A flight crew executed two missed approaches to pdk runway 21L because of a localizer discrepancy wh...

Narrative:

When on the approach (ILS 21) at 3;000 feet out side of chamb we were given vectors to join the localizer and cleared for the approach. We were then instructed to contact tower. As we attempted to join the localizer we both noticed green needle deviation to the right then full deflection. We both agreed to go missed approach and I contacted tower and informed them that we were going missed approach. Tower asked us to repeat and I did. We immediately executed the published missed approach instructions from the approach plate. Shortly thereafter tower said they would give us a heading which they did. The published missed altitude was 4;000 ft which [we] proceeded to climb to. Tower instructed us to contact atlanta approach and we did. Approach asked what altitude we had been given and we responded the published 4;000 feet. They instructed [us] back down to 3;000 feet and asked our intentions. We said we needed vectors for another ILS approach. We tried a second attempt and found the same navigation deviation. We then asked for the RNAV (GPS) Y runway 21L. We executed that approach successfully and landed with no problems. After aircraft shut down on the ramp I contacted the tower to ask if there had been any other reported issues of the ILS 21L. They said in the past there had been but not two in a row.

Original NASA ASRS Text

Title: A flight crew executed two missed approaches to PDK Runway 21L because of a localizer discrepancy which ATC said occurs occasionally. No warnings were given to the crew who ultimately landed off the RNAV GPS Y Runway 21L approach.

Narrative: When on the approach (ILS 21) at 3;000 feet out side of CHAMB we were given vectors to join the localizer and cleared for the approach. We were then instructed to contact Tower. As we attempted to join the localizer we both noticed green needle deviation to the right then full deflection. We both agreed to go missed approach and I contacted Tower and informed them that we were going missed approach. Tower asked us to repeat and I did. We immediately executed the published missed approach instructions from the approach plate. Shortly thereafter Tower said they would give us a heading which they did. The published missed altitude was 4;000 FT which [we] proceeded to climb to. Tower instructed us to contact Atlanta Approach and we did. Approach asked what altitude we had been given and we responded the published 4;000 feet. They instructed [us] back down to 3;000 feet and asked our intentions. We said we needed vectors for another ILS approach. We tried a second attempt and found the same NAV deviation. We then asked for the RNAV (GPS) Y Runway 21L. We executed that approach successfully and landed with no problems. After aircraft shut down on the ramp I contacted the Tower to ask if there had been any other reported issues of the ILS 21L. They said in the past there had been but not two in a row.

Data retrieved from NASA's ASRS site as of July 2013 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.

Attributes
ACN	1109709
Time
Date	201308
Local Time Of Day	1201-1800
Place
Locale Reference	PDK.Airport
State Reference	GA
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Make Model Name	Light Transport Low Wing 2 Turbojet Eng
Operating Under FAR Part	Part 91
Flight Phase	Initial Approach
Flight Plan	IFR
Person 1
Function	First Officer Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Person 2
Function	Pilot Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	ATC Issue All Types Inflight Event / Encounter Unstabilized Approach

A flight crew executed two missed approaches to pdk runway 21L because of a localizer discrepancy which ATC said occurs occasionally. No warnings were given to the crew who ultimately landed off the RNAV GPS Y runway 21L approach.