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The Soft Field Procedure

Before I learned precautionary and forced approaches, I learned about soft field landings.  Here my account of the experience, and why soft fields are important and should be practiced regularly.

When will we use a soft field landing?

If we are planning to land on an unprepared surface. We also need to know the technique if we need to make a precautionary or forced landing, and have to put our airplane down in a field.

Like the short field procedure, the soft field is a lot of fun.  It is used when taking off and/or landing on an unprepared surface. The can be a grass strip or turf runway, or a completely unprepared runway.  One of the main goals is to protect your propeller and engine in the sequence. This means we try to keep it from being struck by flying debris and damaged, and to keep dirt and debris from being sucked into the engine.   It also is to keep the nose gear from diving into a hole – since it is an unprepared surface there may be lots of surface irregularities.  A small dip and we could wheelbarrow the plane.  We keep the nose high throughout the procedure as long as we can.

It starts during the taxi

Can I land my airplane in that field?
Can I land my airplane in that field, and what is the technique?

In fact, when we taxi on the unprepared runway we keep our control column full aft.  So when we pull up to line up on our runway we are pulling back as far as we can on the control column.  When we add power, we push forward slightly on the column until the airplane is ready to fly.  We rotate at about 46 knots with 10 degrees of flap in the 172 N model.

We fly in ground effect until we have built up enough airspeed to climb.  This is about 60 knots, so when we reach 60 knots, we pull up and climb out.  At 200′ AGL we announce that we have “two positive rates”

(1) altimeter increasing (showing a gain in altitude), and

2) vertical speed indicator increasing, and we retract the flaps and climb out normally at 70 knots.

Hold off on the landing

The airplanes POH will show us what speed to approach for our soft field landing.  In the 172, we use 61 knots.  The idea on the flare is try to hold off landing even longer than usual to keep the airplane nose high.  So after we flare and we feel the first “sink”, we add a bit of power, around 100 RPM or so and try to keep the airplane from touching down. We do so until we have run out of altitude, and the airplane will touch down very softly.  We keep the nose high to protect the propeller and keep from nose gear from running into rough terrain.

Soft field touch and go’s are probably the most fun of all – we do not push the nose down, and take off right away in a nose high attitude.  That means we stay off the nose wheel and just do a “wheelie” down the runway, and take off! In my solo I managed to make this happen a few times.

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Precautionary Landings

Starting Point for Precautionary Landing. Image Courtesy of Langley Flying School.

Preparing for a precautionary landing

My next series of flights gets me out of the circuit and back into the practice area where I am learning how to do a precautionary landing.

Why do we need to learn this?

There are a number of reasons.  You may have a sick passenger on board, the weather may be a cause of concern.   There may be something that you are concerned with, such as an engine that is acting up, you may be getting low on fuel and think you may not make it much further. In any case, the landing is done to avoid a potentially worsening situation and is done so while engine power is available.  The sooner the landing area is selected the better once a precautionary landing has been decided.  Quite simply, a precautionary landing is completed in two basic steps:

1)  A low pass flown like a circuit over the potential landing area, this is done to inspect the surface for suitability, and

2) A normal circuit flown to end in a safe landing.

There are two basic procedures, one for a controlled airport and one for an uncontrolled airport. In the case where a field is selected, this is obviously uncontrolled.  This is what I have been practicing on.  When we arrive at the practice area, which is the Cremona area just north of Springbank,  we broadcast our intentions for the exercise then proceed to look for a field we can “land” on.

Starting Point for Precautionary Landing. Image Courtesy of Langley Flying School.
Starting Point for Precautionary Landing. Image Courtesy of Langley Flying School.

We find a field and enter a normal circuit approach. The goal is to make two passes: a high pass and a low pass to judge the suitability of the field for landing.

In an uncontrolled field, such as a farmer’s field, we make a high pass at 1000′ AGL and in a controlled field like an aerodrome we do this at 1500′.   Our high pass is done at cruise settings, 90 knots in the 172.  We fly the normal circuit at 1000′ and then overshoot.

Then we do the “3 Ps“:

(1) Pan Pan call: alert traffic in the area that we are preparing for a precautionary landing.  We say “Pan Pan” three times and say our aircraft identifier (for example, FIAH, GSKF, and so on) three times.

(2) Passenger brief. Let your passengers know what you will be doing, to stay calm, to put their hands free of the controls, and to move their seat back (if sitting in the front).  Then:

(3) We do our Pre-landing checks.

Then we do the low pass. This is done 500′ AGL or whatever altitude is best for inspecting the landing area. In the 172, we fly at 60 knots with 20 degree flap.   The slower speed will allow for better inspection of the field, and the flaps will allow for better forward visibility. The speed is also not too slow – that is it’s not in the slow flight range – which will allow the pilot to focus on observing the field rather than maneuvering the airplane. We also want to prevent getting close to a stall.

Precautionary Landing Procedure. Image Courtesy of
Precautionary Landing Procedure. Image Courtesy of

On our observation of the field, we want to do our “COWLS” check, for suitability in landing:

C = Civilization: are there homes, buildings, or people nearby?

O = Obstacles: are there any obstacles that need to be cleared, such as powerlines, or trees?

W = Wind: always try to land into the wind if possible. Look for indicators on the ground: direction of smoke, direction of long grass, trees, etc.  Is smoke trailing upwards (calm winds), being blown slightly (gentle winds) or rapidly breaking off (strong winds)?

L = Length: once we are abeam the threshold, we count how many seconds it takes us to fly the length of the field. This is why we use 60 knots at 20 degree flap in the 172: if we count the seconds it takes to fly that length, we can estimate the approximate length of the field.

On the low pass, 500′ AGL, abeam the threshold, we start the timer. If it’s 20 seconds, the length is 2000′, (20 * 100); if it takes 33 seconds, the length is 3300′, (33 * 100)  and so on.

S = Surface: Check the suitability of the surface for landing. For example, are there ruts in the ground, or is the surface smooth? Is the surface grass or dirt?

Once our high and low passes are completed, we establish for a normal approach with full flaps.

Next read about the forced approach and see where it actually happened in real life!