happening require accurate tracking and procedural flying by the pilots; in this instance the alert issued by the ATC was consistent with ATC procedures due to their belief that the aircraft was off-course in a sector with higher MEAs/MVAs.

Data retrieved from NASA's ASRS site 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.