accident report

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.

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

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.

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

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.

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.