THE DREADED HAMMERHEAD AGAIN.
This discussion is to promote safety and not to establish liability.
CAA’s report contains padding and repetition, so in the interest of clarity, I have paraphrased extensively.
Aircraft registration: ZU-YUM
Date and time of accident: 14 February 2015 1345Z
Type of aircraft: Lancair 360
Type of operation: Private (Part 91)
PIC license type: PPL
License valid: Yes
PIC age: 38
PIC total hours: 810
PIC hours on type 367
Last point of departure: Parys (FAPY), Parys, Free State
Next point of intended landing: Kitty Hawk (FAKT), Pretoria
Accident site: Next to Parys Aerodrome at 4728ft AMSL
Meteorological information: 31ºC; 270º/08 gusts 20-25; Viz 10k
Cloud Cover: None
POB: 1+1
People injured: 0
People killed: 2
Synopsis:
History of the Flight
On 14 February 2015, the pilot and his six-year old son took off from Kitty Hawk on a flight to Parys. They arrived at Parys at about 1030Z. They parked the aircraft and had lunch at the aerodrome’s restaurant.
At about 1330Z, they took off on Runway 24 for the flight back to Kitty Hawk. The pilot called the aerodrome’s safety officer on 123.5 Hz for a radio check. He said he was going to do a low fly-past over Runway 24.
The airspace is class G with unmanned procedures in force. The normal circuit for Runway 24 is a left-hand pattern but the pilot turned out right after take-off.
He flew over the town of Parys, and then over the airfield at low altitude and high speed from west to east. Witnesses estimated his speed to be about 170 knots.
One witness described conditions as ‘very turbulent’ with the wind gusting 20 to 25 knots.
After the aircraft flew over the witness it started a climbing turn to the left to position for a low level fly-past along Runway 24. It pitched up into a steep left turn, whereafter it nosedived into the ground.
The Lancair 360 is a kit-built, two-seater, low-wing, retractable, tricycle, monoplane constructed mainly of composite materials. It has a 180HP Lycoming engine and a fixed pitch propellor.
Basic Empty Mass | 1252 lbs |
Pilot | 212 lbs |
Passenger | 35 lbs |
Fuel | 162 lbs |
Cargo | 15 lbs |
Total Weight | 1676 lbs |
Maximum Take-off & Landing Weight | 1685 lbs |
Below Maximum Take-off Weight | 9 lbs |
The aircraft impacted the ground and then a wire fence. The propeller carved into the hard ground 11 m from the first impact. The engine was operating at a high power setting. The fibreglass wings disintegrated on impact and the engine was found 219 metres from the initial point of impact with no evidence that it had rolled along the ground. It appears to have bounced and travelled through the air for most of that distance, which indicates the high speed of the aircraft.
On 9 March 2010, the FAA published the following information circular for Lancair operators. (I have edited this for brevity.)
Accident statistics for the Lancair, have shown a large and disproportionate number of fatal accidents for the fleet size.
The majority being due to inadvertent stall/spins, while at slower airspeeds in home airport traffic patterns.
The FAA recommends that pilots:
- Review all information regarding the slow-flight and stall characteristics of their own Lancair.
- Obtain specialised training from a Lancair recommended instructor.
- Install an angle-of-attack indicator and/or a stall warning indicator (Note: indicated airspeeds can be as much as 10-20% off if not properly calibrated.)
- Have their aircraft’s rigging and mass and balance evaluated by a mechanic.
- Have their aircraft’s handling characteristics evaluated by a test pilot.
Probable Causes
The pilot lost control during a tight left downwind turn [sic] at low altitude, from which he was unable to recover.
The pilot had severe coronary artery disease with Gr IV occlusion of the left main artery. A heart attack cannot be excluded.
Jim’s comments:
Dear parishioners, much as I would like to deliver yet another sermon on downwind turns, it would not be appropriate – the CAA are talking through their underpants when they cite this as the Probable Cause. Hell, the aircraft was actually turning into the wind.
This crash was about hammerheads and twitchy aeroplanes. Let me explain both.
A hammerhead is when you overshoot the centreline on your base to final turn. It’s dangerous because you are low and slow. You start pulling back to tighten the turn. You know it’s not good to be banked steeply near the ground, so to tighten the turn you use more rudder.
But wait a minute, the secondary effect of rudder is roll. This means she will try to bank even more steeply, so you hold off bank with the aileron.
Sound familiar? Correct – you are all set up to spin in.
But I hear one of our parishioners, Captain Tailpipe, asking if it’s so bloody dangerous, why don’t these accidents happen all the time.
Ah-ha – a very good question Comrade. The short answer is we fly pansy aeroplanes like the small Cessnas and the Easy-Peasy Cherokeesy.
These little aeroplanes have thick wings like mattresses, which have gentle stall characteristics. They give plenty of lift at low speed but the wings are too thick and draggy to be fast.
If you want more speed then look at the wing on a Comanche, a Mooney or a 210, and you will see it’s much thinner, it causes less drag and gives you more speed at the expense of slightly twitchy low speed handling.
Now look at the wing on a Lancair – it’s like a razor blade – and it says clearly, don’t mess with me – I’ll cut you up before you can blink. It’s fast and twitchy as hell.
So wings are always a compromise between speed and gentle handling – you can’t have both.
In a fast, twitchy aeroplane like the Lancair, a stall is where it behaves badly. It will stall abruptly, with little or no warning, and will almost certainly drop a wing quite violently. As long as you have plenty of height this may be a bit alarming initially, but is not dangerous per se. You simply ease the stick forward and use opposite rudder to pick up a dropped wing.
The problem is that this seldom happens at altitude – it’s typically around the circuit.
And there are two common piloting faults that tend to make it dangerous. The first is being too slow with the recovery, which may lead to the aircraft becoming inverted as it enters a spin. And the second is trying to recover from the dive too soon, or two quickly, which can cause a secondary stall and possible spin.
So you need an immediate response at the first sign of a stall/spin, followed by a very gentle recovery from the dive.
Obviously plenty of altitude is the secret – however it’s generally not available if you are trying to impress your mates on the ground.
Did you notice that the FAA’s special bulletin to Lancair pilots stated that most of these fatal stall/spin accidents happen at the pilots’ home fields? I was much puzzled by this initially but some research turned up at least three possible reasons.
- Pilots tend to be more relaxed and generally more slack at their home fields. The only time I came close to a wheels-up landing was at my home field.
- Pilots are inclined to, either consciously, or subconsciously, use landmarks around their home circuits. And while these landmarks are fine for say 100 kts around the pattern, they are far too tight for a show-off 170 kts beat-up. So you are heading for a hammerhead unless you allow for this and are wide awake.
- I guess it’s just stats because you do most of your flying at your home field.
All aircraft tend to roll away from the ball, regardless of the direction of the turn. So if the ball is to the left she will roll, or even flick, to the right, and vice-versa.
However this is of academic interest only if you are yanking the turn too tight while looking over your shoulder to see if you can line up with the runway.
I’m afraid this was a classic case of PPP – passive people pressures. Would he have done that if the airfield was deserted and he had no pax? I think not.
Take home stuff:
- Am I doing this flight or manoeuvre to please or impress other people?
- If you have a twitchy aeroplane don’t be scared to stall it. Grab a good instructor, go up high and stall the hell out of it in all configurations and attitudes until you understand its low speed handling.
- Be particularly vigilant at your home field.