WASHINGTON — Arianespace on April 5 launched two satellites for telecom operators that for separate reasons were both more than a year behind their original launch schedules.

An Ariane 5 rocket took off at 5:34 p.m. Eastern from the European spaceport in French Guiana, delivering Japanese operator Sky Perfect Jsat’s DSN-1/Superbird-8 satellite into a geostationary transfer orbit 28 minutes after liftoff. British fleet operator Avanti’s Hylas-4 satellite separated another six minutes later.

The launch is the 98th launch of an Ariane 5 rocket, and the first since the implementation of more rigorous mission data checking after incorrect inclination data caused a January mission to place two satellites in the wrong orbits.

DSN-1/Superbird-8 was originally scheduled to launch in 2016, but was damaged during transport to the Guiana Space Center, requiring repairs. Japanese satellite manufacturer Mitsubishi Electric built the satellite on its DS2000 platform, with NEC Corp. managing manufacturing.

Sky Perfect Jsat’s Superbird-8 replaces the 18-year-old Superbird-B2 satellite at 162 degrees east. The satellite carries Ku- and Ka-band capacity for the operator’s commercial communications services in Japan, and the X-band DSN-1 payload for Japan’s Ministry of Defense.

Hylas-4 was initially planned for a launch in early 2017, but ran into manufacturing delays concurrent with deepening financial troubles for Avanti. The operator in 2016 opted to forgo a company sale in favor of a refinancing deal to preserve Hylas-4, a satellite with three times more capacity than the rest of Avanti’s fleet.

Built by Orbital ATK on its GEOStar-3 platform, Hylas-4 carries 64 Ka-band spot beams covering Europe and Africa, and four steerable Ka-band beams that can reach out to South America and over to the Middle East.

Avanti expects Hylas-4 will give the company a competitive edge since its two operational satellites, Hylas-1 and Hylas-2, are both struggling to compete against newer high-throughput satellites. In the next few years, several operators have plans to add large amounts of high-throughput capacity over Europe, the Middle East and Africa — Avanti’s core markets. Eutelsat, Spacecom, Global IP, and others will all make for an even more competitive market as operators strive to capture lucrative broadband business.

Both Avanti and Sky Perfect Jsat had to wait so long for this launch that they inverted the launch order for other missions both had underway. Japan’s DSN-2 satellite, intended to be the second of three X-band defense satellites, launched first in January 2017 on an H2A rocket from Mitsubishi Heavy Industries. Avanti is still awaiting the launch of Hylas-3, a mission first expected in 2015, but now is planned for this year, though it could slip further. The European Space Agency’s European Data Relay Satellite-C satellite from OHB Systems of Bremen, Germany is carrying Hylas-3 as a hosted payload.