An all-party committee of MPs has attacked the Ministry of Defence's handling of the Army's new generation of battlefield radios.
The MoD says no lives have been lost due to problems with the radios
The Public Accounts Committee accused officials of "wringing their hands" as delays and costs mounted.
It also says the digital Bowman equipment weighs too much and does not allow communication with allies.
The MoD said improvements were being made, but it was confident no lives had been lost due to the problems.
But troops on the ground are suffering because the radios still do not have all the capabilities promised, according to the committee.
Edward Leigh, the committee chairman, said: "The Bowman radio packs, despite the repeated concerns of Directors of Infantry, weigh a ton and so can't easily be carried by the infantry in combat.
"And Bowman will not for the foreseeable future have the ability to communicate with our allies - the feature intended to lessen the likelihood of 'friendly fire' accidents.
"These problems must be sorted out," he said.
The committee's report found that no one individual within the MoD had been given responsibility for ensuring Bowman was a success.
There was inadequate preparation for installing the kit on the military fleet of 15,700 land vehicles, 141 naval vessels, and 60 helicopters.
Conservative MP Mr Leigh warned: "This can have disastrous consequences on the battlefield where good communications are quite literally a matter of life and death."
"We have become wearingly familiar with MoD officials seriously underestimating the technical challenge of complex new projects and the resources required, blithely agreeing to unrealistic timetables and wringing their hands as delays and costs mount.
"For any project like this in the future, the MoD must take a much more hard-headed and realistic approach to its relationship with contractors, timescale, the costs over the whole life of the project and capabilities of the system."
Iraq and Afghanistan
Nick Harvey, the Liberal Democrats' defence spokesman, said: "This report tells a sorry story of delay, waste and inefficiency.
"Given the serious risk to our troops from friendly fire, it is particularly worrying that the capability to communicate with allies in the field has been delayed."
Lord Drayson, the Defence Procurement Minister, said the Bowman system was world class and was already proving its worth in Iraq and Afghanistan.
He said: "The committee highlights a number of problems with the Bowman programme over many years.
"The Ministry of Defence has learnt the lessons from these issues and is implementing a reform programme across defence acquisition to improve significantly our performance."