Turning base to final, I saw a Piper Cherokee sitting on the centerline at the arrival end of the runway. "Keep an eye on him," I told my student as we rolled level onto final approach. "Be ready to go around if he doesn't move soon."
The "pop-up": an on-the-spot IFR clearance from ATC, possibly without either an IFR briefing or having filed a flight plan -- it's quick and dirty... and it beats the heck out of scud-running.
Pop Quiz: Is it against the Federal Aviation Regulations to take off with ice and snow on the wings? Will “dry snow” blow off the wings and tail during takeoff? Can you eliminate any takeoff ice hazards by “polishing” frost on the wings until it’s smooth?
Pneumatic systems, while simple, can prove to be difficult to troubleshoot. If you're ever host to a pneumatic gremlin, getting the aircraft back on the ground may be only the beginning of your problems.