A third safety issue on the tarmac at Sydney Airport in recent weeks prompted the nation's air safety boss question why investigators were not notified for four days about another incident on Sunday.

The Australian Transport Safety Bureau is investigating a previously unreported incident involving Virgin Australia and Qantas planes cleared for take-off.

A third safety issue on the tarmac at Sydney Airport in recent weeks prompted the nation's air safety boss question why investigators were not notified for four days about another…