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Private pilot · ACS PA.I.E · lesson pack

National Airspace System

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Why this one matters

Airspace exists to separate traffic and protect people on the ground. Busting a Class B shelf, wandering into a TFR, or pushing VFR minimums into cloud puts you where other airplanes and ATC don't expect you. Knowing the boundaries, the entry requirements and the weather minimums is how you fly predictably and safely around everyone else.

1 · Know these cold

  • •Class B: an ATC clearance ("cleared into the Class Bravo"), a two-way radio, a Mode C transponder and ADS-B Out; 3 statute miles and clear of clouds.(14 CFR 91.131, 91.155)
  • •Class C: establish two-way radio communication before entering, plus a Mode C transponder and ADS-B Out; 3 miles, 500 below, 1,000 above, 2,000 horizontal.(14 CFR 91.130, 91.155)
  • •Class D: establish two-way radio communication before entering; 3 miles, 500 below, 1,000 above, 2,000 horizontal.(14 CFR 91.129, 91.155)
  • •Class E below 10,000 MSL: 3 miles, 500/1,000/2,000. At or above 10,000 MSL: 5 miles, 1,000 below, 1,000 above, 1 mile horizontal.(14 CFR 91.155)
  • •Class G at or below 1,200 AGL by day: 1 mile and clear of clouds. At night: 3 miles, 500/1,000/2,000.(14 CFR 91.155)
  • •Speed (indicated): 250 knots below 10,000 MSL; 200 knots at or below 2,500 AGL within 4 nm of a Class C or D primary airport (not inside Class B, where 250 applies); and 200 knots in the airspace under a Class B shelf or in a VFR corridor through it.(14 CFR 91.117(a)-(c))
  • •Check TFRs and NOTAMs before every flight; prohibited areas are off-limits, restricted areas need permission.(14 CFR 91.103, 91.133, 91.137-91.145)

