Another innocent person could be shot dead by police in the future, the senior officer who led the operation which ended in Jean Charles de Menezes's death told his inquest today.
Deputy Assistant Commissioner Cressida Dick said police set out to reduce the risk to the public.
But she admitted this could only be done to a "less than perfect extent" when terrorists were on the run, making possible a repeat of the events that culminated in the Brazilian's death.
Mr de Menezes, 27, was shot seven times in the head at Stockwell Tube station in south London on 22 July, 2005 after being mistaken for failed suicide bomber Hussain Osman.
Ms Dick was in charge of the Scotland Yard control room overseeing the pursuit of the Brazilian electrician by surveillance and firearms officers who feared he was the terrorist.
Michael Mansfield QC, counsel for the de Menezes family, asked her if the fatal shooting could happen again.
Ms Dick replied: "I'm afraid, sir, I do believe that this or something like this could happen again.
"The nature of these operations is that they are incredibly high risk to all concerned.
"And that is because of the nature of the threat that we face from suicide terrorists, and the difficulty that there is in dealing with such a threat and the very fast timescale in which these things can happen.
"Our job is to reduce the risk to everybody as best as we possibly can all the time. That is what we set out to do.
"But I do fear that in the future a bomber might not be prevented from setting a bomb, and there would be a huge scrutiny of why we did not manage to prevent that.
"And equally, I pray it doesn't happen, but it is possible that an innocent member of the public might die in circumstances like this.
"Our job is to minimise the risks. Given the huge scale of the risks, we may only be able to do that to a less than perfect extent."
Mr Mansfield alleged that police were "sprinting to catch up" throughout the morning of 22 July because the manhunt for Osman and the other bombers had not been properly organised.
The inquest heard that Ms Dick told another senior officer at the end of the day that the first hour of the operation had been "appalling".
The policewoman said she was referring to the lack of structure which is common in the early stages of responding to unplanned major incidents.
Mr Mansfield asked her: "Are you telling the British public that the average big operation starts with an appalling structure?"
Ms Dick replied: "You can't get everything in terms of planning right immediately so there is always a period of needing to get the structure right."
The Menezes family's barrister put it to her: "Essentially from the beginning you were sprinting to catch up with something that had not been properly organised that morning."
Ms Dick answered: "I follow it, I do not accept it."
The senior policewoman also denied that either Scotland Yard or she personally had a problem with admitting that things went wrong.
She told the inquest: "I regard myself as somebody who will always take full responsibility for what I have done.
"I will be quick to say if I think I have done something wrong."
Ms Dick said she was not surprised to learn that two specialist police marksmen had fired nine or 10 shots at Mr de Menezes's head.
Mr Mansfield asked her how she reacted when the firearms team commander told her this.
She answered: "I don't think I had any reaction, sir. He was giving me information. I was not surprised."
The inquest heard that early on 22 July a senior officer, identified only as "Alan", ordered a firearms team to go to a block of flats linked to Osman in Tulse Hill, south London, but this did not happen.
In the event Mr de Menezes walked out of the same block, where he was living at the time, and was allowed to enter Stockwell Tube station before he was intercepted by armed police.
Mr Mansfield asked Ms Dick about the firearms team's apparent failure to deploy to the scene.
He said: "I am going to ask you - I'm afraid it will be a repeated theme - there were serious breakdowns in communication at the very least on that night."
She replied: "I don't know that, sir... If that is what happened, then that sounds like a miscommunication."
The senior policewoman also spoke about the difficulties Scotland Yard faced the day after London's transport network was attacked for the second time in a fortnight.
Ms Dick said: "The whole operation was very unusual. We had never dealt with anything like this before."
She added: "I want to explain what it is like in the thick of setting something like this up.
"You simply can't magic up all the people to do all the jobs that you want out of thin air immediately.
"You do your very best to get the right people in the right seats, properly briefed, doing the right jobs."