High Altitude and Cold Weather Flights
and Maximum (Terminal) Velocity Descent

Objective

• To familiarize the student with high altitude/cold weather balloon flight and Maximum Velocity (Terminal) Descent

Elements

• Preparation for high altitude
• Preparations for cold weather
• Observing effects on balloon performance
• Maximum velocity descent

Equipment

• Airworthy balloon
• Cold weather clothing appropriate to temperatures aloft

Instructor’s Actions

• Pre-flight discussion for high altitude flight to include maximum altitude, airspace considerations, altimeter setting, wind and temperature aloft forecast, load calculation, density altitude, pilot oxygen requirements, burner oxygen starvation, short blasts best, preparation to relight pilot light
• Pre-flight discussion for cold weather operation to include clothing (especially feet), survival gear, effect of temperature on batteries, advantages and disadvantages of heating fuel versus nitrogen charging, possibility of an 0-ring leak
• Pre-flight discussion for observing effects of high altitude on performance to include ascent at constant rate, record ambient temperature to verify if lapse rate is standard, record envelope temperature at 500' intervals, calculate time for ascent and descent
• Pre-flight discussion on Maximum Velocity Descent (MVD) Terminal Speed to include dangers associated with and associated remedial actions, calculate altitude needed to round out MVD, observe rate of descent and temperature during MVD
  • Terminal Speed - That speed at which the upward resisting force of the air equals the weight, so that the resulting force is zero, and no further acceleration is experienced.

Student’s Actions

Perform each maneuver as directed

• High altitude operation
• Knowledge of airspace requirements
  • Setting the altimeter
  • Interpreting wind and temperature aloft forecast
  • Demonstrate knowledge of weight calculation
  • Demonstrate effect of density altitude
  • Knowledge of pilot oxygen requirements
  • Knowledge of oxygen starvation of burner
  • Knowledge of high altitude blast valve operation
  • Demonstrate relighting pilot light on surface
• Cold weather operation
  • Dress for temperature at altitude
  • Knowledge of the effect of temperature on batteries and propane
  • Knowledge of advantages and disadvantages of heating fuel versus nitrogen charging
  • Simulates action if 0-ring leaks on burner or on tank valve
• Effect of high altitude on performance
  • Ascends to 2000 feet AGL (private) at constant rate ± 100 fpm or ascends to 3000 feet AGL (commercial) at a constant rate ±50 fpm without over temping envelope
  • Record ambient temperature at 500' intervals
  • Record envelope temperature at 500' intervals
  • Calculate lapse rate and compare to standard rate
  • Calculate time for ascent and descent
• Maximum (Terminal) Velocity Descent (Commercial Requirement)
  • Descend and recover from a MVD
  • Record envelope temperature at equilibrium
  • Record envelope temperature during MVD
  • Measure altitude needed to round out from MVD
  • Does not use vent during MVD
  • React to wind shears with additional heat
  • Use burner to open throat if closing due to wind shear or excess cooling

Completion Standards

The student should be able to demonstrate his/her ability to establish and maintain a constant rate of climb from launch to planned altitude while maintaining envelope temperature.  Demonstrate knowledge of airspace, wind and temperature aloft forecast, weight calculation, effects of cold temperature and high altitude performance and the dangers associated with MVD.  Demonstrates a MVD and maintains safe operation during the descent and properly rounds out from the descent.