The satellites were accurately injected into their transfer orbits about 28 minutes and 33 minutes after liftoff, respectively.
Eutelsat-21B will be positioned above the equator at 21.5°E. It will deliver telecommunications services, data services for corporate networks and governmental administrations, and IP access in Europe, North and West Africa, the Middle East and Central Asia.
Star One-C3, to be positioned at 75°W or 84°W, will provide direct TV broadcast, telephone and long-distance domestic communications services for Brazil and South America.
The payload mass for this launch was 9216 kg; the satellites totalled 8250 kg, with payload adapters and dispensers making up the additional 966 kg.
The solid boosters were jettisoned 2 min 22 sec after main engine ignition, and the fairing protecting the payload during the climb through Earth's atmosphere was discarded at 3 min 28 sec.
The launcher's main engine shut down at 8 min 51 sec; six seconds later, the main cryogenic stage separated from the upper stage and its payload.
Four seconds after main stage separation, the engine of the cryogenic upper stage ignited to continue the journey. The engine shut down at 24 min 58 sec into the flight, at which point the vehicle was travelling at 9352 m/s (33 667 km/hr) at an altitude of 654.6 km. The conditions for geostationary transfer orbit injection had been achieved.
At 28 min 03 sec after main engine ignition, Eutelsat-21B separated from the upper stage, followed by Star One-C3 at 33 min 17 sec. Ariane 5's flight operations were completed 48 min 47 sec after main engine ignition.