Cessna 172 R - CRUISE

Supplement POH Cessna 172 R&S
Page 5-3
Issue 3
Revision -, June 2016
CRUISE
The cruising altitude should be selected based on a
consideration of trip length, winds aloft and the airplanes
performance. A typical cruising altitude and the expected wind
enroute have been given for this sample problem. However, the
power setting selection for cruise must be determined based on
several considerations. These include the cruise performance
characteristics presented in Figures 5-4a. Considerable fuel
savings and longer range result when lower power settings are
used.
Figure 5-4a shows a range of 802 NM at zero wind, a power
setting of 70% and altitude of 6,000 ft.
With an expected headwind of 10 Knot at 5,500 ft altitude the
range has to be corrected as follows:
Range at zero wind (standard tanks)............................ 802 NM
Reduction due to Headwind........... (7.6 h x 10 Knots) = 76 NM
Corrected Range........................................................... 726 NM
This shows that the flight can be performed at a power setting
of approximately 70% with full tanks without an intermediate fuel
stop.
Figure 5-4a is based on ISA conditions. For a temperature of
16°C above ISA temperature, according to Note 3, true airspeed
and maximum range are increased by 1.6 %.
The following values most nearly correspond to the planned
altitude and expected temperature conditions. Engine Power
setting chosen is 70%.
The resultants are:
Engine Power:.....................................................................70%
True Airspeed: ................................................................. 101 kt
Fuel Consumption in cruise: ...................18.6 l/h (4.9 US gal/h)