The “H” in HAT
As I line up for takeoff on the runway, the first thing that I do is to take care of the H (for Heading) of the HAT check to insure that the runway heading, my compass, and my directional gyro are all in agreement. If any one of the three is in disagreement, then there is definitely a problem that needs to be resolved prior to applying takeoff power. Failure to do so might gain you an appellation similar to one gained by a Mr. Corrigan, numerous years ago.
I know that I am not the only pilot who has announced, as I back-taxied on the runway of a small non-towered airport: “Boondocks traffic, Super Cruiser back- taxiing runway 29”, as I eagerly set my DG to 290 ̊ so as to minimize my time prior to takeoff. Of course the only problem was that I was heading 110 ̊ as I did all of this.
The only thing that saved me that late afternoon, as I took up an easterly heading after departure (according to my DG) was that the sun was shining directly in my eyes. Something was obviously wrong. In this somewhat humorous (and embarrassing) anecdote, the only thing injured was my ego.
But when we are operating at a busy airport, with multiple runways, and kick up the ante even more by adding nighttime to the mix, there is no doubt whatsoever, that insuring that your DG (or H S I), your compass, and the runway heading are all in agreement, will lead to greater longevity as pilots.