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Loss of Separation During Go-around

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Article Information
Category: Loss of Separation Loss of Separation
Content source: SKYbrary About SKYbrary
Content control: EUROCONTROL EUROCONTROL


Description

Go-around, although a relatively infrequent occurrence, is a normal phase of flight and pilots should be encouraged to go-around when conditions demand. However, promoting go-around as a normal flight phase does not mean that there are no safety issues associated with it.

According to the Findings and Conclusions of the Go-around Safety Forum [1], the majority of accidents over the last 10 years have occurred during the approach, landing and go-around flight phases. One in ten go-around reports records a potentially hazardous go-around outcome, including exceeded aircraft performance limitations, fuel endurance issues or loss of separation. Although runway excursion accident numbers are much higher than go-around accidents, it is the go-around accidents that are, percentage wise, more fatal.

Factors Leading to Loss of Separation During Go-around

  • Lack of clear responsibility, between APP and TWR, for coordination and separation of go-around aircraft
  • Lack of procedural de-confliction of the missed approach path from other traffic including traffic departing from another runway and wake vortex de-confliction for parallel runways
  • Complex missed approach procedure – e.g. conditional go-around procedure
  • More than one missed approach procedure for each runway
  • Late issue or use of unpublished go-around instructions
  • Lack of safe traffic management procedures for late (after DA/MDA) go-around
  • The height at which a go-around is initiated during an approach presents different challenges and risks
  • Failure to fly the required track can lead to Controlled Flight Into Terrain (CFIT) or loss of separation
  • Wake turbulence generated may create a hazard to another aircraft that can lead to loss of control and, potentially, loss of separation
  • The safety of a go-around is compromised by a delay in the go-around decision
  • Due to rapidly changing weather and RWY conditions, pilot expectation at commencement of the approach and the actual conditions at the decision point may be significantly different

Defences

The first phase of the missed approach procedure is always associated with high workload in the cockpit as simultaneous, coordinated changes in pitch, thrust and configuration must occur as the aircraft is transitioned from the approach to the missed approach profile. The flight crew expects to follow the missed approach procedure laterally and vertically and had prepared for that profile during their briefing. If the standard missed approach flight path has to be changed for operational reasons by air traffic control, the flight crew should be advised as early as possible; ideally before, or at an early stage of, the approach to allow them time to prepare themselves accordingly.

Other defences that help prevent loss of separation during the missed approach include:

  • Issuing ATC instructions for vertical or lateral avoiding manoeuvres to an aircraft during the first phase of a missed approach (up to approx. 2000 ft/AGL) should be avoided (i.e. shall not be used as a routine procedure for traffic separation).
  • The potential for traffic and/or wake vortex conflict during a go around is sometimes reduced if situational awareness of other traffic in the vicinity is available to pilots.
  • Flight crew should receive updated weather and RWY conditions information on final approach. Contingency arrangements/procedures should exist for use in windshear conditions.
  • Pilots should understand that go-around from below minimums or from the low energy regime (baulked landing) carries a greater risk than a go-around at or before published minima.
  • Go-Around training should include a range of operational scenarios, including go-arounds from positions other than DA/MDA and the designated Stabilised Approach Gate. Scenarios should involve realistic simulation of surprise, typical landing weights and full power go-arounds
  • In high density environments, procedures which allow same-frequency communication with aircraft operating in languages other than English should be reviewed (safety assessed)to establish if they can contribute to loss of pilot situational awareness of potentially conflicting traffic during go-arounds.
  • The organisation responsible for procedure design should ensure that straightforward go-around procedures are available and published for each runway, The go-around procedures should be designed in consultation with pilots who will be expected to fly them.
  • Aircraft Operators and ATC should improve their mutual understanding of the other’s go-around practices/procedures.

Safety Occurrences on SKYbrary

  • B738/B738, vicinity Oslo Norway, 2012 (LOS HF AGC) - On 31 October 2012 a Boeing 737-800 (LN-DYC) being operated by Norwegian Air Shuttle on a scheduled passenger flight from Trondheim to Oslo as NAX 741 lost separation in day IMC against another Boeing 737-800 (LN-NOM) also being operated by Norwegian Air Shuttle on a scheduled passenger flight from Oslo to Trondheim as NAX 740 after the former had advised that a go around was being flown from the approach to the same runway from which the other aircraft had just departed.
  • A318/B739, vicinity Amsterdam Netherlands, 2007 (LOS HF) - On 6 December 2007 an Airbus A318 being operated by Air France on a scheduled passenger flight from Lyon to Amsterdam carried out missed approach from runway 18C at destination and lost separation in night VMC against a Boeing 737-900 being operated by KLM on a scheduled passenger flight from Amsterdam to London Heathrow which had just departed from runway 24.
  • A332 / RJ1H, vicinity Zurich Switzerland, 2004 (LOS HF) - On 31 October 2004, a Loss of Separation occurred between an A330-200, on a low go-around from Rwy 14 at Zurich Switzerland, and an Avro RJ100 which had been cleared for take-off on Rwy 10 and was on a convergent flight path.
  • B737 / B737, vicinity Geneva Switzerland, 2006 (LOS HF) - On 11 May 2006, loss of separation occurred between a B737-700 taking off from Geneva and another B737-700 configured as a Boeing Business Jet (BBJ) which had commenced a go around from the same runway following an unstabilised approach. The speed of the BBJ was such that it rapidly caught up with the departing 737.

References

  1. ^ The Go-around Safety Forum took place on 18 June 2013 at EUROCONTROL Brussels. The Findings and Conclusions Issued 26 June 2013 are available in Further Reading

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Further Reading