I was fortunate to get the following comments and observations
from Bruce Grayson, one of our Association members and an ex-CO of 3 Squadron
at Butterworth (March 1977-July 1979), so I present them without alteration:
“Aircraft accidents rarely result from a single causal factor
and this accident is no exception. There are several factors involved here;
any of which, if eliminated, could easily have influenced the result.
1. The pilots were on different radio frequencies - one on
tower frequency and the other on GCA (Ground Controlled Approach) frequency. This is a standard, normal, necessary procedure but does mean that one
cannot hear the instructions being given to the other.
2. The departing aircraft, because of the ground tests
required before takeoff, had entered the runway from the ORP (Operational
Readiness Platform) which placed him further down the runway than usual and
was positioned within the ‘normal Mirage touchdown zone’, i.e. 500 ft down
3. The ‘normal touchdown zone’ was contaminated with black
rubber deposits - the result of many years of aircraft landings. When
combined with the dark Mirage camouflage paint scheme, this made any Mirage
aircraft within this area very difficult to see from the air, especially by
the pilot of a Mirage which has a very high angle of attack at normal
approach speeds. Apparently, and as a result of this incident, a regular
program of de-rubbering the runway thresholds was introduced and continues
to this day.”
The official report from the Spotlight publication is shown
below and includes an aerial view of a Mirage parked on the ‘rubberised’
section of the runway. Camouflage painting of aircraft obviously works.
Whatever the reasons for this most tragic accident, it reminds
us of the inherently dangerous pastime of flying aircraft, more so when they
are in the high-performance category, as was the Mirage. Most aircraft
accidents can be tracked back along the ‘chain’ and in hindsight, it becomes
obvious that a (‘what if?’) link were to be broken, the accident may
well have been avoided. This can be as simple as a missing split pin, a
again’ to an indistinct radio transmission, or a feeling that something is not
quite right. I’m sure all of us have been in a situation where we have
thought….what if? Personally, I recall our Herc being given a line-up
clearance at Townsville one clear sunny day when a B737 was on short
finals… The silence from the tower when we said, “is that after the Boeing?”
was deafening. A good
lesson for all concerned.
I have added some other photos [movie stills] of the wreckage
of the aircraft involved which have come across my desk, courtesy of another
one of our members, Barry Roberts.
article appeared in the February 2014 Issue of
Aviation Safety Spotlight.
Reproduced with their kind permission.]
By Paul Cross. (Deputy
Director Safety Communications,
A Mirage at Butterworth in 'landing' attitude.
[This photograph dates from the era 1986-88, as it shows 79SQN markings.
79SQN took over 3SQN's Mirage
aircraft and a large majority of the Mirage personnel on 31 March 1986, as 3SQN was
due to re-establish in Australia, introducing F-18s to RAAF operations.]
About 2pm on 6 July 1976, Mirage A3-64
was landing from a practice
ground-control approach (GCA) and impacted Mirage aircraft A3-26 which was
lined-up on runway 18, waiting for take-off clearance.
A3-26 was destroyed and its pilot killed instantly. A3-64 was
also destroyed, but the pilot escaped without significant injury.
Both aircraft were engulfed in flames almost immediately after
impact. As the aircraft separated, A3-26 continued to burn fiercely as did
A3-64, with the exception of the partially-broken-away front fuselage
section. About three minutes after impact, the first crash vehicle arrived
at A3-64 and had no difficulty in rapidly extinguishing the fire. Simultaneously, other crash-rescue vehicles were directed to A3-26, where the
fire in the vicinity of the cockpit area was quickly controlled. However,
considerable difficulty was encountered in containing and extinguishing the
fuselage fire because of fuel leakage and numerous flashback fires.
The ambulance arrived after
about seven minutes and the duty medical officer declared the pilot
The pilot of A3-26 was a Category B fighter pilot with a total
of 1,187.4 hours, including 761.5 on Mirage and an authorised squadron test
pilot. The pilot of A3-64 was a Category C fighter pilot and considered most
dependable, conservative in his approach to flying and well aware of his
capabilities and limitations.
The impact scene.
