Cessna 182 pilot reported being alerted by air traffic control that localizer approach was not worki...

Narrative:

During the approach to hdc; new orleans was vectoring me for the ILS to runway 18. They gave me a heading to join the localizer and cleared me for the ILS to runway 18. Moments later they ask if I was receiving the localizer; and advised me that a previous aircraft had let them know that they had not received it. I replied that I was not receiving the localizer; and they ask if I would like the RNAV to runway 18. I replied yes; and they immediately cleared me for the RNAV to runway 18. I had expected that ATC was going to vector me back around in a box pattern to set up for the RNAV to runway 18; and when they simply cleared me for that approach; I started scrambling; since I was single pilot to reset the radios for the approach and join the inbound course. I was able to join the inbound course; a couple of miles outside the FAF; however upon being handed over to hdc tower; tower immediately advised me of a low altitude alert from new orleans approach. I had descended below the minimum altitude on the approach; prior to the FAF. I broke out of the clouds into VMC at approximately 1200 ft.; 600 ft. Below the minimum altitude. I believe that the cause for this event is my failure to not accept the clearance for an approach that I was not completely set up and ready for. I should have asked for vectors in a box pattern to join the approach; and give myself time to fully brief the approach; have the radios set up; and be completely prepared prior to joining the final approach course. My hurried effort to set up the radios for the approach and join the course distracted me from flying the airplane and cause me to bust the altitude.

Original NASA ASRS Text

Title: Cessna 182 Pilot reported being alerted by Air Traffic Control that LOC Approach was not working and therefore being cleared for an RNAV approach completely unprepared which caused a descent below minimum altitude.

Narrative: During the approach to HDC; New Orleans was vectoring me for the ILS to Runway 18. They gave me a heading to join the LOC and cleared me for the ILS to Runway 18. Moments later they ask if I was receiving the LOC; and advised me that a previous aircraft had let them know that they had not received it. I replied that I was not receiving the LOC; and they ask if I would like the RNAV to Runway 18. I replied yes; and they immediately cleared me for the RNAV to Runway 18. I had expected that ATC was going to vector me back around in a box pattern to set up for the RNAV to Runway 18; and when they simply cleared me for that approach; I started scrambling; since I was single pilot to reset the radios for the approach and join the inbound course. I was able to join the inbound course; a couple of miles outside the FAF; however upon being handed over to HDC Tower; Tower immediately advised me of a low altitude alert from New Orleans Approach. I had descended below the minimum altitude on the approach; prior to the FAF. I broke out of the clouds into VMC at approximately 1200 ft.; 600 ft. below the minimum altitude. I believe that the cause for this event is my failure to NOT accept the clearance for an approach that I was not completely set up and ready for. I should have asked for vectors in a box pattern to join the approach; and give myself time to fully brief the approach; have the radios set up; and be completely prepared prior to joining the final approach course. My hurried effort to set up the radios for the approach and join the course distracted me from flying the airplane and cause me to bust the altitude.

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	1742941
Time
Date	202005
Local Time Of Day	0601-1200
Place
Locale Reference	HDC.Airport
State Reference	LA
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Make Model Name	Skylane 182/RG Turbo Skylane/RG
Operating Under FAR Part	Part 91
Flight Phase	Initial Approach
Route In Use	Vectors
Flight Plan	IFR
Person 1
Function	Single Pilot
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Flight Instructor
Experience	Flight Crew Last 90 Days 80 Flight Crew Total 15000 Flight Crew Type 100
Events
Anomaly	ATC Issue All Types Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy Inflight Event / Encounter CFTT / CFIT

Cessna 182 pilot reported being alerted by air traffic control that localizer approach was not working and therefore being cleared for an RNAV approach completely unprepared which caused a descent below minimum altitude.