✈️ Aviation Brief — Issue #61
Weekly insights for student pilots and the instructors who train them.
THIS WEEK'S TOPIC
IA.IV.A — Enroute Airspace (Instrument Rating ACS)
**1. ACS STANDARDS SUMMARY**
The Instrument Rating ACS (IA.IV.A) requires you to identify and explain the operating rules, pilot certification, and aircraft equipment needed for each class of airspace you’ll fly through en route. You must locate and interpret airspace on sectional, en route low, and VFR terminal area charts, including Class A, B, C, D, E, and G, plus special-use airspace such as MOAs, restricted areas, and TFRs. The examiner expects you to describe when an IFR clearance is required, what ATC services are available, and how to transition between airspace classes without violating rules.
**2. THREE COMMON STUDENT MISTAKES**
- Assuming “controlled airspace” automatically means you need an ATC clearance; many students forget that Class E below 10,000 ft often allows IFR without a clearance if they remain outside clouds.
- Misreading the floor of Class E on en route charts (e.g., treating a 700-ft AGL “fuzzy” border the same as a hard 1,200-ft AGL border) and planning an instrument departure or arrival without adequate obstacle clearance.
- Overlooking the vertical limits of MOAs and restricted areas when filing a direct route, resulting in either an uncomfortable reroute or an airspace violation.
**3. CFI PRO TIP**
Have the student draw a simple cross-country on the actual en route chart first, then mark every airspace boundary they will cross. Ask them to write the exact rule that changes at each line (cloud clearance, radio requirement, IFR clearance needed, etc.). This single exercise turns abstract chart markings into a concrete mental model they can use on checkrides and in actual IMC.
**4. SAFETY SPOTLIGHT**
NTSB accident data and ASRS reports continue to show IFR pilots entering active MOAs or restricted areas because they accepted a direct routing without confirming the airspace was cold. In several recent cases the controller was unaware the pilot lacked current SUA status, producing near mid-airs with military traffic or forced rapid climbs and descents through IMC.
**5. DID YOU KNOW**
Even in Class E airspace, you are not required to be on an IFR flight plan if you can stay in VMC and meet the basic cloud-clearance and visibility rules—yet most instrument students are surprised to learn they can legally cancel IFR and continue VFR in the same airspace if conditions permit.
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