AIRPLANE
OPERATIONS
MANUAL
FLIGHT PLANNING
EMB-145 A1 and A1P LB
REVISION 40
1-05-05
Page
11
Code
02
AOM-145/1114
CRUISE - WIND ALTITUDE TRADE
The following tables allow the determination of the break-even wind in
order to maintain the same ground specific range at another altitude
than the one planned initially. Long Range Cruise or Maximum Speed
Cruise tables are provided.
These tables are based on the comparison between ground specific
range at the new and actual altitudes. They do not consider
climb/descent time, fuel and distances. The tables may be used in-
flight, where the wind information is available and more accurate.
Evaluation Method
1. Check the wind factors for actual and new altitudes.
2. Calculate the difference between new and actual wind factors.
This number may be negative or positive.
3. The BREAK-EVEN WIND at the new altitude is the wind
component at actual altitude plus the difference calculated on
step (2).
Example:
40000 lb of actual cruise weight, LRC:
Actual Flight Level: FL 280, -10 kt (headwind)
New Flight Level: FL 350, -20 kt (headwind)
1. Wind factor FL 280 = 52, Wind factor FL 350 = 12
2. Difference = 12 (new FL) - 52 (actual FL) = -40
3. Break Even Wind = -10 (Wind actual FL) + (-40) (difference) =
-50 kt Wind on FL 350.
(20 kt headwind) is more favorable than Break-Even Wind
(50 kt headwind). Therefore, climb to FL 350.
To Next Page