Following the investigation, the Court of Inquiry
outlined several factors that were integral to the tragic events of 6 July:
Three days before the accident, the pilot of A3-64 had returned
from a 54-day holiday in Europe. He would have, in that time, established a
sleeping pattern consistent with the northern hemisphere summer and, having
travelled east to return to Butterworth, would have experienced a time-shift
of more than seven-and-a-half hours. His sleep pattern on return showed
evidence of significant disruption consistent with interference to the
normal circadian rhythm.
The Court noted, “One response to circadian dysrhythmia relates
to the tendency for mental blocking or lapses in attention. This phenomenon,
termed response blocking, has been under investigation in the analysis of
accidents, where subjects have apparently failed to see, interpret or react
to apparent or dangerous situations”.
Other Physiological Factors
Other physiological factors could also have influenced the
pilot’s performance level, including his loss of heat acclimatisation and
sleep deficit. It was accepted that there would have been a loss of acclimatisation after 54 days in a temperate climate and that it was very
unlikely that the pilot had re-acclimatised in the three days before the
“Two lengthy sorties and a
low fluid intake (one cup of black tea and a drink of water) would lead to a
body-fluid deficit. The effect of this deficit and loss of acclimatisation
would be to increase the individual’s susceptibility to the effects of heat
with the resultant fatigue.”
On the two nights before the accident, the pilot had only
slept a total of nine-and-a-half hours.
“Sleep deficiency will result in fatigue… fatigue produces a
further decrease in performance in an individual subjected to time zone
Following a lengthy break, the pilot of A3-64 was considered
“a little rusty” by his supervisor in a simulator refresher before flying. His flying of the GCA that culminated in the accident was flown very
accurately. It was thought that the attention to accuracy could impose a
“greater than usual” workload on top of an already medium-to-high workload
situation. “The pilot was in the habit of checking his glideslope and
centreline at the commencement of the approach then monitoring his approach
on TACAN, which he did. Because of his lack of currency he only monitored
the TACAN range but did not compare expected height with actual height or
monitor approach on the air-to-ground radar. That is; he was load shedding.”
GCA Four-Mile Call
The pilot of A3-64 at the four-mile point was given an
instruction by ATC to check wheels and to overshoot at minimas. This call
was given amid glideslope and heading information and was acknowledged by
the pilot. However, he did not obey the overshoot instruction and was
confident in his own mind that after GCA minimas he had been given clearance
“An important point in regard to the four-mile call is the
fact that there was no laid-down requirement to read back the key executive
word of such a clearance.”
“In this particular case, read back of the executive
‘overshoot’, firstly, would have confirmed with the controller that the
clearance had been heard and understood and, secondly would have reinforced
the executive in the pilot’s short term memory, enhancing retrieval or,
alternatively, reducing the probability of substitution.”
“The Court therefore believes that had overshoot been read
back, there is a high probability that the causation chain would have been
Hand-off at Minimas
The hand-off call given to
A3-64 by the controller was “continue visually and call the tower on the
go.” In contrast, the standard call, as contained in the manual was, “look
ahead and land/overshoot visually.”
The hand-off call was non-standard and importantly did not
contain the essential executive word overshoot. This was not a positive and
reinforcing four-mile call and contained the ambiguous phrase “on the go”.
Some pilots interviewed contended that ”on the go” was consistent with the
continuation of a touch-and-go but all, including the pilot of A3-64, stated
they would not interpret the phrase as a change of clearance but would
respond to the previous instruction to overshoot and at the least query
Departure and Arrival
It was accepted and common practice at Butterworth to line-up
aircraft with other aircraft on finals. Some controllers would not have done
this with an approaching Mirage within three miles of touchdown but at the
time of this accident no distances were laid down for visual meteorological
conditions (VMC) operations. In this particular instance controllers thought
the approaching aircraft was beyond four miles—when in fact it was about
Had A3-26 been positioned at the runway threshold, there was a
possibility that A3-64 might have cleared it, but A3-26 was some 500 feet
further along the runway — close to the touchdown point for a
ground-controlled approach. This would create a visual problem for the
A Failure to See
The pilot of A3-64 did not perceive A3-26 lining up 500 feet
from the threshold of runway 18 and there were a number of factors that
could account for this.
A camouflage-painted aircraft sitting on the rubber-darkened
section in the centre of the runway is not so easy to see. It has a very low
contrast ratio and added to this would be the hot gasses emitting from the
engine, reducing sharpness of the aircraft’s outline. A3-26 was stationary,
reducing the approaching pilot’s visual cues that he was on a collision
The position of the sun made it unlikely that any glint from
the Mirage’s canopy would be seen by the approaching aircraft.
