Mission Aircrew Course High Altitude and Terrain Considerations

Aircrew Tasks P-2011 DISCUSS THE EFFECTS OF DENSITY ALTITUDE ON AIRCRAFT PERFORMANCE (O)

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.

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 Demonstrate knowledge of atmospheric pressure: state the pressure at sea level, and describe how to compensate for ‘other-than-sea-level pressures’ when setting the altimeter.

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 Discuss the three factors that affect the density of an air mass; Define density altitude, and compute density altitude for a given situation using a chart and a flight calculator.

TAS vs. DA

Density Altitude Compute density altitude for a given situation using a chart

Flight Computer Density altitude Nautical to statute miles Circular slide rule Density altitude Nautical to statute miles True airspeed Other stuff Compute density altitude for a given situation using a flight computer

Aircraft Performance Density altitude and aircraft weight have a tremendous effect on aircraft performance Both must be accurately calculated, especially for mountain flying missions State the phases of flight affected by a decrease in atmospheric pressure, and how aircraft performance is

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

DA & ROC

Reduced Performance

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 Discuss strategies to compensate for high DA during searches. Briefly discuss “High to Low, Look out Below”

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 Discuss mountainous terrain precautions and strategies. Approach ridges at a 45 degree angle. Cross at least 2,000 ft. above.

Flight Near Mountainous Terrain Discuss mountainous terrain precautions and strategies. Approach ridges at a 45 degree angle. Cross at least 2,000 ft. above.

Flight Near Mountainous Terrain Enter terrain from above and always have an escape route in mind.

Flight Near Mountainous Terrain Take the Mountain Fury course.

Questions? From 101T-MS Classroom training covering the applicable material outlined below is required prior to the issuance of a 101T for the Observer Specialty Visual Search Patterns and Procedures Electronic Search Patterns and Procedures Chart Reading / CAP Grid System Search Coverage Navigation and Position Determination Air Crew Coordination Weather High Altitude and Terrain Considerations Coordination with Ground Teams Flightline Operations Communications Procedures Flight Plans and Mission Forms Reimbursement Procedures State/Local Agreements Survival and First Aid Procedures Safety Transport Mission Procedures Scanning Techniques and Sighting Characteristics