This is one of those embarrassing stories, that quite honestly I normally wouldn't tell too loudly. However it is one that everyone can learn from, so telling it, with only the cost of a bit of ego, has merit. I obviously did not do as thorough of a preflight as I should have. I knew where the static ports were, but not having the recency of experience in this model (I fly about 75-100 hours a month for work) I overlooked them. Wouldn't you know it, this was one time it was important, as they were painted over.
The good news was GPS ground speed is a useful tool in such situations. "Known" pitch and power settings are also useful and they are usually close enough for most small airplanes with similar performance. Having these things, I was quite comfortable, yet cautious, with out airspeed. I was, however, thankful to have Daryl leading to navigate airspace under class B and to provide his mode c services into the MSP mode c veil as a flight.
I also confessed to a few friends who are also professional pilots and told them that clearly I can and need to be more cautious. Even though I fly for a living and have extensive training, we all have the ability to make a mistake, in any airplane, no matter how routine you think the flight may be. Be careful, be cautious, don't get rushed, and by all means FLY THE AIRPLANE.
Pre-flight all instruments were indicating normally. Since we had briefed and were flying a formation departure, I only did a cursory look at the instrument panel on the takeoff roll. When I looked down, I had "some" airspeed, and then kept my sights locked on lead until rejoined. We got on course and I moved out into route formation to look over instruments. I immediately knew what was wrong. Knowing the indications of pitot vs. static port blockage was helpful.
I pondered my situation a bit and once clear of the traffic pattern and on a discrete air to air frequency verbalized the problem to Daryl, as the formation leader. As professional pilots, we are trained to use our outside resources to the maximum extent possible, so I used Daryl as a part of my CRM (Crew Resource Management). We discussed and agreed on the probable cause. We then had a discussion on how to proceed.
At this point I was faced with a choice. Return to the departure airport, or continue. Our original plan was to go to an airport 40 minutes away with cheap fuel, but that airport was unknown to either of us. That airport was immediately out of the question in my mind due to lack of familiarity as well as not knowing for sure if we could fix the problem once on the ground.
I have experience flying small airplanes without reference to any instruments (instructing in the back seat of tail draggers). I was confident in my ability to maintain safe flying airspeed without an airspeed indicator. With a lead airplane of similar performance, I had a qualitative "indication" of airspeed and altitude. I also had groundspeed as a de facto quantitative indication. I judged it safe to continue, but that we should go to the airplane's home base where we would better be able to handle the discrepancy.
