It can get boring on test flights. Hours spent quietly winging it from point A to point B with no other purpose than testing out a new engine.

But then inspiration strikes. For one pilot, that inspiration was to use the Mid North as his own personal canvas to voice how boring test flights can get.

Written in letters dozens of kilometres long, the pilot spelt out the words “I’m bored” during a return flight from just north of Port Broughton.

The pilot, who is understood to be a recently qualified instructor at Flight Training Adelaide, left Parafield Airport in a single propeller Diamond Star plane at 8.53am on Tuesday, taking a circuitous route north.

He had been tasked with running in a new engine by flying at a particular power setting for two hours in preparation for the plane to be bought online as an instructional aircraft.

While travelling north the pilot drew some intriguing, somewhat phallic symbols along the coast.

But on the way back the pilot left his message above the Princes Highway, only visible to those watching live flight tracking programs and websites.

The plane landed back at Parafield Airport just after 12pm with the pilot presumably going off to do something more interesting, like their taxes.

Flight Training Adelaide director Pine Pienaar said the pilot’s actions were not condoned and that “apparently he got bored”.

“Young instructors, what can you do?” Mr Pienaar said.