accident report
TRANSCRIPT
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Accident report
Synopsis
This is an accident happened at 1609 hours on 20 May 1988 at The Coolangatta
Control Tower’s control area. Two aircraft collided each other and all of the crew was
killed. When the accident happened, Piper PA38-112 VH-MHQ was doing its circuit
and preparing for a touch-and-go, and Cessna 172-N VH-HIZ was just finish a touch-
and-go and making an early right turn after takeoff. The day of the accident was a
normal Friday but the Coolangatta Control Tower suddenly became busy 10 minutes
before the accident. There were 12 aircraft came into the Coolangatta Control Tower’s
area which made the traffic controller became busy suddenly.
1.0 Factual information
The Cessna 172 VH-HIZ was an aircraft for training pilots, and the flight was
used for training a pilot who had never flown since 1982 and had 10 hours flight
experience on Cessna 172 aircraft. The aircraft took off at 1529 hours and had
completed five touch-and-go landings before the accident. The other aircraft, Piper
PA38 VH-MHQ was also a training aircraft, but operated by another training
organization. The particular flight was training another pilot, who had not flown
for some years and only had 2 hours experience for flying PA38 aircraft. VH-MHQ
took off at 1558 hours and had completed one touch-and-go landing before the
accident. Both of the two aircraft were within the specified limits and had enough
fuel for complete their flight mission. In addition, both of these two aircraft did not
have any maintenance problems. When the accident happened, VH-HIZ was
applying for the sixth touch-and-go landings and VH-MHQ was doing its second
circuit on downwind. All of the crew of these two aircraft was killed by this
accident.
The Coolangatta Control Tower had three controllers on duty at that day. This
is a normal staffing level foe a Friday afternoon/evening shift. All of these three
controllers have more than 10 years’ experience for the traffic controlling and they
had clearly defined responsibilities. However, the Surface Movement Control had
temporarily do the job for the Coordination from 10 minutes before the accident.
The view of the sky was clear, but some pilots responded that they do not had a
clear sight because of a lack of definition and contrast. This situation was most
noticeable cause by the thunderstorms in the west of Brisbane. Thus, the difficulty
sight would happened when looking towards north-west. On the other hand, there
was no evidence advised there was some misunderstandings between the
Coolangatta tower and pilots.
The medical reports point out that there was no medical aspects that may cause
or affect this accident. In addition, there was no evidence was found which could
supports that this accident was caused by some psychological factors. Furthermore,
neither of these two aircraft had flight recorders to memorize the flight attitude
during the accident time.
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According to the transcript of recorded communications, it can be seen that
from 1556.15 hours, the Coolangatta tower became busier and busier. At 1555.52
hours, the Aerodrome control (ADC) spend quit a long time talking with the
aircraft VH-FNO because they have some misunderstandings between each other.
The pilot of VH-FNO was confused about what the right steps they should do next.
At 1602.59 hours, VH-MHQ was cleared for touch-and-go and turned to the right
side when it took off again. However, the controller did not stipulate the high level
that VH-MHQ need to reach or ask the high level of VH-MHQ until the accident
happened. In addition, the controller had never said anything with VH-MHQ from
1602.57 to 1607.47 hours. On the other hand, the controller had told VH-KZG
twice to descent to three thousand, but VH-KZG seems had not got the message
and asked the third time. At 1606.01 hours, the controller told VH-HIZ to keep
speed up when it was circuiting. At 1607.13 hours, the controller told the VH-HIZ
to do its last touch-and-go before the accident happened and asked VH-HIZ to
make an early right turn after takeoff. A short time later, at 1607.52, the controller
told another aircraft, VH-FNO, to do its touch-and-go and turn left after takeoff.
At 1608.01 hours, the controller asked VH-SON whether they could see the VH-
MHQ which they should see if the air was clear. Until 1608.43 hours, the controller
asked VH-SON twice whether they could see VH-MHQ, but they still could not
see it, and at that time, the VH-MHQ should be flying at the north-west of VH-
SON. Because VH-SON still cannot see VH-MHQ, the controller asked CH-SON
whether they were at one thousand five hundred at that time, and the controller got
the affirmative answer.
