“Lunken tower, this is Cessna Eight Eight Uniform, our windshield is covered with oil and we’re returning for an immediate landing.” I’ll never forget making that radio call 14 years ago, and today I can still visualize the oil-soaked windshield as vividly as the day it happened. Even more memorable is how one small, easily-preventable oversight led to this in-flight emergency.

I began my flight training 17 years ago in the fall of 2000 at Sporty’s Academy. Things were a bit different then – the primary trainer at the school was a Cessna 152 that rented for $47/hr. wet, my flight bag was filled with 50 pounds of books and paper charts, and I managed to stick with the same flight instructor from the first hour all the way through commercial and CFI.

Tony, my instructor, was meticulous at following checklists and procedures, a skill that transferred to me well during training. In addition to constantly harping on using the checklist for each phase of flight, he followed his own standard operating procedures as well. For example, he would always visually check the fuel level in both tanks and the oil in the engine after I had completed my own preflight.

During the first few lessons I really didn’t understand why he didn’t believe me after I had already checked everything – why did he need to do it again? I soon learned that was his routine, to check the fuel and oil before for every training flight. Given the importance of both fluids, I welcomed the double check.

Fast forward two years later and I was working in the same role as fresh CFI on the Sporty’s flight line, and naturally incorporated the same teaching methods and procedures I learned from Tony. I checked the fuel and oil before every flight after my student completed the preflight, regardless of their experience level. It took discipline, but as with all checklists and standard operating procedures (SOP), they’re only effective if you consistently use them, no matter how routine the process may feel.

As I gained experience I started working with students who owned their own airplanes at various airports in the Cincinnati area. One of my students recently joined a flying club and I was helping him with a checkout in a 1964 Cessna 206. On this particular afternoon. we had planned to practice landings at Cincinnati’s Lunken Airport – about as routine as it gets. As I walked out to the ramp I observed he had already finished the preflight and was ready to fire up.

I’m not sure why I didn’t follow my procedure of checking the fuel and oil, but for some reason that day I hopped up in the right seat of the airplane and we began briefing a plan for the flight lesson that was about to start. We were parked at the terminal ramp, and after startup, the ground controller issued us a short taxi to the hold short line for Runway Three Left.

After completing the runup and receiving a clearance for takeoff, we enjoyed a brisk acceleration down the runway and rotated at the normal speed. Shortly after liftoff, a dark brown film covered the left 3/4 of the front windshield. OIL! There wasn’t enough runway remaining to abort the takeoff, but fortunately, the airplane was in the proper nose-up pitch attitude and climbing well, and all the engine instruments were in the green.

With the airplane under control, my main concern was the cause of the oil leak – did something catastrophically fail on the engine, leaving us with only seconds of useful life from the engine? Or was it a minor leak from the oil lines leading to the constant-speed propeller causing a big mess? There was no way to know for sure.

I took over the controls from my student, reduced the power during the climb, and notified the tower we’d need to return for an immediate landing. There was a lot of traffic at the airport that day, but the tower controller cleared us to land on any runway and temporarily cleared out the inbound traffic. I flew a tight left pattern and circled back for our departure Runway Three Left.

Established on a close left downwind, all the engine instruments were still in the green and the engine sounded fine, so my confidence was rising that it would stick with us through the landing. I pushed up against the side window from the right seat trying to get a view out the front and found a small opening to help line up on base and final. After an uneventful landing, the controller asked if we needed additional assistance. We declined and taxied back to the ramp.

After shutdown, we stepped out to find the front cowl covered in oil. What the heck happened? My student and I were both thinking the same thing at that point, as we opened the oil door on top the engine to find the cap was not in place on the filler port. We both kicked ourselves for our actions – him for not securing the cap properly after adding oil before I showed up, and me for not following my standard preflight checks of the essential items.

What caused me to stray from my normal procedure? The best answer I can come up with was the variation in airplane and airport environment led me to overlook the basics and assume everything was good to go. The realization set in on the drive home from the airport that this one small oversight could have led to disastrous results if we had lost all forward visibility and couldn’t see out the front. Fortunately, we walked away from the incident with just a few bruised egos and a dirty airplane.

I learned a lot that day and gained a new respect for the importance of checklists and SOPs – use and follow them EVERY time, not just when it’s convenient.