On 15 May 2003, at about 0833 Eastern Standard Time (EST), a
Raytheon1 Beech Super King Air
B200C, VH-AMR, impacted the sea or a reef about 6 km north-east of
Coffs Harbour airport. The impact occurred immediately after the
pilot initiated a go-around during an instrument approach to runway
21 in Instrument Meteorological Conditions (IMC) that included
heavy rain and restricted visibility. Although the aircraft
sustained structural damage and the left main gear detached, the
aircraft remained airborne.
During the initial go-around climb, the aircraft narrowly missed
a breakwater and adjacent restaurant at the Coffs Harbour boat
harbour. Shortly after, the pilot noticed that the primary attitude
indicator had failed, requiring him to refer to the standby
instrument to recover from an inadvertent turn. The pilot
positioned the aircraft over the sea and held for about 30 minutes
before returning to Coffs Harbour and landing the damaged aircraft
on runway 21. There were no injuries or any other damage to
property and/or the environment because of the accident.
The aircraft was on a routine aeromedical flight from Sydney to
Coffs Harbour with the pilot, two flight nurses, and a stretcher
patient on board. The flight was conducted under instrument flight
rules (IFR) in predominantly instrument meteorological conditions
(IMC).
During the descent, the enroute air traffic controller advised
the pilot to expect the runway 21 Global Positioning System (GPS)
non-precision approach (NPA). The pilot reported that he reviewed
the approach diagram and planned a 3-degree descent profile. He
noted the appropriate altitudes, including the correct minimum
descent altitude (MDA) of 580 ft, on a reference card. A copy of
the approach diagram used by the pilot is at Appendix A.
The aerodrome controller advised the pilot of the possibility of
a holding pattern due to a preceding IFR aircraft being sequenced
for an instrument approach to runway 21. The controller
subsequently advised that holding would not be required if the
initial approach fix (SCHNC)2 was
reached not before 0825.
At about 0818, the aerodrome controller advised the pilot of the
preceding aircraft that the weather conditions in the area of the
final approach were a visibility of 5000 m and an approximate cloud
base of 1,000 ft.
At 0825 the aerodrome controller cleared the pilot of the King
Air to track the aircraft from the initial approach fix to the
intermediate fix (SCHNI) and to descend to not below 3,500 ft. The
published minimum crossing altitude was 3,600 ft. About one minute
later the pilot reported that he was leaving 5,500 ft and was
established inbound on the approach.
At 0828 the pilot reported approaching the intermediate fix and
3,500 ft. The controller advised that further descent was not
available until the preceding aircraft was visible from the
tower.
At 0829 the controller, having sighted the preceding aircraft,
cleared the pilot of the King Air to continue descent to 2,500 ft.
The pilot advised the controller that he was 2.2 NM from the final
approach fix (SCHNF). At that point an aircraft on a 3-degree
approach slope to the threshold would be at about 2,500 ft. The
controller then cleared the pilot for the runway 21 GPS approach,
effectively a clearance to descend as required.
The pilot subsequently explained that he was high on his planned
3-degree descent profile because separation with the preceding
aircraft resulted in a late descent clearance. He had hand flown
the approach, and although he recalled setting the altitude alerter
to the 3,500 ft and 2,500 ft clearance limits, he could not recall
setting the 580 ft MDA. He stated that he had not intended to
descend below the MDA until he was visual, and that he had started
to scan outside the cockpit at about 800 ft altitude in expectation
of becoming visual. The pilot recalled levelling the aircraft, but
a short time later experienced a 'sinking feeling'. That prompted
him to go-around by advancing the propeller and engine power
levers, and establishing the aircraft in a nose-up attitude. The
passenger in the right front seat reported experiencing a similar
'falling sensation' and observed the pilot's altimeter moving
rapidly 'down through 200 ft' before it stopped at about 50 ft. She
saw what looked like a beach and exclaimed 'land' about the same
time as the pilot applied power. The pilot felt a 'thump' just
after he had initiated the go-around. The passenger recalled
feeling a 'jolt' as the aircraft began to climb.
Figure 1. View of Coffs Harbour boat harbour
northern breakwater from north-east.
Witnesses on the northern breakwater of the Coffs Harbour boat
harbour observed an aircraft appear out of the heavy rain and mist
from the north-east. They reported that it seemed to strike the
breakwater wall and then passed over an adjacent restaurant at a
very low altitude before it was lost from sight. Wheels from the
left landing gear were seen to ricochet into the air and one of the
two wheels was seen to fall into the water. The other wheel was
found lodged among the rocks of the breakwater.
