The Royal Navy's plan to fit most of its fleet with command systems based on Windows boxes continues, with the commencement last week of a programme intended to replace the existing commandware of the Service's Type 23 frigates. The Type 23s will make up the majority of the British surface fleet for the foreseeable future.

According to the Ministry of Defence (MoD), HMS Montrose has now entered a planned docking and refit period during which BAE Systems plc will replace her original DNA(1) gear with DNA(2), said to be "based on the system being fitted to the Royal Navy's powerful new Type 45 Destroyers". This means it will be based on fairly everyday hardware running legacy Windows OSes - people who have worked on these programmes inform us that both Win2k and XP will be in use across the fleet.

Along with replacement computers and cabling (12km of new string will be run aboard Montrose during her refit, apparently), the frigate will receive a mid-life update to her Sea Wolf close-in surface to air missile system. This will no doubt be welcome, as it is no longer a secret that the basic system had reached a level of almost total no-confidence among operators as of the turn of the century.

Commodore Graham Peach, the man in charge of looking after surface warships in the MoD purchasing and maintenance empire, hailed the new off-the-shelf IT approach.

"This docking period is an important milestone in our programme to develop a common command system across the fleet," he said. "We have worked closely with the contractor, BAE systems, to develop DNA(2) and its sister systems which will enable us to provide more efficient support to the fleet, simplify operator training and deliver cost savings in the long term as servicing is required."

According to the MoD, BAE will "develop a common command system across the fleet" for just £30m under a contract awarded in 2006, perhaps putting an end to decades of horrifyingly frustrating intership networking problems. Anyone like your correspondent who has served at sea in the last ten years will recall the use of embarrassing expedients such as reading endless strings of figures across voice channels (often enough civilian mobile phones or marine VHF) or re-keying them from hardcopy printouts into another machine in the same ship.

In addition to the frigate and destroyer fleets, the Navy has recently announced conversion to Windows in its submarine flotilla. It is also understood that the new aircraft carriers, whenever they arrive, will also use similar commandware. It would seem that one large customer at least isn't having any of this Vista/7 malarkey, certainly not for the foreseeable future.

Many in the software community have criticised the Navy's moves, feeling that Windows cannot offer the sort of guaranteed reliability one might wish to see in computers which will sometimes have direct control of powerful weapon systems - and on which Blighty's fighting matelots may one day depend for their lives. However, one ought to note that the preceding custom solutions were usually so terrible that a reasonably stable Windows box would actually be a serious improvement. Furthermore, it is fairly rare in naval combat for there to be any need for "man-out-of-the-loop" operations.

The only common situation where weapons need to be fully autonomous is that of surface ships defending against sea-skimming missile attack, which calls for extremely fast reactions based on limited information. Existing Phalanx and Goalkeeper auto-gun systems are already commonly switched to autonomous operation as missiles close in - or are thought to be closing in - and this is also done in such situations with American Aegis firecontrol systems in charge of Standard interceptor missiles.

If the new Type 45s ever find themselves trying to beat the dreaded supersonic sea-skimmers of the future to the punch - and if they never do this, they will not have been worth buying: they can't do anything else you might pay a billion quid per ship for - they will need to let their command systems shoot instantly at any fast, close low-altitude track which appears in the command system. A human, if in the loop at all, will not have time to add anything to the decision-making process.

So yes, there will be scope for errors; but this is more a problem of surface-based air defence than it is one of OSes. The danger presented by a combat ready air-defence destroyer in what it considers to be a threat zone would probably exist no matter what software it was running.

Given that the Navy will have its warships anyway, UK taxpayers might at least be pleased at the prices the Service seems to be paying to have its commandware replaced. Again, regular IT people won't be terribly impressed at fairly small numbers of fairly humdrum platforms being replaced for tens of millions of pounds: but in the context of traditional warship computer programmes the ongoing MoD projects are actually looking pretty good.

Whether that's adequate compensation for the possible attendant security and reliability issues will remain a matter of opinion for a while - until the new war-Windows platforms start seeing widespread, networked-up service. ®