Mode C veil

Mode C veil refers to a kind of airspace which surrounds most of primary Class B airports within United States. This airspace extends horizontally to a circle of 30 NM radius centered on the airport and extends vertically from the surface up to 10,000 feet MSL.^[1] The name refers to the mode of transponder operation which is required within this airspace. Out of 37 existing (as of late 2011) Class B airports in the United States,^[2] 35 airports (i.e., all but 2) have Mode C veil centered on them.^[3] The only two that don't are Houston Hobby Airport and Miramar Naval Air Station.^[4]

References

1. ^ 14 C.F.R. 91.215(b)(2)
2. ^ FAA's order JO 7400.9V, effective 2011-09-15, accessed 2011-09-17
3. ^ CFR Title 14 Appendix D to Part 91, Section 1
4. ^ As of October 2011, both of these exceptions had Mode C veils centered on them on the sectional, WAC, and Low IFR charts, which is inconsistent with CFR and as such is either a cartographic or a regulatory mistake.