Instrument Flight Rules and Air Law
The regulatory skeleton
Instrument flight is governed by a layered structure: ICAO Annex 2 (Rules of the Air) and Annex 6 (Operation of Aircraft) set the international baseline, while each State's national regulations implement them with local differences. Candidates must know the concepts of IFR flight clearance, the pilot-in-command's responsibility for terrain and obstacle clearance even when cleared, the meaning of "clearance void if not airborne by", and the distinction between a clearance and an instruction. Know the categories of airspace and what they permit for IFR, the standard separation minima applied by ATC, and the rules for position reporting, alternate aerodrome requirements, and minimum fuel.
Traps
Questions frequently test the difference between a clearance limit and an approach clearance, and whether an IFR flight plan must be cancelled or closed. Another common trap is the assumption that a clearance relieves the pilot of responsibility for obstacle clearance; it never does. Watch for questions on the validity periods of medical certificates and recency of instrument experience, and on the meanings of "hold for release" and "expect further clearance".
Worked example
A clearance reads: "Cleared to the ABC VOR, maintain 5,000 ft, expect 7,000 ft after 10 minutes." The clearance limit is the ABC VOR, not the destination; if you reach it without further clearance, you must hold. The altitude change is an expectation, not an authorization.
Rule of thumb
A clearance is a limit plus a route plus an altitude plus any instructions; if any element is missing, ask before you proceed.