Figure 10-30. Crosswind component chart.
Landing Charts
Landing performance is affected by variables similar to those
affecting takeoff performance. It is necessary to compensate
for differences in density altitude, weight of the airplane, and
headwinds. Like takeoff performance charts, landing distance
information is available as normal landing information, as
well as landing distance over a 50 foot obstacle. As usual, read
the associated conditions and notes in order to ascertain the
basis of the chart information. Remember, when calculating
landing distance that the landing weight will not be the same
as the takeoff weight. The weight must be recalculated to
compensate for the fuel that was used during the flight. |
Sample Problem 11
Pressure Altitude...............................................1,250 feet
Temperature......................................................... Standard
Refer to Figure 10-31. This example makes use of a landing
distance table. Notice that the altitude of 1,250 feet is not
on this table. It is, therefore, necessary to interpolate to find
the correct landing distance. The pressure altitude of 1,250
is halfway between sea level and 2,500 feet. First, find the
column for sea level and the column for 2,500 feet. Take the
total distance of 1,075 for sea level and the total distance of
1,135 for 2,500 and add them together. Divide the total by
two to obtain the distance for 1,250 feet. The distance is 1,105
feet total landing distance to clear a 50 foot obstacle. Repeat
this process to obtain the ground roll distance for the pressure
altitude. The ground roll should be 457.5 feet.
Sample Problem 12
OAT.......................................................................... 57 °F
Pressure Altitude.............................................. 4,000 feet
Landing Weight...........................................2,400 pounds
Headwind.............................................................. 6 knots
Obstacle Height..................................................... 50 feet
Using the given conditions and Figure 10-32, determine the
landing distance for the aircraft. This graph is an example of
a combined landing distance graph and allows compensation
for temperature, weight, headwinds, tailwinds, and varying
obstacle height. Begin by finding the correct OAT on the
scale on the left side of the chart. Move up in a straight
line to the correct pressure altitude of 4,000 feet. From this
intersection, move straight across to the first dark reference
line. Follow the lines in the same diagonal fashion until the
correct landing weight is reached. At 2,400 pounds, continue
in a straight line across to the second dark reference line.
Once again, draw a line in a diagonal manner to the correct
wind component and then straight across to the third dark
reference line. From this point, draw a line in two separate
directions: one straight across to figure the ground roll and
one in a diagonal manner to the correct obstacle height. This
should be 975 feet for the total ground roll and 1,300 feet for
the total distance over a 50 foot obstacle. |