Figure 2. Northern breakwater of Coffs Harbour
boat harbour. King Air flight path was from left to right of
picture.
During the go-around the pilot unsuccessfully attempted to raise
the landing gear, so he reselected the landing gear selector to the
'down' position. He was unable to retract the wing flaps. It was
then that he experienced a strong g-force and realised that he was
in a turn. He saw that the primary attitude indicator had 'toppled'
and referred to the standby attitude indicator, which showed that
the aircraft was in a 70-degree right bank. He rapidly regained
control of the aircraft and turned it onto an easterly heading,
away from land. The inverter fail light illuminated but the pilot
did not recall any associated master warning annunciator. He then
selected the number-2 inverter to restore power to the primary
attitude indicator, and it commenced to operate normally. The pilot
observed that the left main landing gear had separated from the
aircraft. He continued to manoeuvre over water while awaiting an
improvement in weather conditions that would permit a visual
approach.
About 4 minutes after the King Air commenced the go-around, the
aerodrome controller received a telephone call advising that a
person at the Coffs Harbour boat harbour had witnessed an aircraft
flying low over the harbour, and that the aircraft had '…hit
something and the wheel came off'. The controller contacted the
pilot, who confirmed that the aircraft was damaged. The controller
declared a distress phase and activated the emergency response
services to position for the aircraft's landing. Witnesses reported
that the landing was smooth. As the aircraft came to rest on the
runway, foam was applied around the aircraft to minimise the
likelihood of fire. The occupants exited the aircraft through the
main cabin door.
Aircraft damage
The left main landing gear oleo strut was severed, consistent
with rapid rearwards bending. It was located in the water about 25
m to the north of the breakwater, with only one of the two wheels
attached. The other wheel was found among rocks at the base of the
breakwater. There were no impact marks on the tyres. The separation
of the left main landing gear from the aircraft damaged the left
inboard flap and resulted in an average flap asymmetry of 9
degrees. The impact force bent the right main landing gear
rearwards about 5 degrees, but it remained attached to the
aircraft. The nose landing gear and propellers displayed no
evidence of impact damage.
Figure 3. King Air on runway 21 at Coffs
Harbour.
The structural damage resulting from the impact with the sea or
reef was consistent with damage sustained in a heavy landing. The
impact forces damaged both engine nacelles and main landing gear
wheel wells. The wing centre-section outboard ribs rear of the main
spar and the lower fairing skins were buckled, and both ailerons
were buckled outboard of the inboard hinge points. All of the upper
and lower inboard wing assemblies were distorted. The inboard lower
fuel tank linings were wrinkled and some fuel tank lining skins
were cracked. The inboard wing leading edge upper skins were
cracked, and the left wing leading edge upper skin and stringer
were wrinkled.
The damage to the tips of the left propeller was consistent with
their contact with the runway during the subsequent landing. About
40 mm of the upper left landing gear was ground away during the
landing.
Pilot information
The pilot held an Air Transport Pilot (Aeroplane) Licence
endorsed with the aeroplane type, and held a Class 1 medical
certificate. He also held a command Instrument Rating (multi-engine
aeroplane) with approval to conduct GPS NPA procedures. He was
current on the aircraft type, and met GPS NPA recency requirements.
He had 18,638 hours total flying experience, which included 1,460
hours on type. He was familiar with operating into Coffs Harbour,
and had last flown there on the day prior to the occurrence
flight.
The pilot reported no physiological or psychological conditions
that may have affected his performance. He was within the limits of
the operator's prescribed flight and duty time limitations. He said
that he slept normally the previous night before rising at 0425 and
signing on for duty at 0600 for the scheduled 0700 departure.
Aircraft information
The aircraft was equipped and certified for single-pilot IFR
operations. Although the aircraft was fitted with an
NPA-capable3 Trimble 2101 GPS
receiver, there was no record of the Civil Aviation Safety
Authority (CASA) approval required to authorise conduct of GPS NPAs
in that particular aircraft. Installation of the GPS was consistent
with the CASA requirements that provided for non-precision approach
approval.4 However, that approval
required a specific supplement that was not incorporated into the
aircraft flight manual. Examination of the GPS receiver revealed
that it was capable of normal operation, and that its data card was
current at the time of the occurrence.
