No it doesn't break the sound barrier...
QUOTE
Not since the Aerospatiale-BAC Concorde — capable of cruising at twice the speed of sound — has any commercial airliner been able to sustain supersonic performance, and according to retired Boeing 777 and Airbus captain and current airline flight instructor Lim Khoy Hing, it's not possible.
In a blog post from 2011, one curious flyer asked whether supersonic speeds had been reached on a flight to London onboard a 777.
Captain Lim explained:
"Even if there is a strong tail wind pushing the plane forward and the ground speed may have exceeded the theoretical speed of sound, in reality, the plane has not gone supersonic.
"The confusion arises between the understanding of ground speed and the plane's speed. The ground speed is the speed at which an object travels relative to a fixed point on the Earth's surface. The difference between ground speed and airspeed is caused by the influence of winds on the overall speed of the aircraft.
"This is analogous to you walking at 2 kmh along a [moving sidewalk] that is moving at 2 kmh. Your actual movement towards your plane at the gate is pretty fast at 4 kmh (2 + 2) but as far as you are concerned, you are still walking at 2 kmh!"
So there you go. Even if your flight is fortunate enough to have a helpful push from the jet stream, it's not about to go near supersonic speeds in level flight.[/quote]

Posted:
Wed Jan 14, 2015 1:45 pm
by Ian Warren

British Airways looking for more patronage, we did have the Concorde, today 777 SUPER

, when you compare actual speed as well ALT also determines ground speed ... wonder who writes these in travel mags.

Posted:
Wed Jan 14, 2015 2:11 pm
by Charl
Eggzackly... next time I'm in a hurry across the Atlantic, definitely will go BA 777, no other...
