the flag symbolizing the letter G in the International Code of Signals, flown by itself to request a pilot from a pilot service: a flag of three yellow and three blue vertical stripes.
the flag symbolizing the letter H in the International Code of Signals, flown by itself to indicate that a pilot is on board: a flag with one white and one red vertical stripe.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Examples from the Web for pilot flag
Some five hundred yards beyond the barrier, a small Danish steamer flying a pilot-flag, came steaming towards us.Gun running for Casement in the Easter rebellion, 1916|Karl Spindler