Star_world From Ireland, joined Jun 2001, 1234 posts, RR: 0 Reply 1, posted (5 years 10 months 3 weeks 3 days 20 hours ago) and read 1152 times:
The pitot tube is placed out of the rotor effect area, so the reading will be accurate. The ASI works just like a fixed wing aircraft ASI would - it only shows forward speed. The sideways / backwards movement is generally performed at a much lower speed, so having an airspeed for these directions isn't essential. Plus there's always a GPS groundspeed indicator, if fitted.