Flight Training Instruction - Cnatra - U.S. Navy

CHAPTER FIVE T-6B PRIMARY INSTRUMENT NAVIGATION
constant, trim is required due to the power change. To maintain 200 KIAS, the “Rule of 100”
provides approximate pitch and power combinations for descents in the T-6: (degrees nose low)
multiplied by (percent torque) = 100. For example, use 10° pitch or 10% torque, 5° pitch and
20% torque.
Common Errors.
1. Loss of heading control due to insufficient rudder, and/or rudder trim.
2. Improper pitch and power setting used for desired airspeed.
503. RATE TURNS
General. Standard rate turns (SRT) and half standard rate turns (½ SRT).
Description. During normal IFR flight along airways, all turns will generally be performed at a
specified rate, either standard or half standard rate. The SRT is 3º per second. At 3º per second,
a turn of 180º will take one minute and a 360º turn will take two minutes. Figure 5-1 shows the
AOB necessary to produce a 3º per second turn at various airspeeds. From the chart, notice that
an aircraft operating at high airspeeds requires a steep AOB to produce a 3º per second turn.
Steep turns are more difficult to fly than shallow turns, since they result in heavy load factors.
For example, a 60º bank turn applies a force of two “Gs” to the aircraft and pilot. To avoid these
“G” forces and provide better control, FAA publications recommend using either a SRT or 30º
AOB turn, whichever occurs first.
Rate turns are practiced initially in level flight, crosschecking the nose with VSI and altimeter,
and the wings on the turn needle. A one needle width deflection produces a ½ SRT and a two
needle deflection produces a full SRT. Performance for SRTs will be 30° heading change every
10 seconds. A ½ SRT will require 20 seconds for every 30° of heading change. Since the AOB
required to produce a constant rate turn will vary with airspeed, the student will need to utilize a
method for determining proper bank for a specific needle deflection. A rule of thumb is to
establish an AOB equal to 10% of the indicated airspeed for a ½ SRT. For example, at 180
KIAS, 18º AOB should initially be established. This value would be doubled for a full SRT (36º
AOB). However, as specified above, use a maximum of 30º AOB while flying instruments.
The above rule is known as the “10 percent rule” and is valid only during balanced flight. If
calibrated correctly, the turn needle always shows the exact rate of turn (even in an unbalanced
condition, but the AOB will vary according to the balance ball’s position).
5-2 BASIC INSTRUMENT PROCEDURES