AI.III.C.K3aFAA-S-ACS-25 · Nov 2023Knowledge
a. Atmospheric composition and stability
Meteorology applicable to the departure, en route, alternate, and destination under visual flight rules (VFR) in Visual Meteorological Conditions (VMC), including expected climate and hazardous conditions such as: a. Atmospheric composition and stability
Bottom line
VMC means visibility, distance from cloud, and ceiling meet or exceed the minimums specified for VFR. Continued VFR flight from VMC into marginal VMC and IMC is a factor contributing to loss of control in-flight (LOC-I).
Key numbers
| Number | What it means |
|---|---|
| 15 to 20 minutes old by the time data sets are assembled and displayed in a cockpit | NEXRAD age |
| 6 hours or more before departure | Outlook window |
| significant changes expected within 1 hour before and after the ETA | Destination forecast |
FAA references
- PHAK Glossary (p. G-33) — FAA-H-8083-25C (2023)
- AFH ch. 5, Human Factors (p. 5-2) — FAA-H-8083-3C
- AC 91-92, paras. 7.6, 7.7 — AC No: 91-92
- AWH ch. 3 (p. 3-3) — FAA-H-8083-28A
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