Having piloted the 777, IMO, it’s a great aircraft.
As far as tracking. It is my understanding that most new aircraft (commercial and private) will have ADS-B Out — the Automatic Dependent Surveillance Broadcast Out system installed, and that older aircraft can and will be retrofitted.
Each aircraft will transmit it’s position automatically without the use of radar. This will enable more efficient tracking up to the point of the last known location.
