An experienced pilot nearly collided with a radio tower on an ILS approach to pdk.

Attributes
ACN	457482
Time
Date	199912
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : pdk.airport
State Reference	GA
Altitude	agl single value : 200
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Operator	general aviation : personal
Make Model Name	Small Aircraft
Operating Under FAR Part	Part 91
Navigation In Use	ils localizer & glide slope : 20l
Flight Phase	descent : approach
Route In Use	approach : instrument precision
Flight Plan	IFR
Person 1
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : atp
Experience	flight time last 90 days : 10 flight time total : 25000 flight time type : 350
ASRS Report	457482
Person 2
Affiliation	government : faa
Function	controller : local
Qualification	controller : radar
Events
Anomaly	aircraft equipment problem : critical conflict : airborne critical
Independent Detector	other flight crewa
Resolutory Action	none taken : detected after the fact
Miss Distance	vertical : 200
Supplementary
Problem Areas	Flight Crew Human Performance Aircraft
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

I then proceeded to pdk since that airport has an ILS and aircraft was getting in ok. Shortly after passing morrow intersection, the GS indicator moved down and when it centered, I followed the GS. Stupidly, I did not wait for the marker light at OM. Result, I was too low, too far out and nearly collided with the tower's underlying the ILS. This problem happened once before in my airplane while in visual conditions. The radio shop checked my GS equipment and found no problem, so I assumed the problem was with the aircraft equipment and test flew the airplane at mcn, GA, after this incident and the equipment worked fine. I know that after 43 yrs of flying, this was the closest I have come to getting killed, where I was in control. I am now retired from a major airline and we always had a procedure to verify the altimeters at the OM. I always thought this was to verify altimeter accuracy, but now realize, that would also verify that the GS is working properly. I lost my situational awareness on this approach and should have used the DME information to confirm my position.

Original NASA ASRS Text

Title: AN EXPERIENCED PLT NEARLY COLLIDED WITH A RADIO TWR ON AN ILS APCH TO PDK.

Narrative: I THEN PROCEEDED TO PDK SINCE THAT ARPT HAS AN ILS AND ACFT WAS GETTING IN OK. SHORTLY AFTER PASSING MORROW INTXN, THE GS INDICATOR MOVED DOWN AND WHEN IT CTRED, I FOLLOWED THE GS. STUPIDLY, I DID NOT WAIT FOR THE MARKER LIGHT AT OM. RESULT, I WAS TOO LOW, TOO FAR OUT AND NEARLY COLLIDED WITH THE TWR'S UNDERLYING THE ILS. THIS PROB HAPPENED ONCE BEFORE IN MY AIRPLANE WHILE IN VISUAL CONDITIONS. THE RADIO SHOP CHKED MY GS EQUIP AND FOUND NO PROB, SO I ASSUMED THE PROB WAS WITH THE ACFT EQUIP AND TEST FLEW THE AIRPLANE AT MCN, GA, AFTER THIS INCIDENT AND THE EQUIP WORKED FINE. I KNOW THAT AFTER 43 YRS OF FLYING, THIS WAS THE CLOSEST I HAVE COME TO GETTING KILLED, WHERE I WAS IN CTL. I AM NOW RETIRED FROM A MAJOR AIRLINE AND WE ALWAYS HAD A PROC TO VERIFY THE ALTIMETERS AT THE OM. I ALWAYS THOUGHT THIS WAS TO VERIFY ALTIMETER ACCURACY, BUT NOW REALIZE, THAT WOULD ALSO VERIFY THAT THE GS IS WORKING PROPERLY. I LOST MY SITUATIONAL AWARENESS ON THIS APCH AND SHOULD HAVE USED THE DME INFO TO CONFIRM MY POS.

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.