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Analysis

Summary

2.1 Introduction

The occurrence involving EAL involved a number of issues including the limitations of airborne weather radar, the mutual exchange of information between BoM and air traffic control, and provision of information to the B767 crew. Further, the occurrence involving EAL displayed a number of similarities with a Boeing 737 microburst encounter at Brisbane Airport on 18 January 2001.

2.2 The aircraft

2.2.1 Aircraft weather radar

The aircraft weather radar did not have the capability to provide predictive forward-looking windshear detection and avoidance information to the crew, nor was there a requirement for it to do so. That capability would have provided an early alert to the crew about the hazardous conditions that existed ahead of the aircraft and may have assisted them to avoid or minimise those hazards.

The presence of red or magenta on the aircraft weather radar display is a measure of rainfall intensity. The crew reported areas of red on the display, with no hooks, fingers, contours, scalloped edges or U-shaped returns that could have indicated the presence of hail or other adverse weather conditions. In addition, they reported that they assessed the areas of red on the weather radar display as heavy rain only. The crew could see heavy rain approaching the aerodrome, but were not aware of any associated adverse weather conditions, such as thunderstorm activity and hail. In the absence of any indications of adverse weather from either the aircraft weather radar or ATS, they would have been unaware of the presence of adverse weather conditions in the takeoff flight path.

2.2.2 Aircraft flight path

The crew reported that they increased thrust in accordance with the operator's published windshear escape manoeuvre. However, recorded FDR data indicated that, throughout the windshear encounter, both EPR and thrust lever angle (TLA) remained in the take-off position until climb thrust was set when clear of the encounter. The investigation was unable to resolve the discrepancy.

2.2.3 Other aircraft movements

A number of other aircraft movements into and out of Coolangatta Airport occurred in the short time before EAL took off. None of those aircraft reported encountering adverse weather, including the Boeing 737 that took off from runway 32 about 15 minutes before EAL was issued clearance to takeoff from the same runway. The absence of any reports of adverse weather encounters likely contributed to the crew of EAL assessing that the weather conditions that they could see visually, and which were displayed on the aircraft weather radar, consisted of heavy rain only.

2.3 Organisational issues

2.3.1 Bureau of Meteorology

The BoM reported that the thunderstorm encountered by EAL developed in a short time-frame ahead of the main line of thunderstorms. Forecasters became aware of the severity of the thunderstorm 9 minutes before EAL was cleared to take-off. Despite observing the storm cell move towards and pass over Coolangatta aerodrome, forecasters did not contact Coolangatta ATS to advise of the approaching hazardous weather.

2.3.2 Air Traffic Services

ATIS Echo was current until 1337:41. ATIS Foxtrot was issued at 1338:22. The crew requested taxi clearance, notifying receipt of ATIS Echo, 45 seconds after ATIS Foxtrot was issued. Accordingly, the crew had not been advised that thunderstorms were present within 5 NM of Coolangatta Airport.

The SMC controller did not inform the crew that the ATIS had changed and did not advise the crew of the change in weather conditions. Accordingly, an opportunity was missed to provide the crew with updated information of the prevailing meteorological conditions at the time that the aircraft was intending to take-off.

Coolangatta ATS controllers could see that the thunderstorm was approaching and that weather conditions were deteriorating, however, they did not contact BoM staff to ascertain the severity of the approaching weather. Consequently, neither BoM nor Coolangatta controllers had a complete picture of the deteriorating meteorological situation. In turn, the crew of EAL was not provided with a complete picture of the meteorological situation in the vicinity of Coolangatta Airport and their intended departure flight path.

Coolangatta ATS reported that they had access to the BoM PC-based METRAD/RAPIC display. Controllers were aware that information depicted on those displays could be up to 10 minutes behind actual time. Due to the rapid development of the thunderstorm cell encountered by EAL, the investigation was unable to confirm if the METRAD/RAPIC display would have been able to provide Coolangatta controllers with sufficient information to advise the crew of EAL of approaching hazardous weather.

2.4 Previous occurrence

The occurrence involving EAL displayed a number of similarities to a Boeing 737 microburst encounter that occurred at Brisbane Airport on 18 January 2001. The circumstances of the occurrence involving EAL indicate that the ATSB recommendations published in ATSB investigation report BO/200100213 remain valid.

 
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