Flight Planning and Monitoring under IFR
IFR flight planning is a chain of calculations that must be internally consistent: route, level, fuel, alternate, and performance. Candidates must know the fuel policy structure (taxi, trip, contingency, alternate, final reserve, and any extra), the requirement for an alternate destination and the weather criteria that remove that requirement, and the take-off and landing performance minima.
Concepts to master
- Fuel: trip fuel, contingency (typically a percentage of trip fuel), alternate fuel, final reserve (expressed in minutes of holding), and additional fuel for any specific risk.
- Alternate: when one is required, and the weather minima (ceiling and visibility) that must be forecast at the destination to allow a flight without an alternate.
- Mass and balance: the effect of load on hover performance and on the IFR climb gradient.
- Monitoring: in-flight fuel checks, the decision point, and the point of no return for a helicopter on a long transit.
- Flight plan content: route, levels, speeds, endurance, and the alternate entry.
Common traps
Questions quote a contingency as a percentage and expect a figure in minutes or kilograms. Another trap is assuming an alternate is always required, or never required, rather than testing the forecast conditions against the minima.
Rule of thumb
Build the fuel ladder in order and check the total: taxi + trip + contingency + alternate + final reserve + extra. If the sum exceeds the usable fuel, the plan is invalid.
Worked example
Trip fuel 400 kg, contingency 5% (20 kg), alternate 80 kg, final reserve 30 minutes at 300 kg/h (150 kg). Total without extra: 400 + 20 + 80 + 150 = 650 kg. Usable fuel of 700 kg leaves only 50 kg of margin.