Dual Diagonal Approaches

Direct-Track was selected to provide operational expertise in the development of the Safety Case associated with the Dual Diagonal (DD) Approach concept at Dubai International Airport.

The Dual Diagonal concept is based on straight in approaches to parallel runways laterally separated by only 386 meters.  This configuration has caused problems for the airport as it wants to increase runway arrival capacity by allowing landings on both runways simultaneously. Current ICAO wake turbulence rules dictate that the two runways at Dubai must be considered as a single runway for wake turbulence application.  This restriction limits the use of the right hand runway as irrespective of the type of aircraft single runway wake turbulence spacing is to be applied.

The geometry of the runways has the threshold of the right hand runway inset by over 1000 meters.  This factor has been taken into account and by projecting the descent profile back from the runways, the profile of the aircraft on the right hand runway is always above the descent profile of the aircraft on the left.  Using this fact and the accepted logic of wake always descending, the case is being made that less than ICAO spacing is appropriate as the flight paths will never cross and therefore wake transference will not be a factor.

Specialist wake vortex analysis is being carried out using LIDAR technology to support the assumptions.