Editing Airspeed indicator (section)

== Colour-coded speeds and ranges ==
The ASI has standard colour-coded markings to indicate safe operation within the limitations of the aircraft.  At a glance, the pilot can determine a recommended speed (V speeds) or if speed adjustments are needed.  Single and multi-engine aircraft have common markings.  For instance, the green arc indicates the normal operating range of the aircraft, from ''V''<sub>S1</sub> to ''V''<sub>NO</sub>.  The white arc indicates the [[flap (aeronautics)|flap]] operating range, ''V''<sub>SO</sub> to ''V''<sub>FE</sub>, used for approaches and landings.  The yellow arc cautions that flight should be conducted in this range only in smooth air, while the red line (''V''<sub>NE</sub>) at the top of the yellow arc indicates damage or structural failure may result at higher speeds.<ref name=ASI />{{rp|8–9}}

The ASI in multi-engine aircraft includes two additional radial markings, one red and one blue, associated with potential engine failure.  The radial red line near the bottom of green arc indicates ''V''<sub>mc</sub>, the minimum indicated airspeed at which the aircraft can be controlled with the [[critical engine]] inoperative.  The radial blue line indicates ''V''<sub>YSE</sub>, the speed for best rate of climb with the [[critical engine]] inoperative.<ref name=FAA2>{{cite book |title=Airplane Flying Handbook, FAA-H-8083-3B |date=2016 |publisher=U.S. Dept. of Transportation, FAA |at=12-2 |url=https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/airplane_handbook/media/14_afh_ch12.pdf |access-date=10 October 2018}}</ref>