PARIS — Satellite fleet operator Intelsat reported May 8 a modest increase in revenue and operating profit for the three months ending March 31 and said it has presold about one-third of the commercial capacity on board the IS-22 satellite that was launched in March and will enter service by June.

IS-22, which will operate at 72 degrees east longitude, includes a UHF payload fully sold to the Australian Defence Force (ADF) for about $317 million over the satellite’s 15-year service life.

ADF made hefty prelaunch payments as part of the contract, and Intelsat expects that future ADF payments will average $20 million per year.

In a conference call with investors, Intelsat Chief Executive David McGlade said the company has sold about one-third of the C- and Ku-band capacity on IS-22 and that it should take 12 to 18 months to ramp up sales to reach 70 percent of capacity.

Luxembourg- and Washington-based Intelsat, which is the world’s largest commercial satellite fleet operator, reported that its entire fleet of satellites was 79 percent full as of March 31. This percentage reflects only the 2,075 transponders aboard satellites that are fully stabilized in orbit.

Intelsat also generates revenue, albeit in modest amounts, from transponders on satellites nearing retirement that, to save fuel, are no longer stabilized on their north-south axis.

Intelsat reported revenue of $644.2 million for the three months ending March 31, up 1 percent from a year ago. Operating income, at $352.7 million, was also up by 1 percent. Intelsat said its adjusted EBITDA, or earnings before interest, taxes, depreciation and amortization, was 77 percent of revenue, compared with 78 percent a year ago.

Backlog, at $10.5 billion at March 31, was down from $10.7 billion three months earlier.

Intelsat’s owners, which are mainly private-equity investment companies, have allowed the company to embark on a 10-satellite capital investment program, with launches between March 2012 and the end of 2015, despite Intelsat’s $16 billion in debt.

IS-22 was the first of these 10. Of the nine remaining, four are set for launch in 2012, a year that should represent a peak in the company’s capital spending of between $775 million and $850 million. Spending will fall to no more than $625 million in 2013 and $600 million in 2014, assuming the launch schedule does not change, Intelsat said.

Much of the new satellite capacity will replace existing satellites, but there is enough expansion potential in the coming fleet additions to provide a boost to revenue starting late this year, Intelsat Chief Financial Officer Michael McDonnell said during the conference call.

The ADF contract is the earliest contributor to the revenue boost. Intelsat is hoping to sell to the U.S. Department of Defense — which will be using the ADF-owned capacity on IS-22 — a similar UHF payload on the IS-27 satellite scheduled for launch in early 2013.

The company has said that budget cuts at the U.S. Department of Defense have complicated Intelsat’s IS-27 sales effort.

Defense officials, Intelsat has said, are focusing on their own satellites instead of on hosted payload options of the kind Intelsat is offering on IS-27 despite the fact that government payloads on commercial satellites may offer lower costs of delivered bandwidth and a more predictable development schedule.

Intelsat also is counting on aeronautical and maritime revenue once it puts into orbit 10 dedicated beams over the oceanic shipping and air-traffic routes on seven satellites.

Intelsat, as expected, continues to see reduced revenue from what it calls its “channel” service — point-to-point links — as customers transfer to less-expensive cable connections. This has already occurred in many parts of the world and is now happening in Africa.

Intelsat’s media business continues to grow. The company’s revenue from transponder leases was up 3 percent in the three months ending March 31, mainly because of new business in Latin America and the Caribbean.

Intelsat also does a regular business in selling, often to government customers, satellite bandwidth packages that include capacity on other companies’ satellites. Intelsat said revenue from fixed and mobile satellite services on non-Intelsat satellites was up 8 percent year on year, to $64.4 million, despite a decline in the mobile satellite services portion.

Peter B. de Selding was the Paris bureau chief for SpaceNews.