The Guernsey States-owned airline has also received the first of its Dornier 228 planes to replace the trislanders currently operating the route.
Aurigny has been criticised for problems with the trislanders causing delays and cancellations to flights.
Mark Darby, chief executive officer, said the Let 410 would be used while training took place on the Dornier.
He said it was to "see us through the introductory period of the Dornier and to provide an additional aircraft in the event of the trislanders needing any maintenance'.
The Dornier 228 is the first of two being leased from Portuguese airline, Grupo 7.
Mr Darby said the delay in the Dornier's arrival was a "frustrating experience", but added a "vital technical modification needed to be made" to improve the plane's reliability in all weathers.
He said the Dornier was faster than the trislanders and should cut 15 minutes off flight times to Southampton and could carry 19 people, three more than the trislanders.
Mr Darby said the intention was to have three Dorniers in place as soon as practical.
He said the change would have no impact on the medivac service the company provides.
Aurigny has brought in an extra plane to provide more security for flights to and from Alderney.