“During a simulation it was apparent that the target aircraft
became invisible when displaced one to two degrees from the central vision. Thus, unless A3-26 had been fixated centrally, the probability of target
detection and recognition would have been very small.
“Although many pilots are unaware of reflections in aircraft
windscreens, this does not alter the fact that they impose an additional
load on the visual system and reduce contrast ratios of targets seen through
these reflections, thereby reducing the probability of successfully
detecting a low-contrast visual stimulus.”
Another factor is that the pilot of A3-64 did not expect to
see an aircraft lined-up on runway 18, if he thought he was cleared to land.
Further, he did not expect an aircraft to be lined up 500 feet from the
threshold, where A3-26 was located.
“These factors will affect both the pilot’s visual search
strategy and also the perception formed by the brain in response to a
particular visual stimuli. The probability of perceiving an aircraft on the
runway is likely to be less in these circumstances for a just perceptible
A3-26 represented a visual target with a low probability of
detection. The effects of fatigue and circadian dysrhythmia may have
aggravated the situation by raising visual thresholds, particularly in the
periphery, where high workload situations can lead to tunnelling of vision.
The Court concluded that while A3-26 was seeable, the
possibility of it being seen by the pilot of A3-64 was remote.
Approach view on finals at Butterworth with a camouflaged
Mirage holding in the rubberised area.
At the time of the accident, a trainee controller from the
RMAF was under supervision and working in the Tower 1 position. From the
time the pilot of A3-26 called “ready”, there was a delay of one minute
before he was given a line-up clearance. Although there was other traffic in
the pattern, there were opportunities to line up A3-26 and obtain a
departure clearance from approach.
After clearance from the approach controller was given, there
was further delay and discussion about the possibility of an airborne
confliction between A3-26 and A3-64 and the decision was made to await the
overshoot by A3-64 before clearing A3-26 for departure.
“As the controllers had witnessed previous low overshoots, it
was only three or four seconds before impact that they realised that A3-64
was continuing with the landing. At this point a controller called
‘overshoot’ into the microphone while another was attempting to select all
By this stage the accident was inevitable. While the delay in
clearance of A3-26 was a link in the causal chain, under the circumstances
no criticism of the controllers was intended or warranted.
The primary cause of the accident was that the pilot of A3-64
landed without clearance, but that landing was the effect of numerous causal
factors that coalesced into a series of events, any of which by themselves
would have been insignificant - but in this instance came together at one
place and at one time for tragic consequences. This complex chain of events
could have been broken at many points by the removal of just one of those
Deputy Director Safety Communications Comments:
The use of non-standard radio calls by both aircrew and ATC
continue to be contributory in some Defence aviation safety occurrences (PC9
near CFIT at Albury, April 2013; separation break-down between a foreign
military aircraft and a civilian light aircraft, March 2014) with luck often
playing a large part in averting disaster. If nonstandard radio calls are
detected, it behoves the receiver to question and clarify the call to ensure
that there is no miscommunication and both parties understand what is meant
This accident as usual had numerous contributing factors and
failed or absent defences that culminated in tragedy when the pilot
mistakenly landed without clearance. Could the accident causation chain have
been broken had the other aircraft back-tracked and lined-up at the
threshold rather than the usual practice of simply taxiing out of the ORP
and lining up, or if the upper surface of the Mirage been fitted with an
anti-collision light, or the pilot on approach realised and questioned the
non-standard radio call?
Physiological and psychological factors were also
contributory. Such factors can compromise the safety of a flight by
increasing susceptibility to errors and degrading decision making and flying
abilities. Pilots are encouraged to use the IMSAFE checklist which is
designed to help pilots check whether any of these factors individually, or
in combination, affect their physical and mental state before each flight.
each flight, ask yourself the following questions:
– Am I sick today? Am I coming down with a cold or other ailment?
– Am I taking any medications that would impair my ability to act as Pilot in
– Am I under a lot of stress right now (work, family, or other pressures)?
– Have eight hours, or more, elapsed since I last consumed alcohol?
– Have I had enough rest or am I feeling sleepy?
– Have I had enough to eat or am I feeling hungry or thirsty?