A jury has seen CCTV footage said to show the moment one of the men on trial over the alleged 21 July 2005 bomb plot tried to set off a device on a bus.
Muktar Ibrahim is accused of trying to detonate a homemade bomb on a number 26 bus in Shoreditch, east London.
A park-keeper also told Woolwich Crown Court how he found a bomb allegedly dumped by Manfo Asiedu.
Mr Ibrahim, 29, Mr Asiedu, 33, and four other men deny conspiracy to murder and conspiracy to cause explosions.
Muktar Ibrahim, 29, from Stoke Newington, north London
Ramzi Mohammed, 25, from North Kensington, west London
Yassin Omar, 26, from New Southgate, north London
Hussein Osman, 28, of no fixed address
Manfo Asiedu, 33, of no fixed address
Adel Yahya, 24, of High Road, Tottenham, north London
The other defendants are Hussein Osman, Ramzi Mohammed, Yassin Omar and Adel Yahya.
Mr Yahya is accused of helping to plan the alleged attacks while the others are all said to have set out on 21 July 2005 to carry out suicide bombings London's transport network.
But the prosecution claimed Mr Asiedu "lost his nerve" and left his bomb in Little Wormwood Scrubs Park, west London.
Bus driver Mark Maybanks told Woolwich Crown Court he heard a "loud bang" and thought another vehicle had hit him.
Mr Maybanks said he found a rucksack on the floor on the top deck of the bus with the alleged explosive mixture of hydrogen peroxide and chapatti flour "oozing out of the sides".
"I have never smelt anything like it before," Mr Maybanks told the court. "It was definitely a tainted smell, something that is not right on a bus."
Mr Ibrahim is alleged to have tried to set off his bomb shortly after 1300 on Shoreditch High Street, near the junction with Hackney Road.
The CCTV footage played in court showed passengers on both decks of the bus suddenly turning in their seats at the sound of the bang.
The film showed the man said to be Mr Ibrahim then abandon the rucksack near his seat at the back of the top deck and climb down the stairs.
The remains of the alleged device were found on the top deck
Mr Maybanks, who had stopped the bus in the middle of the road, opened the bus doors and walked to the back to check for damage.
It was at this point that Mr Ibrahim is said to have left the vehicle and fled the scene.
After establishing there had not been collision, Mr Maybanks drove to a bus stop.
Mr Maybanks said he climbed the stairs to the top deck and noticed several screws - alleged by the prosecution to have been packed around the bomb.
Mr Maybanks said Mr Ibrahim had caught his attention when he got on the Waterloo to Hackney Wick bus near Bank station.
"It was the way he boarded the bus that makes it stick out in my mind," he said.
"This particular gentlemen was waving the bus pass in a funny kind of manner and made staring eye contact with me."
The jury was also read a statement from a passenger who had fallen asleep on the top deck of bus.
Security officer Abu Kamara, said he was "woken by a big bang".
21 JULY 'BOMB PLOT' TRIAL
Map of London showing key locations of prosecution case
He added: "I was very shocked and didn't know what was going on. I could smell something burning.
"The bang that I heard sounded like a handful of marbles or glass being dropped from a height on the floor."
Det Con Graham Innes told the court that Mr Ibrahim's DNA was found on a battery alleged by the prosecution to have been part of the bomb.
Later, park keeper Jackie Whitcomb described how he came across one of the alleged homemade bombs in shrubbery two days after the alleged failed attacks.
Mr Whitcomb said the white top of a container "stuck out quite a lot".
"I saw the nuts and bolts on it and slowly put it down and briskly walked away," he said.
The trial was adjourned until Tuesday.