Deutsche Flugsicherung (DFS) contracted DNV to conduct a safety assessment on a proposed option for optimising separation on final approach into Frankfurt Main Airport. The proposal was for a new concept that deviated from ICAO accepted standards.
Satisfying increasing demand for air travel is a key issue at major airports. Already operating at near capacity and with the building of another runway years away, the only option at Frankfurt Main for increasing capacity was to improve the utilisation of existing runways.
DFS had developed a number of innovative options for increasing capacity but it was critical that the safety implications of any changes were assessed fully so that risk could be effectively managed. The air navigation service provider also needed regulatory approval for any deviations from ICAO accepted practices and standards.
One option was the reduction of diagonal separation between staggered approaches on Frankfurt’s parallel runways inside the outer marker. The 518 metres lateral spacing of these runways was to be used as an enabler for the reduced longitudinal separation. The effectiveness of this spacing in reducing collision and wake vortex risk needed to be assessed.
DNV assessed the safety of the proposed system in two phases. These were:
safety assessment of the concept – was it safe with respect to wake vortex and collision
risks?assessment of detailed operational hazards.
Specifically designed modules were used to make quantitative estimates of wake vortex risk, in which the measured distributions of aircraft were key inputs. A relative risk assessment was conducted in which the risks for RDSM were compared to safety levels associated with ICAO accepted practices.
This modelling showed that the risks of the RDSM concept were no higher than equivalent ICAO intrail scenarios. The analysis of detailed operational hazards involved structured brainstorming of what could go wrong in each flight phase.
Pilots, controllers, system designers and safety experts were facilitated by DNV to identify hazards and then assess the severity of their effects and their likelihood. This enabled their risks to be compared to Deutsche Flugsicherung standards.
As a result of this study, DFS and its partners have been able to safely introduce capacity enhancement measures into Frankfurt Main Airport. The safety assessment helped DFS identify measures for ensuring that risk had been reduced as far as reasonably practicable. It also improved stakeholder awareness of safety issues and ultimately acceptance of the proposed change.