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Weather Scenario: Thunderstorms At Syd Airport

Brief

The airline is a domestic carrier in Australia. The fleet consists of five twin- engine, wide-body aircraft (registrations/tails designated WBA-WBE), and nine twin-engine narrow-body (single-aisle) aircraft (registrations designated NBL-NBT). The capacity of the wide-body aircraft is 300 seats and the narrow-body aircraft 180 seats. Minimum turnaround time between passenger flights for wide-body aircraft is 60 minutes and for narrow-body aircraft is 35 minutes.

Refer to Figure 7.1 opposite.

Scenario Description

The time is 1115 EST (SYD) Time. Several lines of severe thunderstorms are approaching SYD. The IOC’s Meteorological section has been aware of imminent thunderstorms during the morning and forewarned of the most likely impact time. Previously issued terminal area forecasts (TAFs) indicate that from 1130-1230, SYD can expect sustained winds from the west in excess of 40 knots as a frontal system moves through. In addition, low cloud, heavy rain, lightning on and around the airport and severe turbulence below 5000 ft can be expected. The current METAR indicates variable winds favouring the north from 15-20 knots. Accordingly, the two parallel runways, 34L and 34R are currently in use. Aircraft en route to SYD and due to arrive from 1030 onwards, have been required to carry sufficient fuel to be able to divert to an alternate airport (alternate fuel).

Ioc Interaction

The airline’s SYD Port Coordinator has advised that thunderstorms are expected in the immediate SYD area in the next 15 minutes. She has established that NBQ 380 HBA-SYD and WBC 212 MEL-SYD are currently holding south of SYD, and NBO 361 OOL-SYD is holding to the north, but no further information is available yet. Further, she advised that АТС are expecting the winds to change, and aircraft are likely to be held further while the front passes through. Currently, aircraft are departing SYD without delay, and aircraft have been landing on both the parallel runways.

The immediate concern in the IOC is for flights about to arrive into SYD, and then for others that are already en route, but not yet in the vicinity. A full scan of the utilisation reveals the considerable number of aircraft close to SYD (refer to Figure 7.1). The scan not only looks at the imminent arrivals but extends across each pattern to assess the potential consequential impact should they be disrupted. The standout information will include the amounts of ground time (where delays may get absorbed), patterns leading to curfews (e.g., WBA (SYD), WBE (ADL), NBM (SYD), NBN (SYD), NBO (SYD) and NBR (OOL)), and any irregular flights (e.g., charters, ferry flights or international operations), as these may require specific attention (e.e., NBM operating BNE-NOU-SYD). ’

Information needs to be established about each of the inbound aircraft, from two points of view. The first is to establish a likely sequence of approaches from АТС, which will assist the IOC in determining which aircraft are likely to land first, such that departures can be prioritised. The second concerns the identification of longer haul inbound aircraft that may not be able to hold for very long. The questions are likely to include the following:

  • a) Where is each aircraft (i.e., on descent, approach or already in a holding pattern)?
  • b) What fuel is each carrying?
  • c) How long can each hold?
  • d) What alternate has each nominated?

The received information may reveal the status of many of the aircraft, but often the information comes through spasmodically, or not at all (everyone is busy at this time - especially АТС), in which case it must be sought from the appropriate area. In this scenario, the following information (in order of scheduled arrival time) has now been ascertained by the Port Coordinator and advised to the IOC at 1120:

  • a) NBQ 380 HBA-SYD (due at 1110) has been given 20 mins holding south of the field. NBQ has 20 mins of holding fuel before having to divert using CBR as its alternate.
  • b) NBO 361 OOL-SYD (due at 1120) has been given 15 mins holding north of the field, and has 30 mins of holding fuel before having to divert using OOL as its alternate.
  • c) WBC 212 MEL-SYD (due at 1125) has been given 15 mins holding south of the field, and has 40 mins of holding fuel before having to divert using MEL as its alternate.
  • d) NBR 391 HTI-SYD (due at 1130) has been given 30 mins holding north of the field, and has 45 mins of holding fuel before having to divert using OOL as its alternate.
  • e) NBN 322 CBR-SYD (due at 1150) has been given 35 mins holding south-west of the field, and has 60 mins of holding fuel before having to divert using CBR as its alternate.
  • f) NBM 341 CNS-SYD (due at 1155) has been given 40 mins holding north of the field, and has 35 mins of holding fuel before having to divert using OOL as its alternate.
  • g) WBB 271 ADL-SYD (due at 1205) has been given 30 mins holding west of the field, and has 60 mins of holding fuel before having to divert using BNE as its alternate.
SYD weather - status @ 1120

Figure 7.2 SYD weather - status @ 1120

  • h) YVBE 214 MEL-SYD (due at 1225) has been told by АТС to expect 20 mins holding west of the field. WBE has just got airborne at MEL and has 50 mins of holding fuel before having to divert using MEL as its alternate.
  • i) WBA 303 BNE-SYD (due at 1235) has been told by АТС to expect 15 mins holding. WBA has just got airborne at BNE and has 65 mins of holding fuel before having to divert using BNE as its alternate.

With this information the IOC can start to address potential delays likely to affect the network.

Figure 7.2 opposite reflects the holding times above.

Of immediate concern are the first aircraft due into SYD, with NBQ (ETA 1130), NBO (ETA 1135) and WBC (ETA 1140), being given short holding times. Elowever, the information received about NBM’s status is of immediate concern, as the aircraft has been given 40 minutes holding which is in excess of its 35 minutes reserve fuel. Thus, the IOC will need to clarify this information, and if correct, need to establish the intention of the crew. This would be achieved via the Port Coordinator, direct with АТС, or direct with the crew by radio (contacting the crew when their workload is high may be difficult, so sometimes a relay through АТС is necessary). A further consideration is whether the aircraft is able to hold for longer using a different alternate. In other words, can the aircraft use a closer diversion port which would increase its holding time? Also of concern are the next aircraft commitments for those that have been given holding. In particular, WBE 306 SYD-BNE, NBM 304 SYD-BNE, NBN 382 SYD-HTI and NBO 323 SYD-CBR will potentially be delayed as the utilisation currently stands (i.e., no aircraft swaps made).

 
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