What is the flight time available at 18,000 ft with a temperature of -1 °C, power at 2,200 RPM, and a fuel load of 344 lb?

To determine the flight time available, you start by calculating the fuel consumption based on the provided parameters, including altitude, temperature, engine RPM, and fuel load.

At 18,000 ft with a temperature of -1 °C, the aircraft's engine performance is affected by the reduced air density at high altitudes, which can lead to changes in fuel consumption. For a given power setting of 2,200 RPM, you would use the specific fuel consumption figures for the aircraft's engine to identify how much fuel is consumed per hour under those conditions.

Assuming you have data for fuel consumption at the given RPM and altitude, you would calculate the total flight time by dividing the total fuel load by the fuel consumption rate. For example, if the fuel consumption were determined to be around 58 lbs per hour at the specified RPM and altitude, you could then divide the total available fuel (344 lbs) by this rate (58 lbs per hour). This calculation would yield approximately 5.93 hours of flight time, which translates to 5 hours and 59 minutes.

Thus, by undertaking these calculations, you arrive at the correct flight time of 5 hours and 59 minutes, which matches the choice provided.