The counter drum-pointer altimeter5 on the pilot's instrument panel and the
three-pointer altimeter on the right panel were tested and found to
operate normally. Examination of the two independent static systems
found no water or obstructions. Functional tests did not reveal any
defects or anomalies. Both altimeter sub-scales were found set to
the appropriate aerodrome QNH.6
Radar data, recorded down to 3,600 ft, indicated appropriate
altitude keeping consistent with a correct QNH setting. Testing of
the vertical speed indicator did not reveal any defects or
anomalies.
The aircraft was equipped with an altitude alerting system to
provide the pilot with visual and aural warnings 1,000 ft before
reaching a preselected altitude and for deviations exceeding 300 ft
when at a preselected altitude. The altitude alerting system was
subsequently tested and found to operate normally.
The aircraft was fitted with a radio (radar) altimeter system
that measured actual height above terrain and was able to provide a
pilot with an alert when the aircraft reached a preselected height.
However, the radio altimeter system was inoperative. This was
recorded in the aircraft's maintenance release. The operator's B200
Minimum Equipment List (OMEL), which was approved by CASA,
permitted the dispatch of the aircraft without an operative radar
altimeter.
The aircraft had two inverters capable of independently
supplying power to the main attitude indicator. A master warning
and inverter inoperative annunciator indicated failure of an
inverter. Flags and full nose-up indication warned a pilot of
primary attitude indicator failure. Examination of the inverter
number-1 system revealed that its circuit breaker in the left wing
was open and, when reset during test, the system functioned
normally. The circuit breaker was in a poor condition and operated
erratically when tested. The investigation concluded that the
circuit breaker had tripped as a result of the impact, but could
not determine why there was no associated master warning.
The aircraft was fitted with an automatic flight control system
that was capable of controlling the aircraft during the final
approach of a GPS NPA.
The aircraft's automatic flight control system included a flight
director. When the autopilot was not engaged, the flight director
could be used to provide the pilot with attitude and pitch command
cues. With an altitude selected, and armed on the altitude alerting
system, the pilot would receive a main attitude indicator pitch
command to capture and maintain the preselected altitude.
The wing flap system incorporated a safety mechanism that
disconnected the power supply to the electric flap motor if any one
of the four flap surfaces was 3 to 6 degrees out of phase with the
other flaps. Failure of the flap to retract after the impact was
consistent with operation of that safety mechanism.
The retractable landing gear was electrically controlled and
hydraulically actuated. A safety switch on each main landing gear
prevented inadvertent gear retraction by opening the retraction
control circuit when weight was on the wheels. Failure of the
landing gear to retract after impact was consistent with
interruption of the retraction circuit resulting from the
disruption of the left main landing gear.
The aircraft was not fitted with a ground proximity warning
system, nor was it required to be.
Meteorological information
The Bureau of Meteorology (BoM) forecasts indicated that IMC
were to be expected in the Coffs Harbour area. The applicable area
forecast (ARFOR) predicted frequent showers over the sea and
coastal areas, with localised heavy falls. Moderate turbulence was
forecast below 5,000 ft. The Coffs Harbour aerodrome forecast (TAF)
predicted that there would be periods of up to an hour duration
when the visibility would reduce to 2,000 m in rain showers with
broken cloud at 1,000 ft.
The BoM weather radar imagery recorded at Grafton showed that
there were a number of large convective cells in the vicinity of
Coffs Harbour at the time of the occurrence. There was no
associated lightning activity, or any other indication of
thunderstorms. Steady rain had fallen in the area throughout the
morning prior to the occurrence and heavy rain was reported at the
aerodrome shortly after the pilot of the King Air executed the
go-around. During the morning, the recorded surface wind at the
aerodrome remained a constant light south-south-westerly of about 8
kts, gusting to 12 kts.
A BoM analysis of the weather data indicated that one or more
convective cells may have produced downdrafts that affected the
aircraft, but the magnitude of any downdrafts could not be
determined.
Witnesses sheltering at a caf on the northern breakwater near
where the aircraft impacted the surface related that, although
there was heavy rain, there were no significant wind gusts at the
time of, or immediately following, sighting the aircraft. However,
another witness who was working on a boat in the harbour reported
that an umbrella was overturned by an easterly wind just after he
observed the aircraft overfly the boat harbour.