2.0 Analysis
All of the traffic controllers of the Coolangatta Control Tower had more than
ten years’ experience. Therefore, the busy traffic at that day was not an overload
for them because they must had meet this situation many times before. However,
from the transcript of recorded communications, it can be seen that the traffic
controllers still had some negative actions. Firstly, the controller spend a long time
discussing with VH-FNO about what they want and need to do around 1556 hours,
which made both of the traffic controller and the pilots of VH-FNO confused. The
transcript of recorded communications shows that the Coolangatta Control Tower
was already became busier from 1556 hours, thus this long time communication
waste a long time. This situation may cause the traffic busier because there would
have more aircraft arrive this area as time went on. Secondly, during the whole
communications, the traffic controller had never asked VH-MHQ about their high
level and had never gave any instruct to VH-MHQ about what high level they need
to keep after they finish touch-and-go and took off again. That means the traffic
controller did not know the high level of VH-MHQ from the start of the
communication to the accident time. In addition, the traffic controller ask VH-SON
whether they can see VH-MHQ and whether they are at one thousand five hundred
at 1608 hours, but the controllers did not notice that he had not asked or instructed
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VH-MHQ about their high level. Thirdly, the traffic controller told VH-KZG to
descent their high level three times, but the controller did not get any feedback that
VH-KZG had received the order at first two times. However, the controller did not
asked whether VH-KZG could hear what he said and whether they had received
the order, until the third times. During that time, VH-KZG had flied 3 miles without
any decrease of high level. This may cause VH-KZG force on entrance into other
aircraft’s circuit. Thirdly, the traffic controllers did not notice that there were two
aircraft displayed on the screen were closing to each other until the accident
happened. At the same time, there must also had any warning massage shown on
the screen which may because the Coolangatta Control Tower did not have the
equipment to measure the high level of the aircraft. The controller could only know
that these two aircraft were going to cross each other, but did not know they are in
the same high level. Finally, the traffic controller made two aircrafts to close. At
1606.01 hours, the controller told VH-HIZ to keep their speed up. This may
because the aircraft VH-FNO which was behind VH-HIZ was too close to VH-HIZ.
Because this two aircraft were too close and both want to make a touch-and-go, the
traffic controller ask VH-HIZ to make an early right turn after it took off which
made VH-FNO have enough space to take off after a short time but did not worry
about force on entrance into VH-HIZ’s sinuous flow. This plan is a good way to
relieve the load of the airport when it is too busy, because this plan make the
runway more effectively. However, this plan made VH-HIZ turned too early and
fly into VH-MHQ’s circuit, and finally collided with VH-MHQ.
On the other hand, there was a thunderstorm at the north-west of this area.
This thunderstorm may cause the pilots did not have a clear sight when looking
towards north-west. From the transcript of recorded communications, it can be seen
that VH-SON cannot see VH-MHQ which was on their north-west at 1608 hours.
This was because of the thunderstorm and the pilots of VH-SON did not have a
good sight when looking towards north-west. However, the pilots of VH-SON
cannot see VH-MHQ may cause by another reason. That is VH-MHQ was not at
the same level at that moment. As this report analyzed before, the controller had
not asked VH-MHQ about their high level, thus VH-MHQ may not at one thousand
five hundred at that moment and VH-SON cannot see it obviously. If the unclear
sight towards north-west is true, this can be another reason for this collision. When
VH-HIZ collided VH-MHQ, VH-MHQ was at a higher level. Thus, the pilots can
hardly saw the aircraft coming to them from the down side. On the other hand,
when the accident happened, VH-MHQ was on the north-west of VH-HIZ.
Therefore, VH-HIZ can also hardly saw VH-MHQ because of the unclear sight.
From the factual information, it can be seen that neither of these two aircrafts
had flight recorders. This lead to the investigation harder to evolve. Without flight
recorders, it cannot be known what the pilots were talking in the aircrafts, whether
there were some events that affect the pilots’ attention and whether the pilots of
these two aircrafts had made some mistakes. At the same time, these two aircrafts
must not had collision-avoidance system to warn the pilot that they are closing to
another aircraft.
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3.0 Conclusions
Based on the factual information and analysis, this accident was caused by not
only one reason. Firstly, the traffic controller of the Coolangatta Control Tower did
not pay enough attention on the feedbacks given from each aircraft and did not care
about the high level of each aircraft. Secondly, the Coolangatta Control Tower and
these two aircrafts did not have enough equipment to make the flight safely enough.
Thirdly, the pilots of these two aircraft did not have a clear sight to see each other
when they were getting closer. Fourthly, the traffic controller instructed VH-HIZ
to make an early turning to clear the runway for VH-FNO which lead to VH-HIZ
invaded into VH-MHQ’s circuit. Finally, VH-MHQ’s circuit was too close to the
runway which made VH-HIZ collided it just after VH-HIZ took off.
4.0 Safety recommendations
upgrade the equipment of the control tower
The Coolangatta Control Tower need to add equipment for measure the high
level of the aircraft and the flight azimuth in its area and display the high level
data on the traffic controllers’ screen. This data could help the traffic
controllers make sure that every aircraft are in the right level and could clear
see that whether there are some aircrafts are in danger. With the high level data,
the traffic controllers could make sure that there are no close aircrafts are in
the same level. At the same time, the traffic controllers could also make sure
that the aircrafts have got their instruction and fly to the level that the traffic
controllers instructed. Furthermore, the screen showing aircrafts need to use
different colors to sign the aircraft which are too close or getting closer to each
other. This could also help the traffic controllers find out the warnings even
they are too busy. On the other hand, the flight azimuth system could help the
traffic controllers realize where each aircraft are going. It can also help the
traffic controllers estimate that whether the aircrafts are getting closer or
leaving each other. In addition, with the flight azimuth system, the traffic
controllers could intuitively to see where the aircrafts will go and find out the
aircrafts may collide some minutes later. This upgrade equipment could help
the traffic controllers realize the aircraft under-control more detailed and will
improve the safety of the aviation industry by decrease the collisions happen.
