Mission Aircrew Course High Altitude and Terrain Considerations (APR 2010)

1. Mission Aircrew CourseHigh Altitude and Terrain Considerations(APR 2010)

2. Aircrew Tasks • P-2011 DISCUSS THE EFFECTS OF DENSITY ALTITUDE ON AIRCRAFT PERFORMANCE (O) • P-2024 DISCUSS STRATEGIES TO COMBAT HIGH ALTITUDE EFFECTS (S)

3. Objectives • Discuss the symptoms and dangers of dehydration, and strategies used to combat its effects. • Discuss the symptoms and dangers of ear block, sinus block and hypoxia, and strategies used to combat their effects.

4. Objectives • Review the effects of high altitude on aircraft performance • Concerning atmospheric pressure: • State the pressure at sea level, and describe how to compensate for ‘other-than-sea level pressures’ when setting the altimeter • Discuss the three factors that affect the density of an air mass. • Define density altitude • State the phases of flight affected by a decrease in atmospheric pressure, and how aircraft performance is affected. • Discuss strategies to compensate for high DA during searches. • Discuss mountainous terrain precautions and strategies.

5. Human Performance: Dehydration • The loss of water through the skin, lungs and kidneys never ceases • Loss increases as the humidity drops with increasing altitude • Symptoms are dryness of the tissues and resulting irritation of the eyes, nose and throat • Minimize intake of coffee, tea, cola or cocoa since they contain caffeine and other chemicals • Prevention Strategies • Drink plenty of hydrating fluids – WATER! • Increase air flow (vents and windows) • If the search objective allows, reduce temperature by climbing to higher altitude

6. Other Effects of Altitude • Ear Block • Congestion around the Eustachian tube makes pressure equalization difficult • Can produce severe pain and a loss of hearing that can last from several hours to several days (can rupture eardrum) • Sinus Block • Sinus congestion makes pressure equalization difficult, particularly during descent • Can produce severe pain • Hypoxia • Normally not a concern for non-mountainous CAP operations (usually below 12,000 MSL) • Can have loss of night vision as low as 5,000 feet • Body has no built-in warning system against hypoxia • Everyone ’s symptoms are different • Onset altitude will vary depending upon individual

7. Prevention Strategies • Ear Block • Yawn, swallow, tense muscles in throat • Valsalva maneuver • Sinus Block • Don’t fly if you’re not well • Medication usually not effective and has side effects • Hypoxia • Avoid smoking, alcohol and depressants • Supplemental oxygen

8. Atmospheric Pressure • A barometer is used to register changes in pressure; measured in inches of mercury • Standard sea-level pressure and temperature: • 29.92 inches of mercury • 59 degrees F (15 degrees C) • A change of 1000 feet in elevation makes a change of about one inch • To correct for local elevation, set altimeter to latest reading (ATIS/AWOS/ASOS/FSS) or enter field elevation

9. Density Altitude • Three factors: • Pressure • Temperature • Humidity • Altitude and pressure combined to determine pressure altitude • Add non-standard temperature to get density altitude • Remember: Drag, lift, power available and true airspeed are all affected by density altitude

10. TAS vs. DA

11. Density Altitude

12. Flight Computer • Circular slide rule • Density altitude • Nautical to statute miles • True airspeed • Other stuff

13. Aircraft Performance • Density altitude and aircraft weight have a tremendous effect on aircraft performance • Both must be accurately calculated, especially for mountain flying missions

14. Pressure vs. Performance • As altitude increases pressure decreases; this decrease can have a pronounced effect on flight: • Engine (hp) and prop are less efficient • Take off distance, climb rate, and landing distance effected • Take off distance almost doubles with a 5000 foot elevation increase • Rate of climb slows with higher elevation • Landing distance increases with higher elevation • Higher Humidity, Heat or Height result in reduced aircraft performance

15. DA & ROC

16. Reduced Performance

17. Strategies • Don’t fly at high elevation during the hottest part of the day • Carefully calculate DA and weight • Reduce load: • Less fuel • Crew of three instead of four • Less baggage • Remember “High to Low, Look out Below” (update altimeter setting hourly) • If you fly in the mountains, take the Mountain Fury Course

18. Flight Near Mountainous Terrain • Crews must be constantly careful that the search never takes them over terrain that rises faster than the airplane can climb. Narrow valleys or canyons that have rising floors must be avoided, unless the aircraft can be flown from the end of higher elevation to the lower end, or the pilot is certain that the aircraft can climb faster than the terrain rises. Careful chart study by the crew prior to flight will help identify this dangerous terrain. • If you fly in the mountains, take the Mountain Fury Course

19. Flight Near Mountainous Terrain

20. Flight Near Mountainous Terrain

21. Flight Near Mountainous Terrain

22. Questions?