UPDATED May 30 at 11:53 p.m. EDT

PARIS — Britain is opposing a U.S. government request to the International Maritime Organization (IMO) that mobile satellite services operator Iridium be evaluated as a provider of global maritime-distress services.

In a submission to the London-based IMO in preparation for a June 30-July 7 meeting to evaluate the Iridium bid, Britain argues that Iridium’s current satellite constellation is not reliable enough to be certified as a maritime emergency communications provider.

While Iridium’s status may change as it takes steps to meet IMO requirements for Global Maritime Distress and Safety Service (GMDSS) providers, notably with the launch of Iridium’s second-generation constellation of satellites, the company’s current shortcomings should disqualify its current GMDSS bid, according to the British IMO submission.

The U.S. government position to the IMO does not specifically rebut the British viewpoint, but says that whatever GMDSS requirements Iridium does not meet now it will meet in the near term. For the moment, the U.S. government says, Iridium should be evaluated by the International Maritime Satellite Organization (IMSO) to determine its services’ characteristics.

The body of the U.S. position paper consists of McLean, Virginia-based Iridium addressing, one by one, the IMO GMDSS requirements, and reminding the IMO that Iridium already has a large installed base of maritime and aeronautical customers.

The British position mirrors statements made by London-based Inmarsat, an Iridium competitor and the only certified GMDSS provider, which has produced Iridium network-reliability figures that differ from what Iridium submitted to the IMO.

Iridium says its current constellation and associated ground network “is capable of fully complying with the criteria and requirements” the IMO has set for GMDSS providers. The company and the U.S. government further say Iridium is willing to subject its network to a detailed technical review by London-based IMSO, as is required by IMO GMDSS guidelines.

To be considered as a GMDSS service provider, Iridium must be able to demonstrate 99.9 percent network reliability, equivalent to less than nine hours of outages in a given year. In its IMO proposal, the company says its network was unavailable for just six hours in all of 2012, and 2.2 hours in 2013.

The British government counters that the Iridium reliability figures have not been validated by IMSO and do not include Earth station reliability in the assessment. 

A key difference between the two sides centers on how the network would recover from an in-orbit failure. Iridium says that depending on where in its orbit the satellite is when it fails, it would take at most six minutes for the system to recover functionality. If the failure occurred away from the equator —  Iridium’s constellation is most thinly spread near the equator — the outage would be of much shorter duration.

Iridium operates a constellation of 66 operational satellites. Since 2001, it has lost 10 satellites to in-orbit failures, including one in an orbital collision with a dead Russian satellite.

In its 2013 financial statement submitted to the U.S. Securities and Exchange Commission, Iridium said its current constellation consists of 11 satellites in each of six different orbital planes, plus a total of four spares. For the British, this suggests that there are no spares in two of the six orbital planes.

In its year-end financial report, Iridium said that if there is no spare in a given orbital plane, a failed satellite would take “at least a year” to be replaced by moving another spacecraft into position. 

That would appear to violate one of the GMDSS criteria of having outages limited to one hour at most.

However, Iridium said that the failure of a satellite, even one in a plane with no spares, would result in an outage of no more than six minutes because the network is able to compensate through the use of intersatellite links.

Iridium says it has already begun discussing with IMSO a memorandum of understanding that would lead to IMSO oversight of Iridium network performance. Assuming no roadblocks, Iridium says it could be certified for GMDSS services before the end of 2015.

The GMDSS guidelines say providers must guarantee at least five years’ notice before shutting off the service. The British position is that Iridium cannot offer this because its current constellation is at risk of being de-orbited, at any time, by order of the U.S. government.

In its financial filings, Iridium has said that because more than four of its operating satellites now have too little fuel to be successfully deorbited within 12 months, the U.S. government does have the legal right to order the full constellation deorbited to prevent a buildup of orbital debris.

The company has said the likelihood of this happening is remote. The U.S. government, especially the U.S. military, is a large Iridium customer.

The Iridium proposal includes its agreement to provide distress communications services and medical assistance calls free of charge for both the sender and receiver.

In response to SpaceNews inquiries, Iridium on May 30 said, “The only reason our network performance is currently under attack is due to our application as a new entrant into GMDSS communications, which stands to upset the monopoly Inmarsat has maintained in the maritime market for three decades. The International Maritime Organization is the governing body qualified to determine if our network meets these requirements, and that process is currently underway.” 

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Peter B. de Selding was the Paris Bureau Chief for SpaceNews.