PA28 pilot practicing GPS runway 32 at cxo in VFR conditions reports receiving low altitude alert fr...

Narrative:

I was on a solo IFR flight plan practice flight in VFR conditions and was returning to cxo on a GPS runway 32 @ cxo. I was practicing doing approaches with the autopilot and intercepted riley and was enroute to norle (FAF). My GPS evidently was set up for a hold pattern that was not required or directed by houston approach. I tried to adjust the GPS but decided it would be prudent to disarm the autopilot and manually follow the approach. When I passed the norle (FAF) I notified the cxo tower I was at the FAF and started my descent for the landing. The tower contacted me a short time later and said approach had received a low altitude alarm and I immediately stopped my descent. It should be noted that at the point I notified the tower I was at the FAF I also had visual contact of the airport. My understanding is that once you pass the FAF you can descend to an altitude no lower than the da of 640 feet until the airport is in sight. I believe I maintained an altitude of at least 2000 feet until I assumed I passed the FAF and then started my descent but based on the fact that approach received an alarm I must have misread the GPS and had not reached the FAF before starting my descent. A lesson learned was to make sure my range on the GPS is zoomed in to a range that would not leave any doubt that the FAF had been reached prior to starting the next phase of the approach. I also will review the operators manual for the GPS to make sure I have a better understanding on how to adjust the flight plan when it is has a holding pattern as the next step but not required for the approach. I will continue to file IFR flight plans for all of my flights and do practice approaches using the autopilot in VFR conditions until I become proficient utilizing the tool. Until I am very confident in my understanding of the autopilot all approaches in IFR conditions will be flown manually.

Original NASA ASRS Text

Title: PA28 pilot practicing GPS RWY 32 at CXO in VFR conditions reports receiving low altitude alert from tower. Reporter believes the descent to DA was commenced at the FAF and is not clear why the alert was issued.

Narrative: I was on a solo IFR flight plan practice flight in VFR conditions and was returning to CXO on a GPS RWY 32 @ CXO. I was practicing doing approaches with the autopilot and intercepted RILEY and was enroute to NORLE (FAF). My GPS evidently was set up for a hold pattern that was not required or directed by Houston approach. I tried to adjust the GPS but decided it would be prudent to disarm the autopilot and manually follow the approach. When I passed the NORLE (FAF) I notified the CXO Tower I was at the FAF and started my descent for the landing. The tower contacted me a short time later and said approach had received a low altitude alarm and I immediately stopped my descent. It should be noted that at the point I notified the tower I was at the FAF I also had visual contact of the airport. My understanding is that once you pass the FAF you can descend to an altitude no lower than the DA of 640 feet until the airport is in sight. I believe I maintained an altitude of at least 2000 feet until I assumed I passed the FAF and then started my descent but based on the fact that approach received an alarm I must have misread the GPS and had not reached the FAF before starting my descent. A lesson learned was to make sure my range on the GPS is zoomed in to a range that would not leave any doubt that the FAF had been reached prior to starting the next phase of the approach. I also will review the operators manual for the GPS to make sure I have a better understanding on how to adjust the flight plan when it is has a holding pattern as the next step but not required for the approach. I will continue to file IFR flight plans for all of my flights and do practice approaches using the autopilot in VFR conditions until I become proficient utilizing the tool. Until I am very confident in my understanding of the autopilot all approaches in IFR conditions will be flown manually.

Data retrieved from NASA's ASRS site as of April 2012 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	835776
Time
Date	200905
Local Time Of Day	1801-2400
Place
Locale Reference	CXO.Airport
State Reference	TX
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	PA-28 Cherokee/Archer/Dakota/Pillan/Warrior
Operating Under FAR Part	Part 91
Flight Phase	Final Approach
Route In Use	Visual Approach
Flight Plan	IFR
Person 1
Function	Pilot Flying Single Pilot
Qualification	Flight Crew Private
Experience	Flight Crew Last 90 Days 36.7 Flight Crew Total 232.8 Flight Crew Type 232.8
Events
Anomaly	Deviation - Procedural Published Material / Policy Deviation - Procedural Clearance

PA28 pilot practicing GPS runway 32 at cxo in VFR conditions reports receiving low altitude alert from tower. Reporter believes the descent to da was commenced at the FAF and is not clear why the alert was issued.