BE35 pilot reports descending early on the ILS runway 23 into orf due to improper setup of nav panel...

Narrative:

While I was flying an ILS approach to runway 23 at orf; the approach controller reported to me that he had received a low altitude alert. I informed him that I was in good VMC; and I elected to continue at my altitude (800 feet MSL; over open water) rather than climb. He informed me a second time; at which point I climbed to the altitude for the approach; continued; and landed without incident. The situation developed as follows: in my airplane I have a GNS 430W (navigation 1) and an SL30 navigation/comm (navigation 2). My standard procedure is to use NAV2 for an ILS; reacquired. Since my experience is that once an ILS signal comes in; it stays in (especially since I was not at a sever angle to the approach course) I was not sure I could trust navigation 2; so I set up the ILS frequency in navigation 1; with the intention of switching the CDI from GPS to vloc (VOR/localizer). I was given direct klink and then fly the approach (no procedure turn) so I (re)programmed the GPS klink-korf. Upon reaching klink I turned in on the approach; but I neglected to switch the CDI. However; I thought that I had done so; and so followed the indications on navigation 1; which had me on course laterally (which was correct) and also vertically (which; of course; was not). I also overlooked the fact that the GS (not received) flag was showing on navigation 1.basically; I just saw what I expected to see. I will have to be more diligent in the future. Upon my return home later that afternoon; when I had to fly an ILS (ceiling 800 overcast); I selected the ILS on both navigation 1 and navigation 2; and got identical needle movement; so there had been nothing wrong with navigation 2 and the ILS signal for the approach at orf must just have been weak. By the time of the flight home; I had figured out what had happened; and was trying not only to be extra careful on the approach; but also deliberately comparing the two ILS signals to see whether I had a problem with my instruments.

Original NASA ASRS Text

Title: BE35 pilot reports descending early on the ILS RWY 23 into ORF due to improper setup of Nav panel. ATC issues a low altitude alert and the reporter eventually climbs back to 1;600 feet from 800 feet.

Narrative: While I was flying an ILS approach to Runway 23 at ORF; the approach controller reported to me that he had received a low altitude alert. I informed him that I was in good VMC; and I elected to continue at my altitude (800 feet MSL; over open water) rather than climb. He informed me a second time; at which point I climbed to the altitude for the approach; continued; and landed without incident. The situation developed as follows: In my airplane I have a GNS 430W (NAV 1) and an SL30 NAV/COMM (NAV 2). My standard procedure is to use NAV2 for an ILS; reacquired. Since my experience is that once an ILS signal comes in; it stays in (especially since I was not at a sever angle to the approach course) I was not sure I could trust NAV 2; so I set up the ILS frequency in NAV 1; with the intention of switching the CDI from GPS to VLOC (VOR/LOC). I was given direct KLINK and then fly the approach (no Procedure Turn) so I (re)programmed the GPS KLINK-KORF. Upon reaching KLINK I turned in on the approach; but I neglected to switch the CDI. However; I thought that I had done so; and so followed the indications on NAV 1; which had me on course laterally (which was correct) and also vertically (which; of course; was not). I also overlooked the fact that the GS (not received) flag was showing on NAV 1.Basically; I just saw what I expected to see. I will have to be more diligent in the future. Upon my return home later that afternoon; when I had to fly an ILS (ceiling 800 overcast); I selected the ILS on both NAV 1 and NAV 2; and got identical needle movement; so there had been nothing wrong with NAV 2 and the ILS signal for the approach at ORF must just have been weak. By the time of the flight home; I had figured out what had happened; and was trying not only to be extra careful on the approach; but also deliberately comparing the two ILS signals to see whether I had a problem with my instruments.

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.

Attributes
ACN	1252292
Time
Date	201503
Local Time Of Day	1201-1800
Place
Locale Reference	ORF.Airport
State Reference	VA
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Bonanza 35
Operating Under FAR Part	Part 91
Flight Phase	Final Approach
Flight Plan	IFR
Component
Aircraft Component	ILS/VOR
Person 1
Function	Pilot Flying Single Pilot
Qualification	Flight Crew Instrument Flight Crew Private
Experience	Flight Crew Last 90 Days 30 Flight Crew Total 2600 Flight Crew Type 800
Events
Anomaly	Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance Inflight Event / Encounter CFTT / CFIT

BE35 pilot reports descending early on the ILS runway 23 into orf due to improper setup of nav panel. ATC issues a low altitude alert and the reporter eventually climbs back to 1;600 feet from 800 feet.