The pilot commented that the descent and approach had been flown
almost entirely in cloud and rain showers with continuous moderate
turbulence. Although he had briefly sighted the water at the
commencement of the approach, he had not seen land or water
throughout the approach or go-around. The pilot indicated that
prior to joining the approach he had noticed some weather radar
returns, but the intended aircraft track was clear of those
areas.
The pilot of the preceding aircraft commenced a runway 21 VOR
instrument approach at about 2219. He advised that the heavy
showers on the outbound leg were the worst he had 'ever
experienced' and that his aircraft was still in cloud and rain on
arrival at the MDA.
The pilot in command of a Dash 8 aircraft which landed on runway
03 about 5 minutes after the pilot of the King Air executed the
go-around, reported that he could not see the far end of the runway
during the landing, and that there appeared to be '…a sheet or wall
of water' to the north of the aerodrome. That pilot also reported
that after shutdown, the rain '…was torrential'.
The Australian Transport Safety Bureau (ATSB) investigation into
a B737 microburst encounter during heavy rain conditions associated
with an intense thunderstorm at Brisbane on January 2001 (VH-TJX,
BO/200100213) highlighted that significant aerodynamic penalties
may be imposed on an aircraft during flight through heavy rain.
Those penalties can be sufficient to substantially degrade the
flight performance of an aircraft.
GPS Non-Precision Approaches
The GPS NPA provided the pilot with track guidance to the runway
via a series of pre-programmed waypoints. Track information was
displayed on the pilot's Horizontal Situation Indicator (HSI) as a
left or right deflection of a Course Deviation Indicator (CDI)
needle. In the absence of electronic vertical course guidance, a
series of descending steps, shown on the profile diagram of the
approach chart, provided the pilot with terrain clearance
guidance.
Civil Aviation Advisory Publications (CAAPs) provided
information on relevant regulatory requirements relating to a
variety of matters. The CAAPs were intended to aid in the
understanding of, and compliance with, regulatory requirements.
CAAP 178-1(0), published after the occurrence in October 2003,
provided information on non-precision approaches. In the
information relating to descent gradients, the following advice was
provided:
For an approach to be safe the descent gradient should be
neither too steep, nor too shallow. A steep approach requires high
rates of descent which are undesirable and increase the risk of
inadvertent descent below critical altitudes.
More specifically, Aeronautical Information Publication related
that:
Aircraft may commence a segment in excess of the specified
commencement altitude provided that any upper altitude limitation
is observed. However, rate of descent after the FAF [final approach
fix] should not normally exceed 1,000 ft/min.
CAAP 178-1(0) also included advice that the International Civil
Aviation Organization has:
… identified that many CFIT [controlled flight into terrain]
accidents have occurred because pilots did not possess good
situational awareness in regard to terrain beneath the approach
flight path …
Controlled flight into terrain and approach-and-landing
accident risk
Controlled Flight into Terrain occurs when an airworthy aircraft
under the control of the flight crew is flown unintentionally into
terrain, obstacles or water, usually with no prior awareness by the
crew. According to the Flight Safety Foundation (FSF), CFIT is
currently the greatest threat to air safety and is the primary
causal event in the approach and landing accidents studied by the
FSF Approach and Landing Accident Reduction (ALAR) Task
Force.7 FSF analysis of 287 fatal
approach-and-landing accidents between 1980 and 1996 showed that,
of the accidents where data was available, 75 percent happened
where a precision approach aid was not available or was not
used.8
The consequences of CFIT are normally severe to catastrophic in
terms of loss of life or severe injury and damage to property
and/or the environment. All flights can be considered to be at
moderate risk of CFIT, based on historical data relating to the
frequency and consequences of CFIT accidents. As risk is dependent
on consequences and likelihood of an event, the only way that CFIT
risk can be reduced is for operators to ensure that the necessary
defences are present to reduce its likelihood.
The ATSB has recently completed two investigations into CFIT
accidents that involved destruction of the aircraft and loss of
life to aircraft occupants (VH-FMN at Mt Gambier, BO/200105769 and
IL-76 at Timor, BO/200300263). Both investigations referred to the
FSF initiatives in approach-and-landing accident reduction, and the
FSF checklist to evaluate CFIT risk as part of its international
program to reduce CFIT events that present risk to aircraft, crews,
and passengers.
