A visit to a grass strip in early spring teaches valu­able lessons


Flying - - CONTENTS - By Robert Hanrahan

It was a chilly March day in New Jer­sey, but the tem­per­a­tures were fi­nally ris­ing above freez­ing on a reg­u­lar ba­sis. Signs of snow had all but van­ished, and we CFIs at the flight school were look­ing for­ward to the start of spring and bet­ter fly­ing weather.

On my sched­ule was a pri­vate pi­lot with whom I would oc­ca­sion­ally meet for a re­fresher flight. As al­ways, he re­served our Piper PA-28 War­rior for a two-hour block of dual in­struc­tion. Though legally cur­rent, my client didn’t fly of­ten and was a rel­a­tively low-time pi­lot. Be­fore head­ing out, we es­tab­lished a plan, which in­cluded per­form­ing stalls, steep turns and emer­gency pro­ce­dures be­cause he thought those were the ar­eas where he had the least re­cent ex­pe­ri­ence. I sug­gested some take­off and land­ing prac­tice, in­clud­ing soft- and short­field work.

We flew to our usual prac­tice area and cov­ered the air­work be­fore I pulled the throt­tle well above the nice lit­tle air­field with its short run­way at Aeroflex-An­dover (12N). He did a good job with his en­gine-out and short-field pro­ce­dures. As we de­parted back to­ward Es­sex County Air­port (KCDW), I asked if he had done any ac­tual soft-field land­ings. He replied that he hadn’t, but had al­ways wanted to try.

I di­rected him to­ward nearby Trinca Air­port (13N), a 1,920-foot grass strip that I vis­ited many times over the years. I had him fly over the field, and we took a good look at the run­way, which ap­peared clean and solid. I ob­served no signs of wa­ter or mud, and the turf ap­peared to be in good shape. Though I un­der­stood the risks of soft fields af­ter the win­ter, I had more than a thou­sand hours in PA-28s and felt very com­fort­able with soft-field take­offs and land­ings. Up to now, that is.

The wind was from the west, so we flew the pat­tern for Run­way 24. The ap­proach went as planned. We flared with a lit­tle power and gen­tly placed the mains onto what now ap­peared to be a sur­face that was softer and wet­ter than I’d thought. Dur­ing the roll­out, I re­al­ized the turf was in bad shape in some ar­eas and I be­came con­cerned about the pos­si­bil­ity of get­ting stuck.

I re­al­ized that we needed to get out of there or risk need­ing to make a call back to my boss ex­plain­ing that his air­plane was stuck in the mud. I took back the con­trols and ex­plained that I would be turn­ing the air­plane around for back-taxi and to pre­pare

for take­off. I ex­plained that I would demon­strate the take­off tech­nique, so I set the flaps at 25 de­grees and tax­ied around patches of mud as I headed to the run­way thresh­old. I made a 180-de­gree turn and pointed the air­plane at what ap­peared to be the firmest and dri­est part on the strip.

I ap­plied full power and added back-pres­sure on the yoke, re­sult­ing in bumpy ac­cel­er­a­tion as the gear splat­tered mud all over the front of the air­plane. As ex­pected, ac­cel­er­a­tion was slow, and though the air­plane was at­tempt­ing to lift into ground ef­fect, the patches of mud were caus­ing much re­sis­tance, hold­ing the air­speed be­low what was needed to get us off the ground. As I tried to nudge the air­craft into ground ef­fect we would lift slightly, with the stall in­di­ca­tor sound­ing, yet any con­tact with the sur­face would im­me­di­ately re­duce air­speed and lift. We were in a re­gion where the air­plane was sim­ply not gain­ing enough speed for con­stant level flight in ground ef­fect, oc­ca­sion­ally touch­ing the muddy turf sur­face, which in turn re­tarded the air­speed.

We were in a win­dow where the air­speed would al­low a lit­tle lift yet not enough to stay out of the mud. Too high an­gle-of-at­tack or a lit­tle too much al­ti­tude and the plane would lose lift and splash down into the mud. Know­ing that this could turn into a dan­ger­ous por­poise down the field, I con­tin­ued to search for the small AOA win­dow (which must be re­duced as air­speed climbs), which would per­mit enough ac­cel­er­a­tion in ground ef­fect to al­low for a safe liftoff.

Af­ter pass­ing the half­way mark, I re­al­ized we were beyond the safe abort point. We would clearly not be able to stop be­fore hit­ting the tree line ahead. I had no choice but to con­tinue and gain the nec­es­sary air­speed.

