Question:
At work there was a truck parked out back. I was suppose to drop the trailer and pull the tractor out. I put the landing gear down, disconnected the air lines. As I took off the emergency air line, I got greeted with a blast of air to the face. Looked in the cab and sure enought the trailer parking brake knob was pushed in. Now on I'm going to check to make sure both parking brake knobs are pulled out before disconnecting the trailer.

Answer:
In this situation, you will get blasted until the tractor protection valve cuts in.
If it doesn't, it means the tractor has a faulty TPV.

Answer:
I wouldn't worry about doing that. It happens to all of us at one time or other on TT's we are driving and swapping trailers. I do it too!!

Answer:
Just wait until the day comes when you are in the process of unhooking a trailer and something majorly distracts you in the middle of your routine and you go and jump in the seat pull out and look in your mirror just in time to see the air lines go pop because you forgot to unhook them. Now talk about feeling about an inch tall.
Answer:

The pop isn't so bad, it's the loud "S-M-A-C-K" they make bouncing off the back of the cab. And then there is that embarrasing call to the shop to get the gladhand and/or pigtail connector replaced.
-JHappy Dwellers Society
Company Driver Division

Answer:
It could be worse... one could "forget" to drop the landing gear before pulling out.
I

Answer:
A month or so after I began driving T/T's I found what I thought were locked up trailer brakes on a trailer I was picking up one night at the end of my shift.. I tapped on drums. I adjusted springs. I rocked back a nd forth. Nothing worked. They wouldn't break loose. I called in and road service came out. They guy got out, looked around for a couple minutes, gave me a dirty look, and switched the air line glad hands on the tractor to the correct trailer couplings, and quietly got back in his truck and drove off ....
Check everything, even if you think you are doing it right automatically, without paying attention; you can get into a going through the motions mindset, and screw up without ever realizing it, and get embarrassed real easy.
Answer:
uturn2001, Air lines/pigtail slamming against the back of the tractor.
That's happened to me too years ago. You get in a hurry, get distracted, Sh$t happens. Some drivers have forgot to roll down the landing gear. It happens.
Make a habitual routine in disconnecting your rig. What ever routine "you" decide on, make it a habit. Switch habits and that's usually when you'll make mistakes.
Good driving skills are are matter of developing good habits and stick to them.
Remember this, never sweat the small stuff. Just put it in memory as a leaning experience. I've been driving straight trucks and semi's since 1981 and I'm still in learning mode.

Answer:
The guy that trained me to do trailer switches told me to ALWAYS do the same thing when dropping and hooking. Never stray and you will never have a problem.
4 years later, an "official trainer" retrained me. Within 2 weeks of retraining, I had pulled off one brake line (got distracted by the plow guy in the lot) and dropped another trailer without cranking down the landing gear. And a new boss had started and he wanted switches done FAST.
My original trainer reminded me of doing things the way I had always done them and that if anyone interrupted me, to go back to the beginning of the drill. What really bugged me, is that it was soooo easy to develop a routine, I was doing 7-9 drop and hooks in less than 5 hours. It was surprising how fast "retraining" could wreck that routine.
Knock on wood, haven't screwed up since.
Tom B