Commercial Low Supersonic (Non-SST)

[BHXUK1]

When on flight tracking sites, in particular flightaware, sometimes it will display a flight flying between mach .90-1

1) Is this accurate?
2) Are high subsonic (.90Mach) or supersonic speeds capable on subsonic aircraft, especially heavies?

[pilotgolfer]

It's quite possibly because of the jet stream giving them an extra boost of speed in flight. That's what my guess would be.

[thxcollins]

You're seeing groundspeed on Flightaware. Like pilotgolfer mentioned, with a tailwind it's possible to see even 1200kt speeds at times.

[aaronacw]

Yes, its probably accurate as it is measuring the groundspeed of the aircraft, not the airspeed, and the jetstreams and gusts at altitude can mean the airspeed varies up to 150 or so km/h(afaik from watching the flight info program on too many flights.

And yes, high subsonic speeds are possible on subsonic aircraft, with business jets being the most common aircraft in this speed range. An example is the Cessna Citation X, with a cruise speed of Mach 0.92. Im not 100% sure what the VNE for heavies is, but I think it would be above Mach 0.9. Dont quote me on any of this though, but im not a expert on this, so if I am wrong please correct me.

Hope this helps
Aaron

[AJ]

I've been Mach 0.91 in a 747-400 (Mmo 0.92) which was awfully loud. The 767 has an Mmo or 0.86.

[Gabriel]

Now, giving a groundsped in Mach is as ridiculous and meaningless as it gets.

[TUNISAIR745]

Now, giving a groundsped in Mach is as ridiculous and meaningless as it gets.

Exactly, it's the first time i hear about a ground speed in mach!!
Can someone explain to me how this can be possible??

[BHXUK1]

thanks for that