Air Space Regulations

CFRs and Regulations for Aviation Airspace

The Federal Aviation Regulations (FARs), which are found in Title 14 of the Code of Federal Regulations (14 CFR), govern all aviation activities in the United States. The most relevant parts for pilots are generally Part 61 (Certification) and Part 91 (General Operating and Flight Rules).

Airspace	Regulating CFR & Chapter
Class A	14 CFR Part 91, Subpart B, §91.135
Class B	14 CFR Part 91, Subpart B, §91.131 This regulation covers general operating rules for Class B airspace, including the need for a specific ATC clearance. 14 CFR Part 61, §61.95 specifies the requirements for student pilots operating in this airspace.
Class C	14 CFR Part 91, Subpart B, §91.130
Class D	14 CFR Part 91, Subpart B, §91.129
Class E	14 CFR Part 91, Subpart B, §91.127 General operating rules for Class E airspace. §91.215 and §91.225 for transponders and ADS-B, respectively.
Class G	14 CFR Part 91, Subpart B, §91.126

For flights >10,000 MSL to <18,000 MSL

12,500 feet MSL: For flights above this altitude up to and including 14,000 feet, the flight crew must use supplemental oxygen for any portion of the flight lasting more than 30 minutes.

14,000 feet MSL: Above this altitude, the flight crew must use supplemental oxygen for the entire flight time.

15,000 feet MSL: Above this altitude, all occupants of the aircraft (passengers and crew) must be provided with supplemental oxygen.

Flights below <10,000 MSL must be <250 knots

Flights under Class B airspace <200 knots

Mode C Transponder and ADS-B Out are required:
- Above 10,000′ MSL (excluding airspace below 2,500′ AGL)
- Within 30 NM of Class B airports (Mode C veil)
- In and above Class C airspace
Class E airspace by itself does not require Mode C or ADS-B Out below 10,000′ MSL, unless you’re in one of the areas listed above.

VFR Airspace Entry and Operating Requirements
Airspace Class	Required Equipment (VFR)	Required Procedures (Before Entry)	Phraseology (Initial Contact)
Class A FL180 – FL600	IFR equipped (two-way radio, Mode C/S, ADS-B Out, IFR navigation)	Must be IFR flight. A pilot may not operate VFR in Class A. 5 SM, 1,000↑ 1,000↓ 1 SM↔	N/A (IFR procedures apply)
Class B Ceiling FL010	Two-way radio, Mode C/S Transponder, ADS-B Out	Must receive explicit ATC Clearance to enter. Two-way communication must be established. 3 SM – Clear of Clouds	“[Facility] Approach, [Aircraft ID], [Position], [Altitude], Request Class Bravo clearance.”
Class C Ceiling 4000 AGL	Two-way radio, Mode C/S Transponder, ADS-B Out	Must establish two-way communication with ATC. (Controller must respond with your full callsign). 3 SM, 1,000↑ 500↓ 2,000↔	“[Facility] Approach, [Aircraft ID], [Position], [Altitude], [ATIS ID], Inbound.”
Class D Ceiling 2500 AGL	Two-way radio	Must establish two-way communication with ATC. (Controller must respond with your full callsign). 3 SM, 1,000↑ 500↓ 2,000↔	“[Facility] Tower, [Aircraft ID], [Position], [Altitude], [ATIS ID], Inbound.”
Class E Ceiling FL018	None (Basic VFR equipment only) >FL600 Two-way radio, Mode C/S Transponder, ADS-B Out, Pressurized Cabin (Pressurized Flight Suit)	None required. No clearance or contact is mandatory. >10,000′ 5 SM, 1,000↑ 1,000↓ 1 SM↔ <10,000′ 3 SM, 1,000↑ 500↓ 2,000↔	N/A (Contact optional for advisories)
Class G 12oo AGL Faded Magenta reduces to 750 AGL	None (Basic VFR equipment only)	None required. No clearance or contact is mandatory. Night 3 SM, 1,000↑ 500↓ 2,000↔ Day 1 SM, 1,000↑ 500↓ 2,000↔ <1200 AGL 1 SM Clear of Clouds	N/A (Contact optional for advisories)

$\mathbf{12,500\text{ feet MSL}}$ to $\mathbf{14,000\text{ feet MSL}}$ : Required for flight crew after more than 30 minutes at these altitudes.
$\mathbf{14,000\text{ feet MSL}}$ and Above: Required for flight crew for the entire duration of the flight at these altitudes.
$\mathbf{15,000\text{ feet MSL}}$ and Above: Required for all occupants (crew and passengers) for the entire duration of the flight at these altitudes.
Flight Safety: Pressurized Cabins of <8,000 feet MSL are needed, not required, at or above FL018