At 1718 ESuT On 5 November 2002, VH-TJG, a Boeing 737-476
aircraft, encountered turbulence 1718 ESuT during the landing flare
on runway 35 at Canberra International Airport. The aircraft was
operating a scheduled fare-paying passenger service from Melbourne,
Victoria to Canberra, ACT. The pilot in command was the handling
pilot for the flight.
At 1700, the wind direction and speed at Canberra was 280
degrees T at 18 kts, gusting to 23 kts. At 1730, it was 280 degrees
T at 18 kts, gusting to 26 kts. Runway 35 was aligned on magnetic
heading 348 degrees, which was equivalent to 360 degrees T.
The automatic terminal information service (ATIS) at Canberra
airport provided information on the prevailing weather conditions.
At the time of the occurrence, information "Sierra" was current. It
included information that runway 35 was in use, and that the wind
direction and speed was 270 degrees M, with a minimum speed of 15
kts and maximum speed of 25 kts.
The aircraft was equipped with a solid-state digital flight data
recorder (SSFDR). The flight data plots revealed that the pilot in
command applied left control wheel to achieve a left wing low
attitude of about 3 degrees as the aircraft descended through a
radio altitude of about 60 ft. At about 6 ft radio altitude, the
aircraft suddenly rolled left to a left wing low attitude of about
6 degrees, and the pilot in command rapidly applied right control
wheel input to arrest the roll to the left. The aircraft landed
about one second later in a slightly right wing low attitude.
The landing was completed without further incident, and there
were no reported injuries to any of the 34 occupants of the
aircraft.
The pilot in command subsequently reported that the turbulence
encountered during the landing flare appeared to have resulted from
a hangar located adjacent to, and to the west of, the touchdown
zone of runway 35.
Construction of the hangar was completed in April 2002. The
airside (eastern) face of the hangar was located 283.5 metres from
the centreline of runway 35, and the roof height on the airside
face of the hangar was 21.7 metres.
Turbulent wake eddies may be generated downwind of obstacles by
wind flowing over and around them. The turbulent effects will
depend on the size and location of an obstacle or group of
obstacles, such as a cluster of buildings, as well as the direction
and speed of the wind. If obstacles are located close to runways,
turbulent wake eddies from those obstacles may have the potential
to affect safety of flight if they result in aircraft experiencing
difficulties during takeoff or landing.
The International Civil Aviation Organization (ICAO) has
published standards and recommended practices that relate to
aircraft, personnel, airways and auxiliary services. Those
standards and recommended practices are contained in various
Annexes to the Convention on International Civil Aviation, which
was signed at Chicago on 7 December 1944 (the Chicago Convention).
Australia is a contracting State to the convention. It is obliged
under Article 37 of the convention to conform to standards and to
endeavour to conform to recommended practices unless a difference
has been filed with ICAO.
Annex 11 contained the standards and recommended practices that
relate to the provision of air traffic services to the aviation
sector. Paragraph 4.3.7 of Annex 11 detailed the information to be
included in ATIS messages, and paragraph 4.3.7 k) required that
messages contain:
`…other essential operational information.'
Paragraph 4.3.7 s) required ATIS messages to contain:
`…any available information on significant meteorological
phenomena in the approach, take-off and climb-out areas including
wind shear, and information on recent weather of operational
significance.'
ATIS "Sierra" contained no information regarding the likelihood
of turbulence in the touchdown zone of runway 35 at the time of the
occurrence.
Canberra International Airport is a licensed aerodrome, and
particulars about the aerodrome are required to be published in the
Aeronautical Information Publication (AIP) Enroute Supplement
Australia (ERSA).
The Civil Aviation Safety Authority (CASA) publishes Civil
Aviation Advisory Publications (CAAPs) which provide guidance on
the preferred method for complying with the Civil Aviation
Regulations. CAAP 89O-1 (2), issued in November 2000, related to
publishing aerodrome information and reporting changes to that
information. That information included any event that affected the
safety of aircraft using the aerodrome.
At the time of the occurrence, both the ERSA and the location
briefing material for Canberra aerodrome contained no information
to caution pilots of the likelihood of turbulence from the hangar
located adjacent to, and to the west of, the touchdown zone of
runway 35.
There have been two similar events of building-induced
turbulence in the UK. One resulted in a B747 leaving the runway at
London Heathrow airport, and was described in the UK Air Accident
Investigation Branch (AAIB) Bulletin No. 5/2002. The other involved
an A300 that sustained a podstrike at London Gatwick airport, and
was described in AAIB Bulletin No. 6/2002.
The National Transportation Safety Board (NTSB) of the USA has
had no reported occurrences of building-induced turbulence, nor has
the NTSB identified that condition as a safety concern.
There are presently no building codes or standards in Australia
that address the phenomena of building-induced turbulence with
respect to proposed buildings to be located on or adjacent to
aerodromes.
