dissipating requirements of the brakes. 
There will be a maximum design landing 
weight specified for each airpIane and this 
limitation must be respected because of 
critical landing loads, arresting loads, or 
brake requirements. Of course, any air- 
plane will have a limiting touchdown rate 
of descent specified with the maximum land- 
ing weight and the principal landing load 
limitations will be defined by the combina- 
tion. of gross weight and rate of descent at 
touchdown. 
(2) The surface winds must be considered 
because of the large effect of a headwind or 
tailwind OR the landing distance. In the 
case of the crosswind, the component of 
wind along the runway will be the effective 
headwind or tailwind velocity. Also, the 
crosswind component across the runway will 
define certain requirements of lateral control 
power. The airplane which exhibirs large 
dihedral effect at high lift coefficients is 
quite sensitive to crosswind and a limiting 
crosswind component will be defined for the 
configuration. 
(3) Press.w~ dtitsde and tmpma~e will 
affect the landing distance because of the 
effect on the true airspeed for landing. 
Thus, pressure altitude and temperature must 
be considered to define the density altitude. 
(4) The runway condition must be con- 
sidered for its effect on landing distances. 
Runway slope of ordinary values will ordi- 
narily favor selection of a runway for a 
favorable headwind at landing. The surface 
condition of the runway will determine 
braking effectiveness and ice or water on the 
runway may produce a considerable increase 
in the minimum landing distance. 
Thus, preparation for the landing must in- 
clude determination of the landing distance of 
the airplane and comparison with the runway 
length available. Use of the angle of attack 
indicator and the mirror landing system will 
assist the pilot in effecting touchdown at the 
desired location with the proper airspeed. Of 
NAVWEPS OD-BOT-BO 
APPLICATION OF AERODYNAMICS 
TO SPECIFIC PROBLEMS OF FLYING 
course, the landing is not completed until the 
airplane is slowed to turn off the runway. 
Control of the airpIane must be maintained 
after the touchdown and proper technique must 
be used to decelerate the airplane. 
TYPICAL ERRORS. There are many un- 
desirable consequences when basic principles 
and specific procedures are not followed during 
the approach and landing. Some of the typical 
errors involved in landing accidents are out- 
lined in the following discussion. 
The steep, low power approach leads to an 
exce.rsive rate of descent and the possibility of a 
hard landing. This is particularly the case 
for the modern, low aspect ratio, swept wing 
airplane configuration which incurs very large 
induced drag at low speeds and does not have 
very conventional flare characteristics. For 
this type of airplane in a steep, low power 
approach, an increased angle of attack without 
a change of power setting may not cause a 
reduction of rate of descent and may even in- 
crease the rate of descent at touchdown. For 
this reason, a moderate stabilized approach is 
necessary and the principal changes in rate of 
descent must be controlled by changes in power 
setting and principal changes in airspeed must 
be controlled by changes in angle of attack. 
‘An excessive angle of attack during the ap- 
proach and landing implies that the airplane is 
being operated at too low an airspeed. Of 
course, excessive angle of attack may cause the 
airplane to stall or spin and the low altitude 
may preclude recovery. Also, the low aspect 
ratio configuration at an excessively low air- 
speed will incur very high induced drag and 
will necessitate a high power setting or other- 
wise incur an excessive rate of descent. An 
additional problem is created by an excessive 
angle of attack for the airplane which exhibits 
a large dihedral effect at high lift coefficients. 
In this case, the airplane would be more sensi-