While a bike can outrun a plane (don't ask me how I found that out ) or a chopper, it can't really outrun the aircraft's line of sight, unless we're dealing with tunnels.
What is 140knots true air speed? Was told it was Cesna 206 turbo at 178knots. But I don't know the difference in that jargon.Radar Identified wrote:On a side note, think the OPP's Cessna 206H has a cruising speed of about 140 knots true airspeed (about 260 km/h). Someone trying to run would really have to floor it for a long period of time!
If it's a 206 Turbo, 178 knots is definitely possible... could be true airspeed or indicated... That's well over 300 km/h. Basically "true" airspeed is the actual speed that the airplane is moving through the air. Squishy - yes, you are correct.
However, aircraft instruments aren't perfect, so let's say the 206 can do 178 knots "true" airspeed. (The aviation abbreviation would be 178 KTAS.) That won't be exactly what shows up on the aircraft's Airspeed Indicator, even on aircraft like an Airbus 380, Boeing 777 or Dash-8 Q400.
Basically the airspeed indicator on aircraft like the 206 works by taking the forward pressure of the air that the plane is flying through (Pitot pressure), and compares it to the air around it (static pressure). Then it measures the difference between the two is because, of course, as you get higher, the air gets thinner - so Pitot pressure alone would be wildly inaccurate if it wasn't compared to static pressure. The airspeed indicator then gives you Indicated Airspeed, but the problem is, the Pitot tube's position affects the reading somewhat - this is true for every airplane. After correcting for that error, we get Calibrated Airspeed. The airspeed indicator was also set based on "standard atmospheric" conditions - temperature of 15C at sea level, 101.32 kPa pressure at sea level, temperature decrease of 1.98C per 1000 feet of altitude gain, etc. So after Calibrated Airspeed, we have to correct for variation from standard atmospheric conditions - and that's where we get our actual speed through the air, or True Airspeed. Confusing enough?
In almost all cases, true airspeed is higher than indicated airspeed. I'd guess that if the 206 Turbo was doing about 160 knots Indicated, it would be about 178 knots True.
Modern airliners still display Indicated Airspeed on their Primary Flight Displays, but they also use the Air Data Computers to calculate True Airspeed. Jet aircraft also have Machmeters, which is a lot more relevant when flying at high speeds and high altitudes.