Figure 16-17.  Establishing a wind correction angle that counteracts wind drift and maintains the desired course.  Before a cross-country flight, a pilot should make common  calculations for time, speed, and distance, and the amount  of fuel required.  Frequently, it is necessary to convert minutes into equivalent  hours when solving speed, time, and distance problems. To  convert minutes to hours, divide by 60 (60 minutes = 1 hour).  Thus, 30 minutes is 30/60 = 0.5 hour. To convert hours to  minutes, multiply by 60. Thus, 0.75 hour equals 0.75  ×  60  = 45 minutes.  To find the time (T) in flight, divide the distance (D) by the  GS. The time to fly 210 NM at a GS of 140 knots is 210 ÷  140 or 1.5 hours. (The 0.5 hour multiplied by 60 minutes  equals 30 minutes.) Answer: 1:30.  To find the distance flown in a given time, multiply GS by  time. The distance flown in 1 hour 45 minutes at a GS of 120  knots is 120  × 1.75 or 210 NM.  To find the GS, divide the distance flown by the time  required. If an aircraft flies 270 NM in 3 hours, the GS is  270 ÷ 3 = 90 knots.  Another conversion is that of changing knots to miles per hour  (mph). The aviation industry is using knots more frequently  than mph, but is important to understand the conversion for  those that use mph when working with speed problems. The  NWS reports both surface winds and winds aloft in knots.  However, airspeed indicators in some aircraft are calibrated  in mph (although many are now calibrated in both mph and  This standard industry convention yields a pounds-of-fuel­ per-hour value which, when divided into the nautical miles  (NM) per hour of travel (TAS ± winds) value, results in a  specific range value. The typical label for specific range is  NM per pound of fuel, or often NM per 1,000 pounds of fuel.  Preflight planning should be supported by proper monitoring  of past fuel consumption as well as use of specified fuel  management and mixture adjustment procedures in flight.  To ensure that sufficient fuel is available for your intended  flight, you must be able to accurately compute aircraft fuel  consumption during preflight planning. Typically, fuel  consumption in gasoline-fueled aircraft is measured in  gallons per hour. Since turbine engines consume much more  fuel than reciprocating engines, turbine-powered aircraft  require much more fuel, and thus much larger fuel tanks.  When determining these large fuel quantities, using a volume  measurement such as gallons presents a problem because  the volume of fuel varies greatly in relation to temperature.  In contrast, density (weight) is less affected by temperature  and therefore, provides a more uniform and repeatable  measurement. For this reason, jet fuel is generally quantified  by its density and volume.  knots). Pilots, therefore, should learn to convert wind speeds  that are reported in knots to mph.  A knot is 1 nautical mile per hour (NMPH). Because there are  6,076.1 feet in 1 NM and 5,280 feet in 1 SM, the conversion  factor is 1.15. To convert knots to mph, multiply speed in  knots by 1.15. For example: a wind speed of 20 knots is  equivalent to 23 mph.  Most flight computers or electronic calculators have a  means of making this conversion. Another quick method of  conversion is to use the scales of NM and SM at the bottom  of aeronautical charts.  Fuel Consumption  Converting Knots to Miles Per Hour  GS GS = D/T  Distance D = GS X T  Time T = D/GS  Basic Calculations  Converting Minutes to Equivalent Hours  16-11  Heading Wind Track  Wind  correction  angle  Desired course  090°  075° 