★ PTS mapping: This lesson aligns to FAA-S-8081-20A (Nov 2023), Area of Operation I — Preflight Preparation (use the Lesson→Area map). It is a PTS, so items are Tasks/elements (no ACS K/R/S codes); read exact Task lettering and tolerances from the current published PTS.
Airspace from the surface up, and the Part 91 vs Part 135 framework an ATP is expected to know cold.
The NAS divides into controlled classes A, B, C, D, E and uncontrolled G, plus special-use airspace (prohibited, restricted, warning, MOA, alert, CFAs) and other areas (TFRs, national security areas). Each class carries its own entry requirement (clearance vs two-way comms vs none), equipment (transponder/ADS-B Out under §91.225/§91.215), and VFR weather minimums (the cloud-clearance and visibility matrix of §91.155).
| Class | Entry (VFR) | Equip / note |
|---|---|---|
| A (FL180–FL600) | IFR only, clearance required | No VFR; RVSM FL290–FL410 |
| B | ATC clearance to enter | Mode C/ADS-B Out; "cleared into Bravo" required |
| C | Two-way comms established | Mode C/ADS-B Out |
| D | Two-way comms established | Tower; revert to E/G when tower closed |
| E / G | None (G uncontrolled) | §91.155 minimums; helicopter special provisions apply |
Helicopters get specific relief in several places — notably the helicopter special VFR provisions and reduced visibility allowances when operating "clear of clouds" at safe speeds — but those are exceptions, not defaults, and must be applied exactly as written.
Helicopters have reduced VFR visibility/cloud-clearance provisions and special-VFR allowances — see 14 CFR 91.155 (including its helicopter notes) and 91.157; confirm verbatim against the current text. The table above is a summary and omits the helicopter-specific reductions.
Part 91 is the baseline "general operating and flight rules" that apply to nearly every flight. Part 135 adds the commuter and on-demand commercial framework — more restrictive weather minimums, required ops specs, an MEL, defined PIC qualifications and currency, and crew flight/duty/rest limits. The same helicopter and pilot can be flying under Part 91 one hour and Part 135 the next; what changes is the operational control, the rule set, and the margins. An ATP must know which regime governs the flight and the higher bar Part 135 imposes (e.g., IFR alternate and approach minimums, VFR weather/visibility floors).
Part 135 imposes flight-time and rest limits to manage fatigue (the structure differs for unscheduled on-demand vs scheduled operations, and for one- vs two-pilot crews). Part 91 has no equivalent hard duty limit, which paradoxically places more responsibility on the individual pilot's fatigue self-assessment. Either way, fatigue is treated as a flight-safety hazard, not a personal inconvenience.
If the operation is Part 135, confirm the applicable subpart's flight/duty/rest limits; if Part 91 only, those limits don't apply. Tailor the depth here to your operation — confirm whether students are being prepared for Part 91 operations only, or Part 135 as well.
An MEL (Minimum Equipment List) is an FAA-approved document letting an aircraft be dispatched with certain items inoperative under defined conditions; without an approved MEL, §91.213 governs inoperative equipment. Special VFR permits VFR operation within surface-based controlled airspace below normal minimums by ATC clearance — helicopters enjoy expanded SVFR privileges. RVSM (Reduced Vertical Separation Minimum, FL290–FL410) is largely an airplane environment but appears in the ATP knowledge base; helicopters rarely operate there, yet the concept and equipment/authorization requirements are fair game.
Curated reference clip — “Airspace Review Part 1 Helicopter Online Ground School” · Helicopter Online Ground School LLC (YouTube), verified via oEmbed. Embedded with the creator's player; we don't host or alter it.
✈️ Your test aircraft: the R-44 fill-in values cover its single-engine, piston, VFR figures, and it would not normally operate in Class A / RVSM airspace or under most Part 135 IFR rules. ATP-H practical tests are normally flown in a turbine and/or multi-engine, IFR-capable helicopter — use your actual test aircraft's data (systems/IFR/performance/start/runup as relevant) from its RFM/POH for items marked aircraft-specific, and confirm Part 135 applicability to your program.