Knots/Mach Comparison

[sho69607 29]

I just was following this flight on FlightAware (BAW288) and it was showing 578kts @ 37000Ft isnt that something like M. 92 or higher? how could a 747 be cruising that fast. That is well over vMO for even an aircraft as fast as the 747. Was FlightAware displaying inaccurate data or am I converting this incorrectly?

[Angels40 17]

That figure looks like your ground speed, not airspeed. And to get 578 kts would mean that you have a huge tailwind. Chris David

[vololiberista 205]

To get Mach .92 at that airspeed you altitude would be 3,300ft only!!!!vololiberista

[sho69607 29]

so tailwind wont cause an overspeed. I must "knot" be understanding how GS works

[Guest jahman]

so tailwind wont cause an overspeed. I must "knot" be understanding how GS works

Overspeed is with respect to airspeed, not ground speed. According to Adacalc, 538 KN at FL380 is .938M for the Standard Atmosphere (ISA). Since the 744's Mmo is .92M or 527 KN (FL380, ISA), a mere tailwind component of 538 - 527 = 11 KN would do the trick! Cheers, - jahman.