Aviation In Canada

Friday, April 29, 2005

Use of "Clear" by Ground Control

I was born and raised as ATC in the tower at Halifax International Airport in Nova Scotia (CYHZ). They guys there are a great bunch. Learning the ropes, I found there were all kinds of little things, and each one of them had their own little bit of background.

For example, there is written direction to avoid the use of the word "clear" on ground frequency. It soon becomes "clear" why, too, if you try it. You have vehicles out there doing snow removal. You have traffic is coming, intending to use the runway they're on. So you get them to "clear the runway". Someone out there says to himself, "What the heck does he think I'm doing? Of course I'm clearing the runway!" Or, a new trainee on VatSim that I worked with the other night, while trying to get an aircraft to "backtrack to position on runway 15," at CYHZ, used the phrase, "cleared on to runway 15, backtrack to position." While discussing with the trainee that it was not allowable to use the word "cleared" on the frequency outside of a take-off or landing clearance, he told me he didn't understand why. Sure enough, the pilot backtracked to position, turned around, and took off. He had misinterpretted the clearance as, "cleared for take-off runway 15, backtrack is approved."

It seems so inocuous, like nothing could go wrong. But then, that's how things like this are discovered. "I can't believe he did that," from one side of the radio can turn so quickly into, "that's what he told me to do," on the other end. Fight about it all you want, but it's often one little word that makes the difference between a successful operation and something unplanned ruining your day. And this is why we have a number of official phraseologies in aviation.