Passengers on a plane were left in shock after their aircraft was involved in a startling collision just as they were preparing for take-off.

United Airlines Flight 1871 collided with another plane on the runway at San Francisco International Airport on Monday, causing a jolt to passengers as it backed up to a gate at the major US airport. The Federal Aviation Administration (FAA) confirmed that the Denver-bound plane struck another United aircraft around 9.10am.

Flight 1871, a Boeing 737, hit the tail of the parked Boston-bound Flight 796, which was preparing for take-off at the time. This forced the airline to evacuate terrified passengers and continue the flight with a new aircraft. The news comes as a Brit caused airport chaos by taking woman's child, 4, after 'God told her to'.

Despite the terrifying ordeal, United Airlines stated that passengers aboard both planes were "deplaned normally" with no injuries reported. Passengers have since shared their shocking experiences of the collision.

One traveller revealed they were en route to Boston when the incident occurred, stating they were "in the middle of boarding" when the plane "shook". They added that flight attendants instructed them to deplane as one of the pilots announced they'd been hit, reports the Mirror.

They further commented: "FAs told us to deplane and one of the pilots said we'd been hit. Seems like United ground crew is having a tough year."

Another passenger, who was headed to Denver, described feeling a "big shudder" when the planes clashed, but noted that passengers were "all buckled up".

They revealed: "We were in D16, so they backed us out, down the taxiway, then pulled a big U turn to get us facing forward. Near the end of the U-Turn apparently the tug connection broke, and instead of continuing to turn, the plane just kept going backwards at an angle and hit UA796 (SFO-BOS) which I believe was at E5."

However, the collision wasn't the only mishap San Francisco International and United had to deal with on Monday. A separate flight bound for Baltimore had to make an unexpected return to the airport due to a burning smell detected aboard Flight 2664.

The airline confirmed that the decision was made "to address a plastic burning smell" and the Boeing 737 Max 9, carrying 164 passengers, was brought back to land after it took off around 9.47am.

United assured that all passengers onboard were safely evacuated from the aircraft, and a replacement flight was promptly arranged.