intubation is a procedure that paramedics are normally authorised to perform.
No - a paramedic (UK) can only carry out an intubation if the patient is GCS3 - ie non responsive. An RSI requires the use of paralysing drugs that only a doctor can administer or be given under their supervision.
Why couldn't intubation be performed while airborne?
Too much noise, vibration and lack of space. A controlled RSI requires the doctor to be behind the patients head using the laryngoscope to position the tube.