An ambulance driver on a 999 call left a girl with "life-changing" injuries after crashing into her car as he tried to overtake it, a court has heard.
Andrew Collis's driving fell "far below" standard as he drove to a crash on the A32 at Mislingford, Hampshire, and hit a car he tried to overtake.
The driver, Jessica Barnett, 18, has remained in hospital since the crash.
Mr Collis, of Limetree Close, East Preston, West Sussex, denies one count of dangerous driving on 9 February.
Portsmouth Magistrates' Court heard how Ms Barnett's Renault Clio had stopped and was indicating to turn right into Buddens Lane.
She then stopped flashing her indicator and drifted back into the middle of the single-carriageway.
Sophie Stevens, prosecuting, said that at this point Mr Collis, of South Central Ambulance Service, decided to pull out into the oncoming carriageway with the intention of overtaking Ms Barnett's car.
But within moments, the Clio's right indicator flashed right again and the two vehicles collided.
The accident happened at about 1830 in dark, drizzly conditions.
'Both at fault'
Ms Stevens said there was no suggestion of Mr Collis driving above the 60mph speed limit or that a mechanical fault or mobile phone use contributed to the crash.
She said: "This is clearly a case where Mr Collis's actions alone will have to be considered.
"The crown says that the manner of Mr Collis's driving fell far below the standards of a competent and careful driver," Ms Stevens added.
Mr Collis's colleague, Daniel Major, said Mr Collis was driving the ambulance with its blue lights and siren on in an appropriate way and he felt there was nothing he could have done to avert the crash.
The impact of the crash caused Miss Barnett serious head injuries, from which she is still recovering in a specialist unit at hospital in Bath.
Pc Victor Plasins said both drivers were at fault for the collision.