Jim Davis

This discussion is to promote safety and not to establish liability.

The CAA’s report contains padding and repetition, so in the interest of clarity, I have paraphrased extensively.

Name of Owner/Operator             Dr. T.R. Chamberlain

Aircraft registration:                       ZS-DVF

Date and time of accident:            16 December 2003; 0515Z

Type of aircraft:                             PIPER PA 22-108 

Type of operation:                          Private

PIC license type:                             PPL

License valid:                                   Yes

PIC age:                                            81

PIC total hours:                               4065.2

PIC hours on type                            49.2

Last point of departure:                 Krugersdorp Aerodrome (FAKR)

Point of intended landing:             Krugersdorp Aerodrome (FAKR)

Location of accident site:               Moedhou Farm, Hartebeesfontein

Meteorological information:         020°/10 knots; 20°C; Viz >10km

POB:                                                 1 + 1

People injured:                               0

People killed:                                  1 + 1

History of flight:

The aircraft departed from Krugersdorp on a private flight on the morning of 16 December 2003.

It was observed flying in the Hartebeesfontein area at about 0510Z. The eyewitness said it was at about 300’ AGL and was circling over a particular area.

The wind was from the northeast. Prior to impact, the aircraft was flying downwind and then turned south, flying straight and level towards the witness. The engine was operating at a constant speed. The aircraft then turned left, into the wind. The first 90° of the turn seemed normal, followed by a sudden increase in the bank and it dived into the ground.

The pilot was in radio contact with a person on the ground who had a private landing strip on her property, close to where the accident occurred. They were having a casual conversation on 125.8 MHz approximately 10 minutes prior to the accident, as the pilot flew over her property.

The aircraft impacted terrain in a substantial nose-down attitude on a heading of 326°M. No post impact movement was evident on the ground. The forward fuselage section, including the cockpit area and both wings were severely damaged.

Medical Information:

The pilot held a valid Class II aviation medical. No alcohol was found in his blood. According to the post-mortem report both occupants’ cause of death was multiple blunt force injuries.

Analysis

The aircraft was properly maintained and no defect or malfunction that could have contributed or have caused the accident was found.

The pilot had been flying for many years and was appropriately rated. There was no indication that incapacitation or physiological factors had affected his performance.

According to the eyewitness the pilot executed several low-level orbits in the area without any problem. The turn prior to impact was initially uneventful, but then the bank angle increased suddenly and the aircraft dived to the ground.

Probable Cause

It is the opinion of the writer that the aircraft stalled with insufficient height to recover.

Jim’s comments:

This is a very interesting accident for a few reasons. First, the FAA has an exercise in the PPL syllabus, designed specifically to avoid this sort of accident. It’s called ‘Turning Around a Point’ and it’s part of a family of exercises called ‘Ground Reference Manoeuvres’.

The object of these exercises is to teach you to manoeuvre safely, at low level, in wind, with reference to objects in the surface.

You may think, well I don’t really do that. But you actually do it every time you turn on to final approach. The point on the ground is the runway threshold. If you have a tailwind on base you are likely to overshoot the centreline, in what’s known as a hammerhead. This is dangerous because you have to tighten this low level, low speed turn to the extent that you could stall.

Two people have just died in a Lancair Super ES on the opening day of the Oshkosh airshow on Monday, July 22. The initial evidence points to them stalling during a hammerhead on their base to final turn.

Other ground reference turns are when circling to photograph a building or a herd of animals or a beauty spot. Pilots involved in game capture, advertising or tourism are prone to run into trouble – particularly if there’s a strong wind.

The worst day we ever had at 43 Air School was two weeks after an Italian couple left their beautiful young daughter with us for PPL training. The father’s final words to Steve Goodrick, our CFI, were “Please look after my little girl.” I was on holiday in Zim.

Fourteen days later Steve had to phone daddy in Italy to tell him that his daughter was dead.

She and her instructor had crashed into the sea in front of scores of holiday makers who were watching a whale.

A month later the aircraft was found when a fishing trawler snagged it. The instructor’s body was recovered but the Italian girl was never seen again.

Her parents came out and built a memorial above the beach overlooking the spot where their daughter had disappeared beneath the waves.

CAA’s investigation was inconclusive, despite there being many witnesses. It seemed that the aircraft had spiralled down from three or four thousand feet where they had been doing upper air work. It then started circling the whale at low level and suddenly pitched down into the sea.

I spoke to a number of people who had seen the accident – one in particular demonstrated the futility of interviewing eye-witnesses. He said the aeroplane was flying along the beach and he knew it was going to crash because one of its engines was stopped. The aircraft was a 180 Cherokee.

The instructor had fallen into the trap of circling round an object in a strong wind. It was about 25 knots that day.

The danger is that you run out of airspeed on the downwind side of the turn because the high groundspeed deceives you into thinking you have plenty of flying speed.

The exercise “Turning Around a Point” is in the FAA syllabus, however it not part of the South African PPL or CPL training. It’s partially covered under “Low Flying” during which we teach the pupil to rely on airspeed and ball, and ignore groundspeed and apparent skid and slip while flying a racecourse pattern.

Australia only teaches low flying as part of a separate rating – it’s not in the basic license.

Here’s what should happen:

Turns Around a Point

The object is to do a 360° constant radius turn around a surface-based point. The faster your groundspeed the steeper you need to bank, and slower your groundspeed the shallower your bank angle.

You need to:

  • Maintain a relationship between the airplane and the ground.
  • Divide your attention between the flightpath and the reference point while flying accurately and checking for outside hazards and instrument indications.
  • Adjust bank to correct for groundspeed changes. You need a steeper bank as groundspeed increases and a shallower one for decreasing groundspeeds.
  • Establish the wind correction angle and adjust it to maintain your track over the ground.
  • Develop an awareness of the relationship between turn radius and bank angle.

When you try it, your first 360° will let you assess what’s happening. Subsequent turns will improve as you learn to continually adjust the bank with coordinated aileron and rudder.

You should enter the manoeuvre downwind, where the groundspeed is at its fastest.  In a high-wing aircraft, the wing may block your view of the point. To prevent this you may need to change the altitude or turn radius.

When you enter the manoeuvre, depending on the wind speed, you may need to bank rapidly so that the steepest bank is established quickly to prevent drifting outside your planned radius. It takes a bit of practice to get this right.

Then you need to gradually decrease bank until you are heading directly into wind. Next, as your turn becomes a crosswind, and then downwind, you have to gradually steepen the bank until the steepest bit is at your initial entry point.

Common faults

  • Relying on perceptions instead of airspeed and ball.
  • Not clearing the area for safety hazards.
  • Not establishing straight and level before starting.
  • Not maintaining altitude during the turn.
  • Not properly assessing the wind direction and speed.
  • Not using the controls smoothly and continuously.
  • Not coordinating aileron and rudder, causing slips or skids.

Note: If your bank exceeds 45° you are too close to your point.

If you get all this right you might even earn a pat on your back from that ogre who poses as your instructor.

I have to admit that I almost killed myself when I had about five hours of solo in a J3 Cub. Dirty Bossie, my instructor, sent me off to practice stalls or something. I used the opportunity to circle over our home where my beautiful young wife was waving a dishcloth from the lawn.

The wind was howling and of course I stalled after throttling back while on the downwind part, while pulling the turn too tight.

The gentle yellow aeroplane forgave me when I didn’t deserve it.

Take home stuff:

  • Don’t go low flying
  • Really, really really don’t go low flying in a wind.