Could someone explain what the blue zipper line 'Atlantic Low Control Area' is in the images below?
What type of airspace is this? How far off the coast does it start? Would it still be G to 1200 and E to 18000 in this area? Is this related to a Warning area which begins 12 NM off the coast? Why are there two parallel lines? I'm not really sure what questions to ask about it but I want to understand it well enough to be able to explain it in a check ride.
The Atlantic Low Control Area is a Class E area in international airspace, where domestic ATC procedures may be used for separation procedures.
Here are the relevant excerpts from FAA Chapter 19. Other Airspace Areas Section 1. General
Offshore/Control Airspace Areas are locations designated in international airspace (between the U.S. 12-mile territorial limit and the CTA/FIR boundary, and within areas of domestic radio navigational signal or ATC radar coverage) wherein domestic ATC procedures may be used for separation purposes.
and
Class A Offshore/Control Airspace Areas are identified as “High" (e.g., Atlantic High; Control 1154H). Class E areas are identified as “Low" (e.g., Gulf of Mexico Low, Control 1141L)
The two parallel lines differentiate floors of class E airspace that is neither 700 feet nor 1200 feet AGL (Above Ground Level).
About the jagged lines from http://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/aero_guide/:
Class E Airspace exists at 1200' AGL unless designated otherwise. The lateral and vertical limits of all Class E, (up to, but not including 18,000') are shown by narrow bands of vignette on Sectionals and TACs.
Controlled airspace floors of 700' above the ground are defined by a magenta vignette; floors other than 700' that laterally abut uncontrolled airspace (Class G) are defined by a blue vignette; differing floors greater than 700' above the ground are annotated by a symbol and a number indicating the floor.
If the ceiling is less than 18,000' MSL, the value (preceded by the word "ceiling") is shown along the limits of the controlled airspace. These limits are shown with the same symbol indicated above.
A little more search say that it is the floor altitude of that control area. The parallel lines are when the floor altitude changes (from 1300 MSL to 2700MSL and 1700MSL to 5500MSL).
