Under standard ICAO flight planning rules, baseline contingency fuel is calculated as a percentage of the planned trip fuel.

### Why this is right The stated contingency is exactly 5 percent of trip fuel. It is calculated from trip fuel, not from the total fuel requirement or from alternate fuel. ### The concept A percentage allowance must be applied to its stated base. Here, multiply trip fuel by 0.05 to obtain contingency fuel. The result is then added to trip fuel, alternate fuel, and final reserve when forming the total. ### Worked numbers - **Given**: contingency rate 5 percent of trip fuel. - **Find**: the contingency component. - **Formula**: contingency = 0.05 × trip fuel. - **Check**: the contingency amount is 5 parts for every 100 parts of trip fuel. ### Terms - **Trip fuel**: Fuel planned for the route. - **Contingency fuel**: The 5 percent allowance based on trip fuel. ### Remember Apply 5 percent to trip fuel only.