Narrative:

Inbound to atl, we were being issued vectors for traffic approaching foothills. After passing foothills, we were told to hold as depicted at macey intersection. We asked for 20 mi legs and our request was approved. We entered the first turn normally, reported entering holding, and proceeded to fly the pattern using the DME from foothills as depicted. On the first pattern, we determined the wind correction needed to maintain a symmetrical pattern in the protected airspace, and applied the correction on the second pattern. Approaching foothills from the south, the DME slowed and by the time I noticed it the compass needle was pointing nearly 90 degrees. I immediately began my inbound turn (not having completed the 20 mi leg according to the DME). I may have exceeded my protected airspace due to not having allowed for the angular factor which had to be taken into account when operating so close to the foothills VOR on the outbnd leg of the holding pattern. The DME point at which the turn inbound to macey should have begun was 9 mi from foothills. The outbnd leg was some 10 mi from the centerline of the inbound course, thus the DME form foothills should not have been used, but rather the DME off of atl, even though it was much farther away. A very valuable lesson has been learned. When asking for longer legs than depicted, consider the need to back up navigation fixes that may be unreliably depicted by DME if the request is granted.

Related reports:

Google
 

Original NASA ASRS Text

Title: REPORTER FLYING HOLDING PATTERN AT MACEY MAY HAVE EXCEEDED PROTECTED SPACE IN 20 MILE LEG HOLDING PATTERN.

Narrative: INBND TO ATL, WE WERE BEING ISSUED VECTORS FOR TFC APCHING FOOTHILLS. AFTER PASSING FOOTHILLS, WE WERE TOLD TO HOLD AS DEPICTED AT MACEY INTXN. WE ASKED FOR 20 MI LEGS AND OUR REQUEST WAS APPROVED. WE ENTERED THE FIRST TURN NORMALLY, RPTED ENTERING HOLDING, AND PROCEEDED TO FLY THE PATTERN USING THE DME FROM FOOTHILLS AS DEPICTED. ON THE FIRST PATTERN, WE DETERMINED THE WIND CORRECTION NEEDED TO MAINTAIN A SYMMETRICAL PATTERN IN THE PROTECTED AIRSPACE, AND APPLIED THE CORRECTION ON THE SECOND PATTERN. APCHING FOOTHILLS FROM THE S, THE DME SLOWED AND BY THE TIME I NOTICED IT THE COMPASS NEEDLE WAS POINTING NEARLY 90 DEGS. I IMMEDIATELY BEGAN MY INBND TURN (NOT HAVING COMPLETED THE 20 MI LEG ACCORDING TO THE DME). I MAY HAVE EXCEEDED MY PROTECTED AIRSPACE DUE TO NOT HAVING ALLOWED FOR THE ANGULAR FACTOR WHICH HAD TO BE TAKEN INTO ACCOUNT WHEN OPERATING SO CLOSE TO THE FOOTHILLS VOR ON THE OUTBND LEG OF THE HOLDING PATTERN. THE DME POINT AT WHICH THE TURN INBND TO MACEY SHOULD HAVE BEGUN WAS 9 MI FROM FOOTHILLS. THE OUTBND LEG WAS SOME 10 MI FROM THE CENTERLINE OF THE INBND COURSE, THUS THE DME FORM FOOTHILLS SHOULD NOT HAVE BEEN USED, BUT RATHER THE DME OFF OF ATL, EVEN THOUGH IT WAS MUCH FARTHER AWAY. A VERY VALUABLE LESSON HAS BEEN LEARNED. WHEN ASKING FOR LONGER LEGS THAN DEPICTED, CONSIDER THE NEED TO BACK UP NAV FIXES THAT MAY BE UNRELIABLY DEPICTED BY DME IF THE REQUEST IS GRANTED.

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.