2 · The lesson

The classes and what they require
  • Class A: 18,000 feet MSL up to FL600. No VFR at all: an instrument-rated pilot on an IFR flight plan with an ATC clearance, a two-way radio, a Mode C transponder and ADS-B Out.(AIM chapter 3, Airspace; 14 CFR 91.135, 91.215, 91.225)
  • Class B generally extends from the surface to 10,000 feet MSL around the busiest airports, in individually tailored layers shaped to contain the instrument procedures.(AIM chapter 3, Airspace)
  • Class B: around the busiest airports, shaped like an upside-down wedding cake. Needs an ATC clearance, a two-way radio, a Mode C transponder and ADS-B Out. A private pilot may enter; student pilots need an endorsement, and some primary airports don't allow student operations.(14 CFR 91.131)
  • Mode C and ADS-B Out are also required within 30 nm of a Class B primary airport (the Mode C veil), in and above Class C up to 10,000 MSL, and in Class E at or above 10,000 MSL (except at or below 2,500 AGL).(14 CFR 91.215, 91.225)
  • Class C: typically a 5 nm core from the surface to 4,000 feet above the airport and a 10 nm shelf from 1,200 feet. The shelf's ceiling is also 4,000 feet above the airport. Around it is a procedural Outer Area, normally 20 nm, uncharted, where participation isn't required the same way. Charted Class B and C altitudes are MSL, even though the textbook describes them above the airport.(14 CFR 91.130; AIM 3-2-4)
  • Two-way communication for Class C and D: a reply using your call sign, even "[call sign], stand by", establishes it and you may enter, unless the reply tells you to remain outside ("[call sign], remain outside the Class Charlie and stand by"). A reply without your call sign ("aircraft calling Approach, stand by") does not establish it: stay out.(14 CFR 91.130(c), 91.129(c); AIM 3-2-4, 3-2-5)
  • Class D: around towered airports, typically up to 2,500 feet above the airport. Establish two-way communication before entering. Class D itself requires only the radio: no transponder or ADS-B Out (unless other rules, such as the Mode C veil, apply). When the tower closes, it usually becomes Class E or G; check the Chart Supplement.(14 CFR 91.129; AIM 3-2)
  • Class E: controlled airspace that isn't A, B, C or D. It may start at the surface, at 700 or 1,200 feet AGL, or at other altitudes. No communication is required for VFR.(AIM chapter 3, Airspace)
  • Class G: uncontrolled airspace below Class E.(AIM chapter 3, Airspace)
VFR weather minimums
  • Class B: 3 statute miles, clear of clouds.(14 CFR 91.155)
  • Class C, D and E below 10,000 MSL: 3 miles; 500 feet below, 1,000 above, 2,000 horizontal from clouds.(14 CFR 91.155)
  • Class E at or above 10,000 MSL: 5 miles; 1,000 below, 1,000 above, 1 mile horizontal.(14 CFR 91.155)
  • Class G at or below 1,200 AGL: day 1 mile, clear of clouds; night 3 miles, 500/1,000/2,000 (or 1 mile and clear of clouds in a traffic pattern within half a mile of the runway).(14 CFR 91.155)
  • Class G above 1,200 AGL below 10,000 MSL: day 1 mile, 500/1,000/2,000; night 3 miles, 500/1,000/2,000. Above 10,000 MSL: 5 miles, 1,000/1,000/1 mile.(14 CFR 91.155)
  • Two separate rules, except under special VFR (91.157): you may not fly under VFR beneath a ceiling of less than 1,000 feet anywhere within the lateral limits of a surface area of controlled airspace (91.155(c)); and you may not take off, land, or enter the traffic pattern in a Class B, C, D or E surface area unless the ground visibility there is at least 3 statute miles, or the flight visibility is if ground visibility isn't reported (91.155(d)).(14 CFR 91.155(c)-(d); 91.157)
Reading the chart
  • Class B: solid blue lines. Class C: solid magenta. Class D: dashed blue. Class E to the surface: dashed magenta.(FAA Aeronautical Chart User's Guide)
  • Class E starting at 700 feet AGL: the faded magenta edge (vignette). Starting at 1,200 feet AGL: the faded blue edge.(FAA Aeronautical Chart User's Guide)
  • Altitude labels like 80/40 in Class B or C mean a ceiling of 8,000 and a floor of 4,000 feet MSL.(FAA Aeronautical Chart User's Guide)
Special use airspace, TFRs and other areas
  • Prohibited areas: flight not allowed. Restricted areas: not allowed when active without permission from the controlling agency.(14 CFR 91.133; AIM 3-4)
  • Military operations areas (MOAs): VFR flight is allowed, but watch for fast military traffic and ask ATC whether they're active. Warning areas extend from 3 nm outward from the U.S. coast with activity that may be hazardous; the U.S. doesn't have sole jurisdiction, so no permission is needed, but use caution. Alert areas have a high volume of pilot training or unusual aerial activity: use caution. Controlled firing areas aren't charted, because the activity stops when an aircraft approaches. National security areas: you are asked to avoid them voluntarily, and flight may be temporarily prohibited.(AIM 3-4-1 to 3-4-8)
  • Other areas: a TRSA isn't an airspace class (its primary airport is Class D); VFR participation is voluntary and gives radar service. Military training routes: IR flown under IFR, VR under VFR; four-digit routes stay at or below 1,500 AGL, three-digit routes have a segment above it, and military aircraft may exceed 250 knots below 10,000 MSL, so cross them with vigilance and don't follow them. Also know ADIZ rules (a flight plan, a discrete code and two-way radio), parachute jump areas, and published VFR flyways and transition routes.(PHAK (FAA-H-8083-25C), Ch. 15; AIM 3-5)
  • Temporary flight restrictions (TFRs) cover VIP movements, stadiums, fires and other events. They're in the NOTAMs; check them before every flight.(14 CFR 91.137-91.145; AIM 3-5)
  • Special flight rules areas, like the Washington, DC SFRA, have their own rules and required training.(14 CFR Part 93; 91.161)
Special VFR
  • Special VFR lets you operate below VFR minimums within the surface area of controlled airspace, below 10,000 MSL, with an ATC clearance. You must ask for it; ATC doesn't offer it.(14 CFR 91.157)
  • You need at least 1 statute mile flight visibility and must stay clear of clouds. To take off or land, ground visibility must be at least 1 statute mile (flight visibility, if ground visibility isn't reported). Fixed-wing special VFR isn't allowed at the airports in Part 91, Appendix D, Section 3 (charted "NO SVFR").(14 CFR 91.157; Part 91, Appendix D)
  • At night (sunset to sunrise), special VFR requires the pilot to be instrument rated and current, and the airplane equipped for IFR under 91.205(d).(14 CFR 91.157(e))

Want it all on one page, with scenarios? Read the full lesson.

