Summary of the 60-to-1 Rule and Other Rules & Formulas - Cont'd

JOINT ADVANCED MULTI-ENGINE T-44A

First, compute our VDP: HAT/300 = 637/300 = 2.1 NM from end of runway

The distance from the FAF to the runway is 4.8 NM; FAF to computed VDP is 4.8 - 2.1 =

2.7 NM

Use the timing formula:

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 60-to-1 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

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 SRT = (TAS/20) + 7

Arcing Lead Points. Now that we know how to determine turn radius, you can use the following 60-

to-1 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.

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RADIO INSTRUMENTS STAGE