The coroner in charge of the 7/7 inquests criticised emergency services bosses today for using too much jargon.
Lady Justice Hallett said some terms were so cumbersome and complex that one 999 worker might not know what a counterpart did when arriving at an emergency scene.
On the hearing's final day and bringing five months of evidence to a close - with a verdict expected at a later date - Lady Justice Hallett let fly at Gary Reason, assistant commissioner of London Fire Brigade.
She spoke out as mention was made of "a conference demountable unit from a management centre" - which is a portable incident room.
She said: "As far as I can tell, management jargon is taking over organisations and perfectly sensible, straightforward titles are being changed.
"This isn't just somebody being pedantic about the use of English, which it appears to be... when it comes to managing incidents, people don't understand what the other person is."
The coroner said the problem had been an ongoing theme in hearing evidence.
She said: "I don't know whether a crew manager is somebody who is responsible for supplies or is used to fighting fires. I have no idea."
She added that clarity was key when crews were trying to ensure safety at a disaster scene, saying: "What worries me is all you senior people of these organisations are allowing yourselves to be taken over by management jargon and, as I say, it's not just directed at you... I just think that you people at the top need to say we have to communicate with people in plain English."
Her comments caused laughter in the courtroom after months of listening to the coroner stop witnesses to explain acronyms and specialist terms.
She finished off: "So if you could do anything when you meet up with your fellow senior officers in whatever organisations to encourage the use of plain English, I, for one, would be enormously grateful and I think it would make everybody just that little bit more effective."
It is the seventy-third day of evidence today into the deaths of 52 innocent victims killed on July 7 2005 by fundamentalist Mohammed Sidique Khan and three accomplices on London's transport network.
Though the inquest's evidence finishes today, there will be a wait before verdicts.
Two days have been set aside for legal argument on March 10 and 11.
This will give concerned parties a chance to say something about the evidence and the scope for verdicts.
The coroner will then retire.
Lady Justice Hallett has not indicated how long it will be before she comes back to court with verdicts though it is expected to be before April 20 when the court rises for Easter.
Today Mr Reason, the penultimate witness, focused largely on the fire brigade's actions at King's Cross.
The inquest had already heard there was a delay of nearly 30 minutes in getting firefighters into the station and that they delayed, thinking there could be a chemical or biological attack below, despite travellers emerging showing no signs.
Hugo Keith QC, counsel to the inquest, criticised the lack of trust between emergency services who spent time separately checking there was no biological or chemical attack.
He asked if the tannoy system could have been used to announce it was safe to go below ground.
Mr Reason said: "If the command structure is working correctly as it is designed to do then the associated resources will get a briefing about those hazards," and "firefighters and other agencies will be deployed accordingly."
Mr Keith said the point was that on 7/7 many of the "incident commanders" could not find one another to discuss the issue.