Vertical efficiency in descent: assessing the potential for improvements at the top 30 European airports

This paper presents an analysis of the factors affecting vertical efficiency in the descent phase at the top 30 European airports. The motivation is to identify, for each airport, the nature of the potential sources for improvement, in particular those actionable locally within the terminal area. The analysis focusses on the last 50NM area and relies on one year of data (2019) with more than 2.5 million flights. The analysis reveals globally that for a median flight time of 14.6 minutes (1) the entry conditions at 50NM generates an inefficiency in the order of 900ft compared to 2250ft inside 50NM; (2) the horizontal inefficiency induces an increase of the vertical inefficiency of 850ft per min; (3) airspace and operations generates an inefficiency of respectively 650ft and 1450ft. Focusing on operations, and considering each airport with an analysis per flights, the analysis also reveals: an increase of the vertical deviation with the horizontal deviation (950ft per min), and a dispersion of the vertical deviation for a same horizontal deviation (interquartile difference of 2150ft). A further decomposition below / above FL65 enabled to assess the effect of a continuous descent procedure with a limited deviation below FL65. Two recommendations actionable locally within the terminal area may be envisaged: reduction of the dispersion by reinforcing the adherence to best local practices and systematisation of the working methods; reduction of the increase by using a sequencing technique to facilitate continuous descent. Beyond, the analysis reveals a very significant disparity among airports, with some indicators ranging by a factor of 5 or more. This would suggest a potential for significant improvements in particular at airports showing a significant inefficiencies, to be explored further with local staff.