Comprehensive Aviation Notes: Classes D, E, G, and Special Use Airspace

Overview of Class D (Class Delta) Airspace

• Definition and Popularity: Class D airspace is widely recognized as the airspace general aviation pilots love most. It is characterized as being less busy than Class B or Class C airspaces and is relatively easy to navigate for small aircraft.

• Visual Representation on Charts:

  • On a sectional chart, Class D is indicated by a blue dashed line surrounding the airport.

  • Example: Salina Airport is surrounded by a blue dashed ring, marking it as Class Delta.

• Vertical Boundaries:

  • The Floor: Class D airspace always starts at the surface (ground level). Because the floor is constant, no fraction is used on the chart to denote the starting altitude.

  • The Ceiling: The ceiling is indicated by a number inside a dashed blue box (square brackets).

  • The number in the box represents the altitude in hundreds of feet Mean Sea Level ($\text{MSL}$).

  • Example: A box containing the number "38" indicates a ceiling of $3,800\,\text{feet MSL}$.

• The "Balling on a Budget" Metaphor:

  • While Class B is an expensive, multi-tiered wedding cake and Class C is a two-tiered budget cake, Class D is compared to a "Dairy Queen ice cream cake."

  • If you drop an ice cream cake, it has no tiers; it simply hits the ground. Similarly, Class D always starts at the ground/surface and has no multiple shelves or tiers.

• Operational Requirements:

  • Pilot or drone operators must have authorization to fly within Class D airspace.

  • All Class D airports possess a control tower. However, unlike Class B or C, the tower may not be operational $24$ hours a day. It will be open at some point during the day.

• Spatial Dimensions:

  • While not a guaranteed rule $100\%$ of the time, the vast majority of Class D airspaces have a radius of roughly $5\,\text{nautical miles}$ from the airport to the edge of the blue dashed line.

Class E (Class Echo) Airspace: The "Everywhere" Airspace

• General Characterization: Class E is frequently referred to as starting "Everywhere." It is considered one of the more complex airspaces to understand because its floor begins at different altitudes depending on the chart's symbology.

• Altitudes of Inception (The Floor): There are three primary altitudes at which Class Echo can begin:

  1. Surface (SFC): Indicated by a dashed magenta line.

  2. $700\,\text{feet AGL}$ (Above Ground Level): Indicated by a shaded or faded magenta ring (soft magenta).

  3. $1,200\,\text{feet AGL}$: This is the default altitude if no other markings are present on the chart. It is effectively "invisible."

• Visual Indicators on Sectional Charts:

  1. Dashed Magenta: Like the "stakes in the ground" metaphor, a dashed magenta line signifies the airspace is staked to the surface. Everything within the lateral boundary of this dashed line is Class E starting at ground level.

  2. Shaded/Soft Magenta: This signifies "softened rules." The floor of the airspace is raised to $700\,\text{feet AGL}$. Below this $700\,\text{foot}$ shelf, the airspace is typically Class G.

  3. No Designation: In areas with no blue or magenta lines, Class E starts at $1,200\,\text{feet AGL}$.

• Vertical Extension: Class E airspace typically extends from its floor up to, but not including, $18,000\,\text{feet MSL}$, which is where Class A airspace begins.

• Uncontrolled Airports: Class E airports are often uncontrolled, represented by magenta runways and magenta text on the chart (instead of blue). They lack a Control Tower (CT) designation in their airport information block.

Class G (Class Golf) Airspace

• Characterization: Class G is often called "Good" or "Great" by drone operators because permission/authorization to operate is not required. One can fly within regulations up to $400\,\text{feet}$ without ATC approval.

• The "Ground" Airspace: Similar to Class D, Class G always starts at the surface/ground level.

• Boundaries: Class G exists wherever other airspaces do not. It typically extends from the surface up to the floor of the overlying Class E airspace ($700\,\text{feet AGL}$ or $1,200\,\text{feet AGL}$).