3 · Say it out loud

Answer each one out loud, then check yourself and mark how it went.

  1. Remember Recall it

    “What do you need to enter Class C airspace?”

  2. Understand Explain why

    “The controller answers your call with "Aircraft calling Approach, stand by." Can you enter Class C?”

  3. Apply Use it on a flight

    “You're VFR at 2,000 feet AGL in Class E, and clouds ahead are at about 2,400. Can you continue at this altitude?”

4 · Common mistakes

  • Treating "radar contact" as permission to enter Class B.

    Only "cleared into the Class Bravo" is a clearance.

    Instead: Wait for the explicit clearance.

  • Mixing up the cloud clearances.

    Class B is clear of clouds; C, D and E are 500 below, 1,000 above, 2,000 horizontal.

    Instead: Learn the table by class and altitude, and day versus night in Class G.

  • Skipping a TFR check on a short local flight.

    TFRs pop up for VIPs, fires and stadiums, sometimes the same day.

    Instead: Check NOTAMs and TFRs right before every flight.

5 · Quick check

Answer, then reveal. Flag anything you want to see again.

  1. 1. What are the VFR weather minimums in Class B?

  2. 2. What are the minimums in Class G below 1,200 AGL during the day?

  3. Scenario3. You call Approach and hear "[your call sign], remain outside the Class Charlie and stand by." Can you enter?

  4. 4. What is the speed limit below 2,500 AGL within 4 nm of a Class D primary airport?

  5. 5. What does a faded magenta edge on a sectional mean?

  6. Scenario6. At night, can a private pilot without an instrument rating get special VFR?

  7. 7. Within how many nautical miles of a Class B primary airport is a Mode C transponder required?

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Connect it

One situation that runs across this lesson and its neighbors in the same ACS area. Decide first, then check.

Connect it · Preflight Preparation

A July afternoon. You plan a 90 NM trip from a 2,800-foot runway at 1,500 feet elevation; it's 33 °C. The destination TAF has a TEMPO for thunderstorms starting about when you'd arrive.

How do the weather, the airplane's performance and your fuel plan change one another, and what do you decide? Decide, then see the worked answer

Work the density altitude first. Standard temperature at 1,500 feet is about 12 °C, so 33 °C is about ISA +21 °C and the density altitude is roughly 4,000 feet (more if the pressure is low). Enter the POH takeoff and climb charts at the actual pressure altitude and temperature, never the field elevation, and compare the ground roll, the distance over a 50-foot obstacle and the climb with the 2,800 feet and the obstacles, with a margin. If it's tight, cut payload and baggage first. Never cut fuel below trip fuel plus fuel to divert to an alternate plus the 91.151(a)(1) day VFR reserve of 30 minutes at normal cruise. After any load change, recompute the weight and balance and the CG, and check the landing distance at the destination too. The TEMPO puts thunderstorms over the destination at your arrival. Don't plan to beat the TEMPO window or to divert closely around cells: avoid thunderstorms with severe or intense radar echoes by at least 20 miles, never take off or land in the face of an approaching thunderstorm, and wait storms out on the ground. With thin performance margins and storms at the far end, the better answer is the cooler, calmer morning.

PHAK (FAA-H-8083-25C), Aircraft Performance and Weather Theory; AC 00-24C, Thunderstorms; 14 CFR 91.103, 91.151

Brings together: Weather Information · Cross-Country Flight Planning · Performance and Limitations

Teaching this? The instructor lesson plan →

Study aid, not FAA guidance. Sources: 14 CFR Part 91; AIM; Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C); FAA Aeronautical Chart User's Guide. Checked against current sources 2026-11-12.