Article written by CFII Brandon NeSmith
We are approaching the middle of summer and I am loving it! I tell all my students that the best times of day to fly this summer is early in the morning and late in the evening. You’ll get the coolest temperatures and the smoothest rides. Thunderstorms are another topic of discussion but what I really want to talk about is aircraft performance and decision making. If you didn’t learn in ground school the 4 H’s affect aircraft performance: High, Hot, Heavy, and Humid!
Recently I took a trip down to Georgia to visit family and decided I wanted to land somewhere more off the beaten path. Lenora Airport (2GA9) is an airport with “character.” It’s a lovely private grass strip just south of Gwinnett County Airport (KLZU) on the Atlanta sectional owned by an old Delta airlines captain Bill Bundrant. I took time the day before my departure to review the usual things, weather, TFR’s, NOTAMs and a friendly call to Mrs. Bundrant to make sure the grass on the runway wasn’t too long and no cows had gotten loose. She cheerfully told me Mr. Bondurant was out of town but I was more than welcome to land and tie down outside. I had been to Lenora before on the ground but this was the first time I would be landing there and thought it’d be a nice gesture to call and announce my arrival.
Flight Manuals for the 1964 Piper Cherokee I’d be flying in aren’t as detailed as the manuals we have today. The manual says for the density altitude I’d be landing with down at Lenora, I would need 1200 feet of runway to clear a 50ft obstacle at the end of the runway and land at gross weight on a paved level runway. Fortunately for me the runway was 2800ft long allowing me plenty of margin of error. But how would I apply correction factors to account that I wouldn’t be landing on pavement, the runway wasn’t level and I wasn’t at gross weight? My personal rule of thumb is to add 20% on to the total distance to clear a 50 foot obstacle when landing on dry cut grass. So now when I was planning to land I needed 1440 feet to land. I had more than double that available, so provided I touched down somewhere in the first 800 feet of runway I had plenty of room to stop. All of this planning before departure led to a smooth landing at Lenora. The family was happy to see me land and we were off to hang out by the pool for the weekend.
Saturday came and went with all the glorious food and cold beverages I could stand to have by the pool. Saturday evening I figured I’d take a look at the weather forecast for Sundays departure and review the takeoff performance charts. The chance for thunderstorms was less than 20% but the temperature on Sunday afternoon would be 90 degrees. Ugh! I would need all 150 ponies to pull the Cherokee back into the air. The performance charts also made me wonder how she would perform. If was flying a brand new airplane in 1964 from a paved, level, no wind runway, at gross weight I would need 2300 feet of runway to takeoff and clear a 50 foot obstacle. But this time I wasn’t taking off from a paved runway I was taking off from grass. Throw my personal 20% factor for the grass and now I was pushing 2760 feet of runway needed to takeoff. Yikes! That’s leaving me only 40 feet of runway to spare! Not wanting to push it that close I elected that maybe it would be safer to leave my other two passengers on the ground first and see what the takeoff performance was like without them onboard. Taking away 200 lbs of passengers decreased my distance to 2500 feet leaving me 300 feet to spare. I told my passengers if I thought the airplane performed well enough I would come back around for a landing and pick them up. If I didn’t like the way the airplane handled I would depart and reposition to a longer runway where I take them from there.
A little known trick to give you maximum power for takeoff in non-tubocharged airplanes, do a full power runup and lean the mixture for maximum RPM. During my before takeoff checks I made sure to do this and it was good for another 50 rpm which made me feel like I was making use of all 150 ponies up front. With 25 degrees of flaps set I taxied the airplane all the way to the end of the runway and kept the airplane rolling. Nosewheel held off the runway, the airplane was in the air before the halfway point of the runway. I accelerated to the best angle of climb speed and pointed the nose upward to clear the obstacles before the end of the runway. Much to happiness I cleared the trees easily by more than 100 feet and climbed above the airport to circle back to land. I shut down and retrieved my eager passengers and repeated the same takeoff technique as before. This time the airplane became airborne just past the halfway point down the runway but I wasn’t worried. I still cleared the trees by the end of the runway by 50 feet and felt good about it. I felt good because I had tested myself and the performance of the airplane just before and knew that I had adequate performance to spare.
So what steps did I take to reduce my risks?
- I familiarized myself with the airport and obstacles by the runway before I departed. Every runway is different and when runways are short you have to take all factors into consideration.
- Weight was a factor that I could control. I elected to make a departure at a lower weight without passengers first to determine how much extra performance I would have available to haul a heavier load later.
- I did my performance calculations before taking the runway. Just because I landed there didn’t mean that I was sure I could get out of there. I looked in the book and looked at what conditions a factory test pilot flew under. After that I applied my own safety factors because I admit, I’m not a test pilot.
- I used proper technique. I know that my takeoff roll would have been SIGNIFICANTLY longer without the use of 25 degrees of flaps. I also kept the nosewheel of the airplane off the ground during the takeoff roll so that the weight of the airplane would transfer to the wings as quickly as possible.
- I put my passengers safety first. In over 20 years of professional flying not once have I had a passenger question me when I told them I was making a decision in the interest of THEIR safety.
If you haven’t been into a short runway or a grass runway in a while call your favorite flight instructor and get them to take you! There are MORE grass runways in the great state of North Carolina than paved runways and with proper planning and technique you can enjoy the pleasure of landing somewhere other pilots may not have been. Till next time fly safe and keep the ball in the middle!