B737-700 captain reported overshooting an altitude restriction on the comix arrival into san.

Attributes
ACN	1552232
Time
Date	201806
Local Time Of Day	1801-2400
Place
Locale Reference	SAN.Airport
State Reference	CA
Environment
Flight Conditions	Mixed
Light	Night
Aircraft 1
Make Model Name	B737-700
Operating Under FAR Part	Part 121
Flight Phase	Initial Approach
Route In Use	STAR COMIX
Flight Plan	IFR
Person 1
Function	Pilot Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 436
Events
Anomaly	Deviation - Altitude Crossing Restriction Not Met Deviation - Altitude Overshoot Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy

Narrative:

Held up and vectored off comix arrival then cleared back onto the arrival. Next we were quite high and around 20 miles from klomn when we were told to cross klomn at 6000 ft and cleared RNAV Z 27 maintain 250 KIAS. I put 6000 ft in the altitude window and selected level change 250 KIAS. As we were approaching VNAV path; ATC told us to slow to 200 KIAS. I selected 200 KIAS and continued in level change. Also; I used the speedbrakes and flaps 10. As we approached klomn; I thought we were high and to keep the aircraft descending I entered the next altitude. I miscalculated and the aircraft descended to 5600 ft at klomn. The first officer called out the deviation and I corrected the flight path. The remainder of the approach was uneventful. ATC did not comment.

Original NASA ASRS Text

Title: B737-700 Captain reported overshooting an altitude restriction on the COMIX arrival into SAN.

Narrative: Held up and vectored off COMIX Arrival then cleared back onto the arrival. Next we were quite high and around 20 miles from KLOMN when we were told to cross KLOMN at 6000 ft and cleared RNAV Z 27 maintain 250 KIAS. I put 6000 ft in the altitude window and selected Level Change 250 KIAS. As we were approaching VNAV PATH; ATC told us to slow to 200 KIAS. I selected 200 KIAS and continued in Level Change. Also; I used the speedbrakes and flaps 10. As we approached KLOMN; I thought we were high and to keep the aircraft descending I entered the next altitude. I miscalculated and the aircraft descended to 5600 ft at KLOMN. The First Officer called out the deviation and I corrected the flight path. The remainder of the approach was uneventful. ATC did not comment.

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.