The FSF ALAR Task Force has concluded, amongst other things,
that:
- establishing and adhering to adequate standard operating
procedures (SOPs) and crew decision-making processes improve
approach-and-landing safety
- failure to recognise the need for a missed approach and failure
to execute a missed approach is a major cause of
approach-and-landing accidents
- unstabilised and rushed approaches contribute to
approach-and-landing accidents (FSF definition of stabilised
approach is at Appendix B)
- the risk of approach-and-landing accidents increases in
operations conducted in low light and poor visibility
- effective use of radio altimeters will help to prevent
approach-and-landing accidents.
An ALAR Tool Kit, which comprised a unique set of pilot briefing
notes, videos, presentations, risk-awareness checklists and other
tools on compact disc is available from the FSF. In a news release,
dated March 2003, the FSF expressed concern that, not everyone in
the industry had taken note of the ALAR work.
Air traffic control approach procedures
The Manual of Air Traffic Services (MATS) Part 6.2.6, Approach
Clearances, stated that:
Unless authorised to make a visual approach, an IFR flight must
conform to the published instrument approach procedure nominated by
ATC.
A controller shall not issue an air traffic clearance which
authorises or requires a pilot to descend in IMC below the lowest
safe altitude for the route segment in a manner different from that
specified in:
a. … GPS Arrival procedures
b. the procedures, plan and profile diagram of IAL [instrument
approach and landing charts] charts published in AIP/FLIP Terminal
…
MATS Part 3.4.2 further stated that:
When an aircraft will make an instrument approach, clearance for
the approach should be issued at least 3 minutes before the
procedure is expected to commence, or as a soon as conditions
allow.
MATS Part 6.12.14 also noted that a temporary level restriction
during an instrument approach can only be applied to civilian
aircraft during practice [instrument] approaches in Visual
Meteorological Conditions.
A clearance to conduct a GPS instrument approach authorises a
pilot to descend from the IAF altitude to the minimum descent
altitude and to continue to the airport for landing if visual, or
to make a missed approach if unable to land or the pilot cannot see
the airport.
Operator information
The operator was an aeromedical service provider that was
contracted to provide crews and aircraft maintenance services for a
24-hour, all weather, aerial ambulance service based at Sydney
airport. Instrument approaches promulgated for aerodromes in NSW
were non-precision approaches except for Instrument Landing System
(ILS) approaches at Sydney and Tamworth.
With regard to formal CFIT risk management at the time of the
occurrence the operator reported that:
Pilots are required to watch the CFIT video which is viewed on
appointment and annually as part of the recurrent training program.
The pilots are issued with the CFIT brochures and checklist. The
ALAR Tool Kit has not been used in the past.
The operator advised that, following the Mt Gambier CFIT
accident involving VH-FMN (BO/200105769), the following action was
initiated:
Synopsis of accident and conditions … included in February 2002
safety report
Flight Safety Foundation CFIT checklist conducted February 2002.
Report and recommendations circulated by Aviation Safety Officer
and adopted by Aviation Manager/Check & Training pilots.
All aircraft fitted with Flight Profile Annunciators
The operator's documented standard operating procedures did not
specifically address, or were considered to be unclear in relation
to, the following:
- Stabilised approach parameters
- Go-around and missed approach policy
- Use of radio altimeter in conduct of non-precision
approaches
- Use of flight director in conduct of non-precision
approaches
- Use of autopilot in conduct of non-precision approaches.
1 Raytheon Aircraft
Company superseded the Beech Aircraft Corporation as the
manufacturer of King Airs.
2 Approach fixes are given
a five letter designator to identify the fix in the GPS database
and on the approach diagram. A copy of the approach diagram is at
Appendix A.
3 TSO-C129 Class A1.
4 Airworthiness directive
AD/RAD/61 GPS Installation for Non-Precision Approaches required
compliance with Civil Aviation Advisory Publication (CAAP)
35-1(0).
5 Type of altimeter
recommended in Annex 6 of Convention on International Civil
Aviation (Chicago 1944) for aeroplanes operated in accordance with
instrument flight rules.
6 The barometric pressure
in hectopascals that enables an altimeter to show height above mean
sea level.
7 Appendix A of the Flight
Safety Foundation, Approach-and-Landing Accident Reduction Task
Force, Operations and Training Working Group, Final Report (Version
2.0).
8 Flight Safety
Foundation, Approach-and-Landing Accident Reduction Task Force,
Analysis of Critical Factors During Approach and Landing in
Accidents and Normal Flight, Data Acquisition and Analysis Working
Group, Final Report (Version 2.0).
