108 

14 CFR Ch. I (1–1–19 Edition) 

Pt. 60, App. A 

5. G

ROUND

E

FFECT

 

a. For an FFS to be used for take-off and 

landing (not applicable to Level A simula-
tors in that the landing maneuver may not 
be credited in a Level A simulator) it should 
reproduce the aerodynamic changes that 
occur in ground effect. The parameters cho-
sen for FFS validation should indicate these 
changes. 

(1) A dedicated test should be provided that 

will validate the aerodynamic ground effect 
characteristics. 

(2) The organization performing the flight 

tests may select appropriate test methods 
and procedures to validate ground effect. 
However, the flight tests should be per-
formed with enough duration near the 
ground to sufficiently validate the ground- 
effect model. 

b. The NSPM will consider the merits of 

testing methods based on reliability and con-
sistency. Acceptable methods of validating 
ground effect are described below. If other 
methods are proposed, rationale should be 
provided to conclude that the tests per-
formed validate the ground-effect model. A 
sponsor using the methods described below 

to comply with the QPS requirements should 
perform the tests as follows: 

(1) Level fly-bys. The level fly-bys should 

be conducted at a minimum of three alti-
tudes within the ground effect, including one 
at no more than 10% of the wingspan above 
the ground, one each at approximately 30% 
and 50% of the wingspan where height refers 
to main gear tire above the ground. In addi-
tion, one level-flight trim condition should 
be conducted out of ground effect (e.g., at 
150% of wingspan). 

(2) Shallow approach landing. The shallow 

approach landing should be performed at a 
glide slope of approximately one degree with 
negligible pilot activity until flare. 

c. The lateral-directional characteristics 

are also altered by ground effect. For exam-
ple, because of changes in lift, roll damping 
is affected. The change in roll damping will 
affect other dynamic modes usually evalu-
ated for FFS validation. In fact, Dutch roll 
dynamics, spiral stability, and roll-rate for a 
given lateral control input are altered by 
ground effect. Steady heading sideslips will 
also be affected. These effects should be ac-
counted for in the FFS modeling. Several 
tests such as crosswind landing, one engine 

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