Notes:The highest noted groundspeed in level flight was 156kt, unfortunately I did not take photo at the time.
In level flight at FL95 the highest documented groundspeed was 150kt (112 KTAS which is maximum cruise speed for the type).
During descend at 110 KIAS (nearly Vno) at FL85 (125 KTAS) groundspeed was 168kt).
That day at FL100 prevailing winds was about 50 kt from west. It was on the route between EPPO and EPBC. Some details you can read from PFD and/or MFD.
Name:Brian O 'Keeffe
Airline:Waterford Aero Club
Date:28 May 2009
Notes:SW of Ferbane, Ireland. FL050, tailwind component of 40kts :)