A CL601 crew approaching san acknowledged TRACON's clearance to 3;800'. After realizing terrain clea...

Attributes
ACN	858204
Time
Date	200910
Local Time Of Day	0601-1200
Place
Locale Reference	SAN.Airport
State Reference	CA
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Challenger CL601
Operating Under FAR Part	Part 91
Flight Phase	Descent Initial Approach
Flight Plan	IFR
Person 1
Function	First Officer Pilot Not Flying
Qualification	Flight Crew Multiengine Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument
Experience	Flight Crew Total 15900
Person 2
Function	Pilot Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Multiengine Flight Crew Commercial Flight Crew Flight Instructor Flight Crew Instrument
Experience	Flight Crew Last 90 Days 45 Flight Crew Total 18000 Flight Crew Type 5000
Events
Anomaly	ATC Issue All Types Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance

Narrative:

Socal approach had cleared us to 5000 ft for vectors to localizer runway 27 approach to san under visual conditions. At approximately 18 to 20 miles out we were instructed to turn right heading 270 degrees to intercept localizer runway 27 and descend to 3800 ft. Both pilots confirmed clearances and readback to controller exactly as cleared. I should state at this time that the controller was; in my opinion; under a very heavy load vectoring multiple aircraft to different airports. Upon reaching 3800 ft on the localizer runway 27; both pilots observed that we were at the same terrain level as the tops of approaching mountains in both sides ahead of us. We immediately tried to confirm the altitude assigned with the controller but were unable due to his workload issuing instructions to other aircraft. Within a few seconds the controller called us with an immediate climb back to 5000 ft. We did so and confirmed that we readback his original clearance to 3800 ft. He then said that clearance was for another aircraft. At 5000 ft and within 12 miles we were cleared for visual to runway 27. The following should be noted: the controller did not confirm our readback of heading or descent to 3800 ft. I am unaware of the limit of how many aircraft a controller can safely handle but he seemed to be near that limit. Since we were approaching a valley with tops on each side; we never received a terrain warning. Visibility was 10 plus.

Original NASA ASRS Text

Title: a CL601 crew approaching SAN acknowledged TRACON's clearance to 3;800'. After realizing terrain clearance was low and ATC issuing a 'Low Altitude Alert' the crew climbed to 5;000'. The crew believed a busy Controller mistakenly issued the 3;800' clearance.

Narrative: SOCAL Approach had cleared us to 5000 FT for vectors to Localizer Runway 27 approach to SAN under visual conditions. At approximately 18 to 20 miles out we were instructed to turn R heading 270 degrees to intercept Localizer Runway 27 and descend to 3800 FT. Both pilots confirmed clearances and readback to Controller exactly as cleared. I should state at this time that the Controller was; in my opinion; under a very heavy load vectoring multiple aircraft to different airports. Upon reaching 3800 FT on the Localizer Runway 27; both pilots observed that we were at the same terrain level as the tops of approaching mountains in both sides ahead of us. We immediately tried to confirm the altitude assigned with the Controller but were unable due to his workload issuing instructions to other aircraft. Within a few seconds the Controller called us with an immediate climb back to 5000 FT. We did so and confirmed that we readback his original clearance to 3800 FT. He then said that clearance was for another aircraft. At 5000 Ft and within 12 miles we were cleared for visual to Runway 27. The following should be noted: The Controller did not confirm our readback of heading or descent to 3800 FT. I am unaware of the limit of how many aircraft a Controller can safely handle but he seemed to be near that limit. Since we were approaching a valley with tops on each side; we never received a terrain warning. Visibility was 10 plus.

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.

A CL601 crew approaching san acknowledged TRACON's clearance to 3;800'. After realizing terrain clearance was low and ATC issuing a 'low altitude alert' the crew climbed to 5;000'. The crew believed a busy controller mistakenly issued the 3;800' clearance.