Level Bust - Pilot Induced Situations

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Article Information
Category:	Level Bust
Content source:	SKYbrary
Content control:	EUROCONTROL

Contents 1 Description 2 Typical Scenarios 3 Contributory Factors 4 Solutions 5 Further Reading

Description

Situations sometimes occur in which the pilot receives and apparently understands a flight clearance, but fails to follow that clearance, leading to a level bust. This can happen even when the pilot has correctly read back the clearance and when there are no unusual circumstances

Typical Scenarios

• The pilot confuses the altitude with another element of the message, for example:
  • Flight is cleared to climb to FL220 at an airspeed of 200 kt and climbs to FL200; or,
  • Flight is given a radar heading of 210 deg. and descends to FL210.
• The pilot is expecting clearance to a particular flight level or altitude, because that was the level requested or because that is the usual clearance given. The pilot does not consciously notice the difference and climbs or descends to the expected level even though the correct level was read back. This can even happen when the cleared level has been written down.
• The pilot is distracted by, for example, irrelevant talk on the flight deck or bad weather, or an abnormal or emergency situation.
• The normal crew cross-checking procedure does not take place so that, for example, the PNF fails to notice that the PF is levelling the aircraft at the wrong flight level or altitude. This can occur if a vertical clearance has been received while the PNF (or other flight deck crew member with monitoring responsibilities) is off-frequency (perhaps making a company call or visiting the washroom).

Contributory Factors

• Pilot work-load;
• Interruption or Distraction;
• Emergency or Abnormal Situation.

Solutions

• Improve standard of pilot training, especially in:
  • Air-Ground Communication Safety;
  • Loss of Situational Awareness;
  • Crew Resource Management;
• Adherence to SOPs, especially the Sterile Cockpit principle if applicable.

Further Reading

EUROCONTROL Level Bust Toolkit

• European Action Plan for the Prevention of Level Bust, especially the folowing Briefing Notes:

• Level Bust Briefing Note Gen 1 - Level Busts: Overview;
• Level Bust Briefing Note Gen 2 - Pilot-Controller Communications;
• Level Bust Briefing Note Gen 3 - Call Sign Confusion;
• Level Bust Briefing Note Ops 1 - SOPs;
• Level Bust Briefing Note Ops 2 - Altimeter Setting Procedures;
• Level Bust Briefing Note Ops 3 - Standard Calls;
• Level Bust Briefing Note Ops 4 - Aircraft Technical Equipment;
• Level Bust Briefing Note Ops 5 - ACAS;
• Level Bust Briefing Note Ops 6 - Human Factors;

• HindSight 10: The tenth edition of HindSight, titled "Level Bust or... Altitude Deviation ?", published in December 2009, contains a variety or articles addressing different aspects of the Level Bust issue. These and other Level Bust products are listed in the article Level Bust Products

Airbus

• Airbus Supplementary Briefing Note - Preventing Altitude Deviations and Level Busts;