
 JOINT ADVANCED MULTIENGINE T44A
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First, compute our VDP: HAT/300 = 637/300 = 2.1 NM from end of runway
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The distance from the FAF to the runway is 4.8 NM; FAF to computed VDP is 4.8  2.1 =
2.7 NM
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Use the timing formula:
a)
144 seconds (from timing box) / 4.8 (NM from FAF to MAP) = 30 seconds per mile
b) 30 (seconds per mile) X 2.7 NM = 81 seconds = 1 minute 21 seconds
Or, using another, easier formula:
Timing to MAP (from timing box) 10% of HAT = Time (in seconds) to VDP
Same example: 144 seconds (from timing box)  10% of 637 = 144  63 = 81 seconds = 1
minute 21 seconds
Determining Turn Radius/Lead Points. Turn radius is not really a 60to1 relationship. However, it is
important to determine your turn radius at various altitudes and airspeeds. An aircraft's turn radius is
dependent on TAS and AOB. The higher the TAS, the larger the turn radius. As bank angle is
increased, the turn radius decreases. In order to develop a technique for determining your turn radius,
you must keep one of the variables (TAS or bank) constant. Since most procedures are based on a 30°
bank, the following two relationships will provide the distance required to turn an aircraft 90° using
30° of bank. The first relationship is easier to use, but is not as accurate.
TR = NM/MIN 2
or
TR = (NM/MIN)2 / 10
Example: 150 KIAS~160 KTAS~2.67 NM/MIN
2.67 2 = .67 NM (using first formula)
(2.67) 2 / 10 = .71 NM (using second formula)
The following formula will provide you the TR for a standard rate turn (SRT):
SRT = 0.5% of TAS (or GS)
Example: 0.5% of 160 KTAS = 0.8 NM turn radius
While we are discussing standard rate turns, here are a couple of relationships that will give you the
bank angle to approximate the SRT:
Bank Angle for SRT = (TAS/10) + 7
Example: 160 KTAS; (160/10) + 7 = 23
of bank
Bank Angle for ½ SRT = (TAS/20) + 7
Arcing Lead Points. Now that we know how to determine turn radius, you can use the following 60
to1 formulas to compute arcing lead radials:
Radials per NM = 60 / Arc (DME)
Example: On a 10 DME arc, there are 6 radials per nautical mile.
Lead radials = TR X Radials/NM
Example: If our turn radius is 0.8 NM, and we are on a 10 DME arc, our lead point will be
4.8 (~5) radials prior to the desired radial.
470
RADIO INSTRUMENTS STAGE

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