There are many rights of passage for pilots: the first solo, the reciept of the first certificate, the first instrument flight.
My flight instructor used to tell me that you weren’t really a pilot until you had either been stranded somewhere, or taken the bus home. It just so happens that in early January, I found myself stuck in Lancaster, PA.
I didn’t plan to be stuck…
My mission for the day was to have the blind encoder replaced by my friendly avionics shop in Lancaster, PA. The blind encoder determines a pressure altitude and reports this to the transponder, which then reports the altitude to air traffic control.
The flight started off rough, with about an eighth of an inch of ice on the wings and a brutally cold morning. After turning the airplane into the sun and having the engine preheated (it was in the low twenties), I prepared to depart. There was still some ice contamination but enough was removed to make me feel comfortable in the sun’s melting abilities, especially once airborne.
Departing on my IFR flight plan I made my way quickly to Lancaster, cleared direct at 5,000 feet. Lancaster was marginal, and I flew the ILS approach to land. I greased the landing, and taxiied to the avionics shop.
Making good decisions
The job was supposed to take no more than four hours, so with a 9 am arrival time I should have been airborne by 1 pm at the latest.
Unfortunately, nothing is quite that simple when it comes to avionics repair; when the vertical speed indicator was replaced, a leak developed that needed to be repaired to certify the static system. This repair took far longer than expected, and night began to fall.
Not being night current, I had a hard choice to make: attempt a night flight back to Gaithersburg, or stay overnight in Lancaster. With no change of clothes, toothbrush or other equipment, staying overnight was a tough choice, but was the decision I ultimately made. Good decision-making is easy to talk about when presented with a scenario in a textbook, but often very hard when you want to go home more than anything. Still, I believed I was making the right choice.
Good decision-making proved correct
The next morning was foggy and Lancaster was IFR. I filed my flight plan, headed back to the airport, thoroughly preflighted the airplane and prepared to depart into IMC. Reports had visibility at 2 miles and overcast at 400, and a pilot reported he entered the clouds at around 800 feet, picked up no ice, and that the ride down was pretty easy. I was prepared, and ready to go.
With all systems checked I was cleared to depart. Turning onto the runway I applied full power and began checking the guages. Since this is my own airplane I’m quite familiar with how it feels, and at rotation speed I realized the airspeed indicator was not functioning at all. I aborted the takeoff, and taxiied back to the shop.
It turns out that mud wasps had partially blocked the pitot-static system during the summer; the leak in the cabin provided essentially an alternate static system, and the pitot blockage was not severe enough to indicate a failure at all times. When the system was closed again, the outside blockage was now responsible for totally blocking off the system.
Had I attempted to depart the night before I would have potentially departed with a failed airspeed and altitude system. Even though departing into a 400 foot ceiling of fog and poor visibility wouldn’t have been good either, I would have quickly reached VFR and would have been able to avoid obstacles; at night, this is far more difficult (not to mention attempting to land in the dark with an emergency and no altitude information).
My avionics shop is wonderful, well qualified, and thorough. Still, they had no idea or indication of a system blockage, nor should they have; their certification was only for static leaks, not a full certification of the pitot-static system for IFR flight.
The avionics shop always recommends that new installations be checked out in visual conditions, and though my change was minor, I’m lucky I didn’t depart into IMC with a failed altitude and airspeed system.
I also learned that I should trust my judgement. A night departure could have been fatal, and given the lower light conditions I might not have noticed the failure as quickly as I did. Trusting my judgement and staying the night may have cost me a few dollars and been inconvenient, but it sure beats being dead.
Finally, I learned that there’s no such thing as a “quick fix” in the airplane world. My aircraft is 45 years old. Components that were installed 30 – 45 years ago may fail in strange ways, and may require more time than expected to replace. I will not head anywhere for a “single day fix”.