Applicants seeking an instrument rating or ATP certificate may find these useful.


Calculating Va: (maneuvering speed)

Sqrt of (TOW / MGTOW) * published Va (162mph)

Example:

Actual weight: 24000 lbs. MGTOW: 28,000 lbs
Sqrt of 24000/28000 = 0.926 * 193 (published Va) = 178.68

Calculating lead intercepts for DME arcs and any selected course

TAS / 200

Example:

200KTAS / 200 = 1.0
Therefore, initiate a standard rate turn 1.0nm prior to arriving at the arc.
For a 45 degree intercept to the final approach course, 0.5nm (use FMS/GPS for XTRK information.)
For a 30 degree intercept, initiate at 0.2nm.

Calculating Rate of Descent to track glideslope

(Groundspeed / 60) * 300

Example:

135 knots GS
135/60 = 2.25
2.25 * 300 = 675 FPM

Note: 300 is used because flying a 3-degree glideslope will cause the aircraft to descend 300 feet per nautical mile (FPNM.) If a nonstandard glideslope angle is published on the IAP, use that number instead (i.e. if 3.24 degrees, use 324.)

Alternate method:

Ground speed X 5 = VS to maintain
(Faster to calculate 10 X ground speed / 2 = VS)

Example: 120 KT x 10 = 1200
1200 / 2 = 600 FPM

Alternate method (rule of thumb):

Use 10% of groundspeed, and multiply times 5.

Example:

140 knots GS
140 * 5 = 700FPM

This method is quite accurate, provided a standard 3.00 degree glideslope.

Initiating level-off from climb or descent

10% of Rate of Climb/Descent

Example:

If climbing at 500FPM, initiate level-off 50 feet below target altitude.

Calculating bank angles for standard rate turns

10% of TAS / 1⁄2 of that number

Example:

120KTAS
12 + 6 = 18 degrees angle of bank

Calculating roll-out from steep (45 degree bank angle) turns

Initiate roll-out at a heading equivalent to 1⁄2 the bank angle.

Example:

45 degree bank
Turn initiated at 360 degrees to the left
Initiate rollout at (45 / 2) 22.5 degrees prior to reaching 360, i.e. 023 degrees.

Calculating VDP (or PDP, Planned Descent Point)

Distance-based VDP/PDP:

MDA (HAT) / 300

Example:

MDA is 430 ft. AGL. 430/300 = 1.4nm

Time-based VDP/PDP:

Subtract 10% of the MDA (HAT) from the time between FAF and MAP

Example:

MDA is 430 ft. AGL
Time between FAF and MAP is 3:54
10% of 430 = 43
Subtract 43 seconds from 3:54 = 3:11 to VDP/PDP

How far out to start a descent? (3° glide)

Altitude to lose / 300
Example: 6000’ to lose, start descent 20 NM out.
(6000/300 = 20 NM)

Convert climb gradient from ft/NM to FPM

Ft/nm requirement x NM per minute

Example: DP requires 300 ft/NM climb.
Your ground speed is 120KT, which is 2NM per minute (120 KT / 60 min = 2 NM per minute).
300 x 2 = 600 FPM