RULES OF THUMB

RULES OF THUMB 

DESCENT PLANNING FOR 3 DEGREE GLIDE SLOPE

Rate of descent  = Airspeed x 5         Example :: 100 Kts x 5 = 500 ft/min

Distance for descent is height change x 3   Example: descend from 7,000ft to 1,000ft (6,000ft) 6 x 3 = 18nm. Start descent 18nm

TAKE OFF  DISTANCE INCREASE

10% each 1,000ft altitude and 10 degrees above ISA or 10% up slope or dry grass

20% if weight up 10%

30% wet grass

LANDING DISTANCE INCREASE

5% each 1,000ft altitude or 10 degrees above ISA

10% if weight up 10% or 10% down slope or dry grass

30% wet grass

DENSITY ALTITUDE   1 Cº over ISA = 120FT (plus height over ground)

Example:  Eastern 180FT.  OAT 35º = 2,400FT + height 180FT = 2,580FT Density Altitude

TRUE AIRSPEED is indicated airspeed + 2% each 1,000FT

Example 100 Kts indicated at 5,000FT is 100 + 2% x 5 = 110 Kts TAS. (Caution over Vne)

ALTIMETER ERROR   4FT x  temp deviation from ISA X height (1000)

Example  OAT is 20 deg at 5,000FT. But ISA is 5 (difference 15 deg)  4 x 15 x 5 = 300FT.

Altimeter under-reads 300FT. True altitude 5,300FT. Caution- below ISA, altimeter over-reads

WIND COMPONENTS

NAVIGATION  - OFF TRACK            1 in 60 rule :  1 degree off track is 1nm in 60

Distance off track / (divided by) distance gone x 60 = track error in degrees

Distance off track / (divided by) distance to go x 60 = closing angle. (Add together)

BEST SPEED (Lift/Drag) for max Range / Rate of Climb / Glide is stall speed clean  x 1.4

Example: stall speed 50 Kts x 1.4 = 70 Kts. Best speed if low on fuel or gliding engine out.

COORDINATES  eg 12.45.30 N  Degrees / minutes / seconds

1  Degree  =  60 nm or 110 Km      Example    13.45.30 is 60 miles north

1 Minute   =   1 nm about 2 Km     Example   12.46.30 is 1 mile north

1 Second  = 30 metres                 Example    12.45.40 is 300m north