Training traffic controllers and pilots
Giving the traffic controllers trainings to make them keep in mind that they
need to pay attention to the feedbacks given by the pilots, and always focus
the aircraft’s high level and the aircrafts which are close to each other. The
feedbacks given by the pilots are quite important. The traffic controllers could
realize whether the pilots heard clearly and whether they have got the
instruction. The traffic controllers need to make sure that they get the feedback
from the pilots and must ask the pilots, whether they received the instruction,
if they did not get the feedbacks. Furthermore, the traffic controllers need to
pay attention on reading the high levels of each aircraft to make sure that every
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aircraft are in the right and safe level. In addition, the traffic controllers need
to develop a habit that always focus on the aircrafts which are very close and
double check that they would not collide. On the other hand, the pilots also
need to training for the communication with the traffic controllers. The pilots
need form a habit that always repeat what the traffic controllers instruct them
to do instead of only feedback with the flight number and ‘Roger’. Repeating
the instruction could help the pilots make sure that they have heard clearly and
got the whole instructions. With this trainings, the aircraft traffic
communications could become more formal and will cause less
misunderstanding or miss massage.
Add collision-avoidance system to the aircraft
The traffic control by the control tower is not always timely if the accident
happens so quickly. Therefore, the aircrafts also need to install collision-
avoidance system which could scan the area near the aircrafts’ selves and find
out other nearly aircraft. When the system find there is another aircraft near it,
the system of these two aircraft will transfer information to each other to make
sure whether they will collision under the current airway. If the system find
out there will accrue a collision, each aircraft will send warning massages to
the pilots and guide them to avoid each other, such as one aircraft climb out,
another aircraft descend, or one aircraft increase speed, another aircraft reduce
the speed. This collision-avoidance system could give the warning massage
swiftly and real-timely even the aircrafts are flying in an area whose control
tower do not have measure high level system. In addition, this system could
also be treated as a Double protection for aircrafts collision. Even one of the
collision-avoidance system and control tower fail to warning the pilots or
traffic controllers, another system could find out the dangerous.
Add flight recorder system to the aircraft
The flight recorders system is quite important for aircrafts. The most important
advantage for using this system is that it could make the investigation much
easier when an accident happens. The investigators could analyse the flight
data and find out the real time of the accident. At the same time, investigators
could also simulate the flight attitude through the flight data to find out what
the aircraft did during the accident. In addition, investigators could listen to
the flight recorder to realize what the pilots were talking about during the
accident. All of these information will help investigators find out the real
reason for the accident quickly, accurately and exhaustively. On the other hand,
the flight recorder system could also be used without an accident. The
designers and manufactures could find out the physical and electrical problem
and disadvantages easily through the flight recorder. And then, they could do
research to work out ways to improve the safety of the aircrafts. Furthermore,
the pilots training organizations could also use the flight recorder to find out
the mistakes of student-pilots both comes from operation and the
communication with the control tower. Then, the pilot training organization
could make education plan about what training they need to focus on.
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Therefore, the flight recorder system could increase the safety of the aviation
industry observably.
Stipulate the aircraft’s circuit area near the runway
This accident happened because an aircraft intruded into another aircraft’s
circuit when taking off. If the circuit of the VH-MHQ could be set a little
further, this accident would possibly not happen. Therefore, in case this kind
of accident happen again, the aircraft’s circuit area must be stipulated and the
area must far enough to the airports’ runways. As it all know that the area near
the airports are the busiest area when there are many aircrafts need to use the
only one runway of the airport. Therefore, the circuit area need to be set a little
further to the airport to make sure the aircraft would not intrude the cruising
aircrafts’ circuits. However, most cruising aircrafts are preparing for landing
and do not have much fuel. Thus, setting the circuit area much further may
lead to the aircrafts do not have enough fuel to reach the runway after a long
waiting. In order to avoid the aircrafts are lack of fuel, the aircrafts will carry
more fuel and the cost will increase. Thus, the circuit area cannot be set too far.
On the other hand, another way to solve this intrusion problem is increase the
high level of the circuit. The aircrafts which is just taking off cannot reach a
high level, thus set the circuit level a little higher could also avoid the
intrusions’ happen. In conclusion, set the circuit area further and higher to the
runway could make the aircrafts which are just raking off cannot collide with
the circuiting aircraft.
5.0 Bibliography
Australia transport and communications. Mid-Air Collision Between Cessna 172-N VH-HIZ and Piper
PA38-112 VH-MHQ Near Tweed Heads, New South Wales. accident inveatigation report,
Australia transport and communications, 1988.