Narrative:

After leaving ZZZ en route jyo (approximately 325 degree heading, 22 NM) at 800-1000 ft MSL, I was talking to iad for clearance through en route. I was following my GPS readout in the HSI. Due to their takeoff/lndgs and the hazy conditions, dulles requested I fly straight for the control tower and cross midfield at altitude. I was 9 mi ene of dulles at this time. I started looking wsw for where the airport would have been from my original routing. Because of the haze, I could not make it out, so I programmed iad into our GPS. At that time, I looked up to see dulles 4 mi to my north. After my shock wore off, and I called dulles who told me to just maintain current heading, I realized that my HSI was greater than 30 degrees off of my magnetic compass heading. This has never happened before. I immediately looked to ensure I was in the slaved mode. There is no pilot fix or sync switch. Oddly, even though dulles knew where I started in their airspace (east going northeast), and knew they requested I fly over the top, and saw me when I was 4 mi due south, they never queried me. We are currently working the issue with maintenance, but believe the flux valves which feed the HSI information need replacing. The haze prevented me from possibly picking up this error sooner. I am also only 1 month new to this area, so ground reference points are still new to me. The incident is only that dulles asked me to cross over the tower and I crossed 4 mi south of the actives.

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Original NASA ASRS Text

Title: HELI PLT IS CLRED THROUGH IAD CLASS D AIRSPACE BUT FAILS TO CROSS AT ATC ISSUED LOCATION.

Narrative: AFTER LEAVING ZZZ ENRTE JYO (APPROX 325 DEG HDG, 22 NM) AT 800-1000 FT MSL, I WAS TALKING TO IAD FOR CLRNC THROUGH ENRTE. I WAS FOLLOWING MY GPS READOUT IN THE HSI. DUE TO THEIR TKOF/LNDGS AND THE HAZY CONDITIONS, DULLES REQUESTED I FLY STRAIGHT FOR THE CTL TWR AND CROSS MIDFIELD AT ALT. I WAS 9 MI ENE OF DULLES AT THIS TIME. I STARTED LOOKING WSW FOR WHERE THE ARPT WOULD HAVE BEEN FROM MY ORIGINAL ROUTING. BECAUSE OF THE HAZE, I COULD NOT MAKE IT OUT, SO I PROGRAMMED IAD INTO OUR GPS. AT THAT TIME, I LOOKED UP TO SEE DULLES 4 MI TO MY N. AFTER MY SHOCK WORE OFF, AND I CALLED DULLES WHO TOLD ME TO JUST MAINTAIN CURRENT HDG, I REALIZED THAT MY HSI WAS GREATER THAN 30 DEGS OFF OF MY MAGNETIC COMPASS HDG. THIS HAS NEVER HAPPENED BEFORE. I IMMEDIATELY LOOKED TO ENSURE I WAS IN THE SLAVED MODE. THERE IS NO PLT FIX OR SYNC SWITCH. ODDLY, EVEN THOUGH DULLES KNEW WHERE I STARTED IN THEIR AIRSPACE (E GOING NE), AND KNEW THEY REQUESTED I FLY OVER THE TOP, AND SAW ME WHEN I WAS 4 MI DUE S, THEY NEVER QUERIED ME. WE ARE CURRENTLY WORKING THE ISSUE WITH MAINT, BUT BELIEVE THE FLUX VALVES WHICH FEED THE HSI INFO NEED REPLACING. THE HAZE PREVENTED ME FROM POSSIBLY PICKING UP THIS ERROR SOONER. I AM ALSO ONLY 1 MONTH NEW TO THIS AREA, SO GND REF POINTS ARE STILL NEW TO ME. THE INCIDENT IS ONLY THAT DULLES ASKED ME TO CROSS OVER THE TWR AND I CROSSED 4 MI S OF THE ACTIVES.

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.