Flight Planning and Instrument Procedures
Planning for IFR
Flight planning for IFR combines fuel, weather, alternates, and the structure of the departure, en-route, and arrival phases. Candidates must understand the standard instrument departure (SID) and standard arrival (STAR) design logic, including obstacle departure procedures, climb gradients expressed as percentages or feet per nautical mile, and the meaning of "runway heading" versus "runway track". Know how to compute a required climb gradient from a charted feet-per-nautical-mile value and how ground speed changes that requirement.
Traps
A frequent trap is confusing a minimum climb gradient with a minimum rate of climb: gradient is distance-based and must be converted using ground speed. Another is assuming a SID guarantees terrain clearance everywhere; the charted procedure does so only within its defined lateral and vertical limits. Questions also probe alternate selection when the destination has no instrument approach, fuel reserve calculations, and the difference between a routing that is "cleared as filed" and one that requires ATC amendment.
Worked example
A SID requires 300 ft/NM to 5,000 ft. At 120 kt ground speed, that is 2 NM per minute, so the required rate is 300 x 2 = 600 ft/min. At 180 kt ground speed (3 NM/min) the same gradient demands 900 ft/min.
Rule of thumb
Required rate of climb (ft/min) = gradient (ft/NM) x ground speed (NM/min). Always check whether the question gives ground speed, true airspeed, or indicated airspeed.