Ce-560 pilot reported receiving a low altitude alert from the tower on approach to san.

Attributes
ACN	1554116
Time
Date	201806
Local Time Of Day	0601-1200
Place
Locale Reference	SAN.Tower
State Reference	CA
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Make Model Name	Citation V/Ultra/Encore (C560)
Operating Under FAR Part	Part 91
Flight Phase	Final Approach
Flight Plan	IFR
Person 1
Function	Pilot Flying Single Pilot
Qualification	Flight Crew Multiengine Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 12 Flight Crew Total 20000 Flight Crew Type 135
Events
Anomaly	Deviation - Procedural Published Material / Policy Deviation - Procedural Clearance Deviation - Track / Heading All Types Inflight Event / Encounter CFTT / CFIT

Narrative:

I was being vectored for the RNAV (GPS) Y runway 27 into san. The controller gave me the final heading for intercept and clearance for the approach. I turned to the heading; switched to tower; and began to descend. A few seconds later tower informed me I was north of course so I made a correction bock to the south to get back on course. I broke out at approximately 800 feet and saw the runway and terrain. About 1 or 2 seconds later the tower informed me of a low altitude alert. At which time I was in VMC and informed the tower I had the field in sight; and continued on to landing. The cause of the problem was that when I was given the last heading and clearance for the approach I forgot to arm the nav mode and remained in heading mode. I then made too large [a turn] back to course and then lost sa.

Original NASA ASRS Text

Title: CE-560 pilot reported receiving a low altitude alert from the Tower on approach to SAN.

Narrative: I was being vectored for the RNAV (GPS) Y Runway 27 into SAN. The controller gave me the final heading for intercept and clearance for the approach. I turned to the heading; switched to Tower; and began to descend. A few seconds later Tower informed me I was north of course so I made a correction bock to the south to get back on course. I broke out at approximately 800 feet and saw the runway and terrain. About 1 or 2 seconds later the Tower informed me of a low altitude alert. At which time I was in VMC and informed the Tower I had the field in sight; and continued on to landing. The cause of the problem was that when I was given the last heading and clearance for the approach I forgot to arm the nav mode and remained in heading mode. I then made too large [a turn] back to course and then lost SA.

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.