The first near miss between passenger plane and a drone has been investigated by air safety inspectors.
The UK Airprox Board will publish its findings on Friday following the incident at Heathrow Airport.
The owner of the drone has still not been identified raising fears over the potential risks drones could pose to commercial airlines .
The incident is expected to be recorded in the report with a risk rating A, defined as a serious risk of collision, which is the highest of five categories.
The report, seen by the The Sunday Times, said the pilot of the Airbus A320 spotted the drone, which failed to show up on air traffic control systems, at 2.16pm on July 22 while flying at an altitude of 700ft.
Earlier this year the airline pilots' association Balpa demanded better protection for the public against the risks of drones.
It wants drones, officially known as Remotely Piloted Aircraft Systems (RPAS), which share airspace with passenger and freight airliners, to meet the same safety standards as piloted aircraft.
This would include only being flown by operators with pilot-equivalent training.
Heathrow Express workers have started a 24-hour walkout over pay and jobs this morning.
Trains between the airport and Paddington are expected to be disrupted until the early hours of tomorrow morning.
The RMT Union announced the decision following a nine to one vote in favour of action.
Boris Johnson has recruited a US mayor to boost his campaign to close Heathrow and build a new airport in Kent, writes Simon Harris.Read the full story ›
ITV London today revealed Boris Johnson plans to spend an extra £2m on lobbying for a new airport in the Thames Estuary. The mayor has already spent over £3m of London taxpayer's money in an attempt to persuade government that his plan should be taken forward.
Dr Onkar Sahota, Labour London Assembly for Ealing & Hillingdon said his plans could create 'economic chaos' for his constituents in Hillingdon and Ealing.
His plan is unworkable, unrealistic and unaffordable. “His plan for a new airport would wreck west London’s economy and create economic chaos for my constituents in Ealing and Hillingdon.
We do need to make sure that Heathrow works for local residents, this means no ‘mixed-mode’, no additional night flights and different flight paths to reduce noise.
These are sensible workable policies that will make a difference and maintain jobs and the local economy.”
The cost to London council taxpayers of promoting the controversial "Boris Island" airport scheme is to almost double to £5m.Read the full story ›
The Mayor of London is proposing to spend billions of pounds of public money to forcibly buy and then close Heathrow, immediately putting 112,000 people out of work. He would do this to build an expensive new hub airport at a further cost of £112bn to the taxpayer. The economic impacts of this at both a national and regional level would be devastating.
Mayor says he is "always optimistic" the airports' commission will eventually back an estuary airport. @itvlondon
Mayor says the estuary airport has not been ruled out after the idea "was plucked from the waste paper bin" @itvlondon
Mayor Boris Johnson has laid out his plans with Hillingdon Council leader Ray Puddifoot this morning.
Options for the new area include named like Heathrow City, Heathrow Park and Heathrow Gardens.
The Mayor's idea for Heathrow City would include 80,000 homes and create 90,000 jobs. The terminals would be shopping centres.
Hillingdon's options include a London City-type airport to the north west of Heathrow.