• Prevalence: Class G accounts for approximately $85\%$ of the airspace in the United States, particularly in rural areas like Central Kansas.

• Traffic Types: In Class G, expect general aviation aircraft such as single-engine or multi-engine piston planes (e.g., Cessna 172s, Bonanzas, Archers, and crop dusters).

Navigational Practice and Discussion

• Pocatello Regional Airport Case Study:

  • Control Tower Frequency: $119.1\,\text{MHz}$.

  • Longest Runway: $9,000\,\text{feet}$.

  • Field Elevation: $4,452\,\text{feet MSL}$.

  • Airspace: Class D starts at the surface and goes up to a ceiling of $7,000\,\text{feet MSL}$.

• Bismarck Practice: The intern-stake metaphor is used here. Imagine an intern with a wagon of blue stakes; each stake hammered into the ground corresponds to a dash in the blue ring, signifying Class D down to the surface.

• Scenario: Mud Lake Exercise:

  • Location: Near Wilder Airport, surrounded by faded magenta.

  • Question: What airspace are you in for takeoff/landing?

  • Answer: Class G. The faded magenta means Class E starts at $700\,\text{feet AGL}$, so the space from the surface to $699\,\text{feet}$ is Class G.

• Scenario: Joe Foss Field Transmission Lines:

  • Location: Investigating power lines within a blue dashed circle.

  • Airspace: Class D. It starts at the surface and extends to the box ceiling (e.g., $3,900\,\text{feet MSL}$).

• Scenario: Aero Country (T31) Identification:

  • Location: Near Dallas-Fort Worth ($DFW$).

  • Observed: Under a Class B shelf (starting at $4,000\,\text{feet MSL}$), no dashed blue, no dashed magenta.

  • Answer: Taking off from the ground here puts the operator in Class G. Class E does not start until $1,200\,\text{feet AGL}$ in this unmarked area.

Military Training Routes (MTRs)

• Visual Representation: MTRs are depicted as gray lines on sectional charts.

• Naming Convention: They are prefixed with either IR (Instrument Rules) or VR (Visual Rules) followed by a number.

• The Four-Digit Rule: This is a critical detail for drone pilots:

  • Four-number identifiers (e.g., $VR1154$) indicate the route includes segments below $1,500\,\text{feet AGL}$.

  • Drone operators (who fly below $400\,\text{feet AGL}$) are at high risk of encountering military traffic in these areas.

  • Three-number identifiers indicate the route is primarily above $1,500\,\text{feet AGL}$.

Temporary Flight Restrictions (TFRs)

• Significance: TFRs are the primary cause of pilot license suspensions. They are flexible, temporary, and must be approved by the FAA.

• Common Causes for TFRs:

  • Sporting Events: Outdoor venues with a capacity of $30,000$ people or more receive an automatic TFR. It is active from one hour before the event until one hour after the event (e.g., K-State stadium games with $50,000+$ people).

  • Natural Disasters: Wildfires, floods, tornadoes, and hurricanes.

  • VIP Movements: Presidential or high-profile candidate visits.

  • Air Shows.

Special Use Airspace

• Restricted Areas (No-Go Areas):

  • Indicated by blue zipper/comb lines with "fingers" pointing inward to the area.

  • Marked with an "R" followed by numbers (e.g., $R\text{-}5107B$).

  • These areas often involve hazardous activities like dropping bombs or live-fire exercises. Fly here only with explicit permission.

• Military Operating Areas (MOAs) (Go Areas):

  • Indicated by magenta zipper/comb lines.

  • Drones can fly here without authorization, but pilots must exercise extreme caution ("Be on the lookout"). Military jets may be present, though usually at higher altitudes.

• Terminal Radar Service Area (TRSA):

  • Visual: Gray rings that resemble Class B or C tiers.

  • Definition: A TRSA is not an airspace classification. It is a service area where the airport has radar facilities capable of providing significant navigation and guidance help to pilots.

  • Example: Kalamazoo. It features fractions (e.g., $\frac{60}{40}$) indicating where radar coverage exists.