As the air­speed in­di­ca­tor bobbed up and down be­tween 40 and 50 knots, my left-seat cus­tomer started in­sist­ing we abort, but I knew that would have re­sulted in a guar­an­teed dis­as­ter and I felt I was start­ing to main­tain con­trol in ground ef­fect and the ASI was trend­ing up­ward. The stall in­di­ca­tor was still sound­ing, but I now had the air­plane solidly off the turf and the ASI was ris­ing over 50 knots. My client now abruptly im­plored “Climb!” As we watched the tree line straight ahead get­ting larger, I replied with a solid “Not yet!” I am sure it looked very con­cern­ing, and maybe down­right ter­ri­fy­ing for my client, but I knew that we had to main­tain the air­craft in level flight just above the ground (with the trees in the wind­shield) un­til we ac­cel­er­ated to just be­low Vx.

At about 60 knots, with a silent stall in­di­ca­tor (fi­nally!), I gen­tly ro­tated to best an­gle pitch and we climbed over the trees at Vx, clear­ing the tree line by around 300 feet, much too close for this non­bush pi­lot. With sweaty palms, I turned the yoke to head to­ward home. I ex­plained all was OK, and we would dis­cuss the de­tails of our har­row­ing de­par­ture once we got back to the flight school.

Back on the ground, I parked the air­plane next to a wa­ter hose to al­low me to later clean off the mud-cov­ered air­plane. It was a mess!

I de­briefed with my client and re­viewed a few of the things we learned on the flight. I ex­plained (and con­firmed) that soft-field per­for­mance is far from an ex­act sci­ence, and in many cases the ac­tual run­way re­quire­ment for take­off and land­ing is not only un­known but some­times im­pos­si­ble to judge. I ex­plained that I was wrong to at­tempt land­ing at this or any turf field with­out a re­cent first­hand re­port on the run­way con­di­tions, which in this case would have com­pletely al­tered our de­ci­sion. I also em­pha­sized two im­por­tant points: First was the chal­lenge and skill needed to get the air­craft into, and re­main in, the small win­dow just above the ground where the gear is above the turf but not too high where it will sink back down. One must get the air­plane into ground ef­fect as soon as pos­si­ble, but the slight­est set­tle back onto the mains will for­feit a sig­nif­i­cant amount of air­speed, re­sult­ing in the need for hun­dreds of feet of ad­di­tional run­way to re­cover the lost speed. This is much more chal­leng­ing than an­tic­i­pated when the only ex­pe­ri­ence a pi­lot has is from sim­u­la­tions on hard sur­faces where touch­ing the ground results in min­i­mal loss of air­speed.

The work­load, ac­cu­racy and fi­nesse re­quired to main­tain and ac­cel­er­ate in ground ef­fect is far beyond what is demon­strated and prac­ticed on a hard sur­face. The skill needed is anal­o­gous with and pos­si­bly more chal­leng­ing than learn­ing the land­ing round-out and flare.

Sec­ond was to al­low proper ac­cel­er­a­tion in ground ef­fect and not climb out of ground ef­fect un­til reach­ing Vx, or risk one of those de­par­ture stalls we all have prac­ticed up at al­ti­tude. A de­par­ture stall at low al­ti­tude will al­most cer­tainly re­sult in a bad end­ing, and in our case, im­pact with trees.

This was one of those times in a pi­lot’s life where what looks in­no­cent ends up be­ing very much the con­trary. Th­ese sit­u­a­tions can re­sult in in­valu­able ex­pe­ri­ence gained, but with­out proper knowl­edge go­ing into it, they of­ten end in ac­ci­dents.

Pi­lots who reg­u­larly fly in and out of turf fields usu­ally have on­go­ing re­cent knowl­edge about field con­di­tions and have a much bet­ter abil­ity to in­ter­pret run­way con­di­tions dur­ing a visual low pass. What I’ve learned, for those of us with lim­ited soft-field ex­pe­ri­ence, is that it’s wise to get a first­hand field re­port be­fore land­ing. Most public fields have a pub­lished phone num­ber read­ily avail­able.

I now re­al­ize that, be­cause this field was less than 2,000 feet long, af­ter land­ing and see­ing the run­way con­di­tion was soft and muddy, I should not have at­tempted the take­off. I would have been bet­ter off hear­ing my lessthan-thrilled boss’s voice when I ex­plained that we wouldn’t be able to safely de­part rather than my fam­ily get­ting the phone call had the de­par­ture ended badly. A bruised ego is so much bet­ter than a bruised body.

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