Aero Chapter 03, High AOA/Stall/Spin
T-45 Aerodynamics Student Workbook
The AOA system calculates the optimum AOA for approach considering the gross weight and
configuration of the aircraft. At the optimum approach AOA, the IAS will be greater for a greater gross
weight. The aircraft gross weight calculation begins with the zero fuel weight, which is approximately
10,400 pounds and includes trapped fuel, oil, and two aircrew. (See NATOPS chapter 1 and the Pocket
Checklist.) To ensure the AOA is indicating properly during deceleration, the pilot should compare the
indicated AOA to the IAS computed from the gross weight. Using the NATOPS pocket checklist, at 17
units AOA, the T-45 airspeed should be 116 +/- 2 KIAS at 11,400 lb gross weight (1,000# of fuel
remaining). Add or subtract 2.5 kts for every 500# above or below a gross weight of 11, 400#. Add 5
KIAS for every 1,000# of additional gross weight above 11,400# or subtract 5 kts if the gross weight is
1,000# less than 11,400#.
The AOA probe rotates to balance the pressure in its slots (Figure 63). The probe senses the relative
wind and sends the probe angle to both cockpit AOA indicators and the airborne data recorder for the ADI
display and head-up display (HUD). The AOA indicator, ADI, and HUD display the AOA to the pilot in
units from 0 to 30.
Figure 63: AOA COMPONENTS (T-45C)
The AOA indicator (Figure 63) provides optimum approach and other airspeed information. On all Navy
aircraft, the optimum approach speed is with the needle at precisely three oclock on the AOA indicator.
Indicators or bugs on the face of the AOA indicator highlight the maximum endurance (14 units) and
maximum range (12-13 units depending on gross weight). Max range airspeed decreases with
decreasing gross weight. The off flag indicates the AOA indicator is out of service.