Coastguard rescue helicopters from both Lee-on-Solent and Portland have joined Yarmouth RNLI in the search for the twin-prop aircraft in the waters surrounding the iconic landmark.
A member of the public raised the alarm shortly after 12:15 this lunchtime while observing the plane from the National Trust Old Battery.
Police have joined the Needles Coastguard team in their investigation into the incident at the observation point at the former High Down rocket test facility.
UPDATE @ 14:10
Solent Coastguard have confirmed that the search and rescue operation for the ditched aircraft has been called off after it is understood the member of the public who reported the incident had got confused with a white boat on the horizon.
The aircraft at the centre of the frenzied confusion has been tracked to an airport in Alderney where it landed safely.