British Airways flights have been "grounded" following a major IT meltdown, resulting in chaos for "thousands of passengers".

The glitch has meant that planes are unable to take off and phone lines are down, whilst pilots have been unable to upload documents containing vital information required to fly safely.

Planes cannot be flown by pilots electronically and must now be operated manually, The Times has reported.

Queues are reportedly building at Heathrow Terminal 5 due to the problem, the outlet reports.

British Airways has been impacted by a major IT meltdownGETTY

Meanwhile, the BA website is currently unable to load, with a welcome text reading: "We are experiencing high demand on ba.com at the moment. Thank you for your patience."

Disruption was first reported by passengers at around 5.00pm, however there was some reports of issues online prior to this.

Pilots are understood to have been informing passengers as best they can, however, crew members are as much in the dark as passengers.

'Load sheets' uploaded by pilots have been unable to be completed thanks to the issues. The documents calculate the weight and distribution of passengers, cargo and fuel.

They are used to calculate performance and efficiency so are essential to flight safety.

There is yet to be any statement or update given out by BA.

Disgruntled passengers have taken to social media to vent their annoyances.

One user said: "Absolute shambles three flights cancelled this month and now being made to stand on the tarmac in a very cold Verona waiting for an already delayed flight. What has happened to the nations airline? Not fit for purpose."