An air taxi first officer reported that the crew descended below the 1;120 ft culve intersection alt...

Attributes
ACN	975744
Time
Date	201110
Local Time Of Day	0601-1200
Place
Locale Reference	SMO.Tower
State Reference	CA
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Make Model Name	Light Transport Low Wing 2 Turbojet Eng
Operating Under FAR Part	Part 135
Flight Phase	Final Approach
Flight Plan	IFR
Person 1
Function	First Officer Pilot Not Flying
Qualification	Flight Crew Multiengine Flight Crew Instrument Flight Crew Air Transport Pilot (ATP) Flight Crew Flight Instructor
Experience	Flight Crew Last 90 Days 150 Flight Crew Total 5700 Flight Crew Type 120
Events
Anomaly	Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Published Material / Policy Inflight Event / Encounter CFTT / CFIT

Narrative:

While executing the GPS a approach into smo we were given a low altitude alert by the santa monica tower. We were also given a caution message for obstacles/terrain by our terrain avoidance system in the airplane. The issue occurred while crossing the culve intersection. The captain and I are both ATP qualified pilots both previously working for part 121 air carriers. We briefed the approach using nos approach charts. We looked at the section in regards to culve intersection and felt that we could properly identify it. That meant 1 mile visibility required and a MDA of 680 ft. We began the approach and after bevey intersection descended down to 680 ft. We soon realized that we were supposed to go to 1;120 ft then after culve descend to 680 ft. We were visual by that point of the warnings and could continue safely to the runway. The reason I write this report is because we made a mistake but I also believe the chart makes this very confusing.

Original NASA ASRS Text

Title: An Air Taxi First Officer reported that the crew descended below the 1;120 FT CULVE intersection altitude constraint on the SMO VOR/GPS A approach and receive an ATC low altitude alert and terrain warning.

Narrative: While executing the GPS A approach into SMO we were given a low altitude alert by the Santa Monica Tower. We were also given a caution message for obstacles/terrain by our terrain avoidance system in the airplane. The issue occurred while crossing the CULVE Intersection. The Captain and I are both ATP qualified pilots both previously working for Part 121 air carriers. We briefed the approach using NOS approach charts. We looked at the section in regards to CULVE Intersection and felt that we could properly identify it. That meant 1 mile visibility required and a MDA of 680 FT. We began the approach and after BEVEY Intersection descended down to 680 FT. We soon realized that we were supposed to go to 1;120 FT then after CULVE descend to 680 FT. We were visual by that point of the warnings and could continue safely to the runway. The reason I write this report is because we made a mistake but I also believe the chart makes this very confusing.

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.

An air taxi first officer reported that the crew descended below the 1;120 ft culve intersection altitude constraint on the smo VOR/GPS a approach and receive an ATC low altitude alert and terrain warning.