6.4 Flight Rules, Regulations, and Airspace

6.4 Flight Rules, Regulations, and Airspace

The Aviation and Nautical Information Test (ANIT) is described by the Navy as a knowledge test — of all the ASTB-E subtests, it is the one whose score improves most from study. A large share of that knowledge is flight rules, regulations, and airspace, the framework that governs how and where aircraft may legally operate. Because these facts are memorizable, they are among the highest-yield ANIT topics for a candidate with limited aviation background, so treat this section as pure point-scoring memorization rather than reasoning.

Visual Flight Rules vs. Instrument Flight Rules

Every flight operates under one of two rule sets:

• Visual Flight Rules (VFR): The pilot navigates by outside visual reference and is responsible for seeing and avoiding other traffic. VFR requires visual meteorological conditions (VMC) — minimum visibility and distance from clouds that vary by airspace class.
• Instrument Flight Rules (IFR): The pilot flies by reference to cockpit instruments under air traffic control (ATC) clearance and separation. IFR is required in instrument meteorological conditions (IMC) — weather below VFR minimums — and always in Class A airspace.

The key exam distinction: VFR = see-and-avoid in good weather; IFR = instrument reference under ATC control, mandatory in low visibility or high-altitude airspace.

Classes of Airspace

U.S. airspace is layered into controlled classes (A, B, C, D, E) and uncontrolled Class G. A common memory aid pictures an upside-down wedding cake for the busy classes around major airports, with wider shelves stacked above a small surface core.

In Class A, altitudes are stated as flight levels (FL200 = 20,000 ft pressure altitude) and every aircraft sets a standard altimeter of 29.92 inches of mercury so vertical separation stays consistent despite local pressure changes.

VFR Weather Minimums

Because VFR relies on "see and avoid," the regulations set minimum visibility and cloud-clearance values that rise with speed and altitude. The common low-altitude case (below 10,000 ft MSL in Class C, D, or E) is the "3-152" rule: 3 statute miles of flight visibility and clearance of 500 ft below, 1,000 ft above, and 2,000 ft horizontally from clouds. Class B relaxes cloud clearance to simply remain clear of clouds with 3 miles visibility, while above 10,000 ft the requirement rises to 5 statute miles and 1,000 ft above / 1,000 ft below / 1 statute mile horizontal cloud clearance. Knowing that VFR visibility is measured in statute miles — not nautical miles — is a frequent distractor on the ANIT.

Right-of-Way Rules

When aircraft converge, regulations (14 CFR 91.113) assign priority to the aircraft that is least able to maneuver:

1. An aircraft in distress has right of way over all others.
2. Among the rest, priority runs balloon → glider → airship → powered aircraft, and any aircraft towing or refueling has priority over ordinary powered aircraft.
3. When two aircraft of the same category converge, the one on the right has the right of way.
4. Aircraft approaching head-on each alter course to the right.
5. An aircraft being overtaken has the right of way; the overtaking aircraft passes on the right.
6. Aircraft on final approach or landing have right of way over traffic in flight or on the surface, and when two are approaching to land, the one at the lower altitude has priority.

The Airport Traffic Pattern

Near an airport, aircraft fly a standard rectangular traffic pattern, normally with left-hand turns. The named legs, in order, are upwind, crosswind, downwind, base, and final. Aircraft generally take off and land into the wind to reduce ground speed and shorten the runway distance required. Knowing the leg names and the standard left-turn convention is a frequent ANIT item.

Hemispheric Cruising Altitudes

Above 3,000 ft AGL, VFR aircraft in level cruise obey the hemispheric rule, which keeps opposing traffic vertically separated by course. On a magnetic course of 0°–179° (generally eastbound) the aircraft flies an odd thousand plus 500 ft (3,500; 5,500; 7,500). On a magnetic course of 180°–359° (generally westbound) it flies an even thousand plus 500 ft (4,500; 6,500; 8,500). The memory hook is "east is odd, west is even, then add 500," and the rule is keyed to magnetic course over the ground, not the aircraft's heading.

Regulatory Framework and Documents

Civil flight in the United States is governed by the Federal Aviation Regulations (FARs), published by the Federal Aviation Administration (FAA). Two ideas recur on the ANIT:

• Altimeter and altitude terms. MSL (mean sea level) is height above sea level; AGL (above ground level) is height above the terrain directly below. Airspace floors and ceilings such as "18,000 ft MSL" are always referenced to sea level.
• Sectional charts and markings. VFR pilots navigate with sectional charts that depict airspace boundaries, terrain, and obstacles, and they read runway numbers as the runway's magnetic heading divided by ten (Runway 09 points roughly 090°/east).

Position Lights

A classic knowledge item is aircraft navigation (position) lights: a red light marks the left (port) wingtip, a green light marks the right (starboard) wingtip, and a white light marks the tail. At night these let one pilot judge another aircraft's direction of travel — seeing red on the left and green on the right means the other aircraft is heading toward you.

Because this material is pure knowledge, build a small fact sheet — VFR/IFR, the six airspace classes, the 3-152 weather minimums, right-of-way order, the five pattern legs, the hemispheric rule, the red-left/green-right light rule, and MSL vs. AGL — and drill it until recall is automatic. These are among the easiest ANIT points to lock in with a few study sessions.