By far the most prevalent cause of level busts since 2004 is correct pilot readback of a cleared flight level followed by incorrect action by the crew, says the UK Civil Aviation Authority’s flight operations department. The CAA is worried that despite active level-bust prevention programmes, including distribution of a “Eurocontrol level-bust toolkit” via the internet and a CD, the causal factors and prevalence remain virtually unaffected.

Level busts occur when an aircraft deviates from its cleared level by more than 300ft (100m), often by continuing a cleared climb or descent before the error is recognised. The CAA has published a communication reminding crews of the multiple procedural and decision-making components involved in receiving a clearance and carrying it out, including altimeter setting procedures, and suggests outline standard operating procedures for adoption into airline manuals and training.

Correct pilot readback of a clearance followed by incorrect action is twice as common as any other type of level-bust. Misheard clearances and incorrect following of cleared standard instrument departures come next.


Source: Flight International