TM 55-1510-222-10
b.
Fahrenheit to Celsius Temperature Conversion.
Convert reported field temperatures at the departure
and destination airports from Fahrenheit to Celsius using
the Fahrenheit to Celsius Temperature Conversion
graph. Enter the chart at the appropriate value on the
°F scale, read up to the reference line and left to the
corresponding value in °C.
Billings-Logan International 59°F.............................15°C
Natrona County International 68°F ..........................20°C
c.
Pressure
Altitude.
To
determine
the
approximate pressure altitude at origin and destination
airports, add 1000 feet to field elevation for each 1.00
in. Hg that the reported altimeter setting value is below
29.92 in. Hg, and subtract 1000 feet for each 1.00 in. Hg
above 29.92 in. Hg. Always subtract the reported
altimeter setting FROM 29.92 in. Hg. Then multiply the
answer by 1000 to find the difference in feet between
field elevation and pressure altitude.
Pressure Altitude at BIL:
29.92
-30.07
-0.15
-0.15 x 1000 feet = -150 feet
Field Elevation ................................................. 3649 feet
Pressure Altitude Correction............................ - 150 feet
Field Pressure Altitude.....................................3499 feet
Pressure Altitude at CPR:
29.92
-29.27
-0.65
0.65 x 1000 feet = 650 feet
Field Elevation ................................................. 5348 feet
Pressure Altitude Correction ...........................+ 650 feet
Field Pressure Altitude.....................................5998 feet
d.
Wind Components. Determine the headwind
(tailwind) and crosswind component for the selected
runway. Compute the angle between the reported wind
at Billings-Logan International of 290° and the selected
runway heading of 340° to be 50 degrees. Locate the
line of for 50°
angle between wind direction and flight
path on the graph. Trace along the 50° line to locate the
point midway between. the 10 and 20 wind speed lines.
Read left to obtain the headwind component and down
to obtain the crosswind component.
Headwind Component....................................... 10 knots
Crosswind Component...................................... 12 knots
e.
Takeoff Weight. The following examples
illustrate the use of graphs which may restrict takeoff
weight.
NOTE
Do not exceed the Maximum Takeoff
Weight Limitation of 16,000 pounds.
(1) Maximum
Takeoff
Weight
To
Achieve
Positive One-Engine-Inoperative Climb at Lift-Off. Enter
the graphs at 3499 feet pressure altitude, 15°C, and
read:
Flaps Up ........................................................ 16,000 lbs
Flaps Approach.............................................. 16,000 lbs
(2) Maximum Enroute Weight For 50-Ft/Minute
One-Engine-Inoperative Climb. To determine the
maximum takeoff weight, the weight of the fuel used to
reach the MEA is added to the maximum enroute weight
obtained from the SERVICE CEILING - ONE ENGINE
INOPERATIVE graph. Use the TIME, FUEL, AND
DISTANCE TO CRUISE CLIMB graph to determine the
weight of the fuel used to climb. Use the Cruise Power
tables to determine the weight of the fuel used to cruise
to each MEA. Enter the SERVICE CEILING - ONE
ENGINE INOPERATIVE graph at the conditions for
each enroute MEA. For example, enter the graph at the
highest MEA altitude of 9000 feet, and trace right; enter
again at the MEA FAT of -4C, and trace up. Read the
maximum enroute weight at the MEA at the intersection
of the tracings.
Maximum Enroute Weight For 50-Ft/min One-Engine-
Inoperative Climb:
8000 ft, 0°C ............................... Exceeds Structural
Limit of 16,000 lbs
9000 ft, -4°C . ............................. Exceeds Structural
Limit of 16,000 lbs
7600 ft, 0°C ............................... Exceeds Structural
Limit of 16,000 lbs
Since these weights are all greater than the Maximum
Takeoff Weight Limitation of 16,000 lbs, there is no
additional
limitation
to
meet
enroute
weight
requirements. Anytime the value is less than 16,000
7-4
