A side-step manoeuvre, allowed by some NAAs, is an Instrument Flight Rules (IFR) approach profile to closely spaced parallel runways in which the aircraft conducts the approach to one of the runways but lands on the other.
There can be many reasons for conducting side-step operations, some which benefit the operator, some ATS and some both parties. In many cases, the utilization plan for close parallel runways has one runway designated for arrival and the other for departure. In this circumstance, there might only be a published instrument approach to one of the two runways. Even in Instrument Meteorological Conditions (IMC), side-step manoeuvres can allow utilisation of both runways for landing when operationally necessary; for example, when the runway serviced by the instrument approach is closed for maintenance. Similarly, if there is an approach procedure to each runway but one is out-of-service, side-step continues to allow the use of both runways for arrival operations. These profiles enhance ATC capability in the event of an outage or closure. With only a single approach in service, there might also be a operator desire for their aircraft to exit the runway in a particular direction. This could be the case if the commercial terminal was on one side of the runway pair but the General Aviation or Military facilities were on the other. In this circumstance, inbound aircraft, conducting the same approach, could be cleared to land on the runway which best facilitates access to their planned destination on the aerodrome. In this case, a side-step profile can reduce the delays, the ATC coordination requirements, and the risks, associated with a taxying aircraft needing o cross an active runway.
Side-step manoeuvres are only permitted on parallel runways that are separated by 1200' or less. Where side-step manoeuvres are authorised, ATC may clear an aircraft to conduct a standard instrument approach procedure to either one of the parallel runways to be followed by a straight−in landing on the adjacent runway. The ATC clearance will specify the approach procedure to be flown as well as the landing runway. For example, "cleared ILS approach runway 26 left, side-step to runway 26 right", or similar wording. Pilots are expected to commence the side−step manoeuvre as soon as possible after the runway or runway environment is in sight. Compliance with any minimum altitudes, that are associated with stepdown fixes, is expected, even after the side−step manoeuvre is initiated.
Approaches conducted to a side−step manoeuvre are limited to a Minimum Descent Altitude (MDA) regardless of the approach flown. Landing minimums for the adjacent runway will be based on non-precision approach criteria and are, therefore, higher than the precision minimums to the primary runway. Side-step minimums will be equivalent to, or higher than, the non-precision minimums for the approach conducted. Side-step minimums will also normally be lower than the published circling minimums.
A typical minima block for a approach which includes side-step criteria is depicted below.
Go-around from a Side-step Manoeuvre
If a Go Around is required, either during the approach or during the side-step manoeuvre, the published missed approach procedure for the approach flown is to be followed.
Although the risks associated with the side-step manoeuvre are not as significant as those inherent to a circling approach, the profile is not without risk. The most significant of these is landing on the wrong surface. This can happen in one of two ways:
- Failure to conduct the side-step - distraction or inattention leading to landing on the runway to which the approach was conducted rather than on the runway to which landing clearance was given
- Missidentification of the landing runway - side-step manoeuvres, in the past, have resulted in the aircraft landing on a taxiway situated between the two parallel runways
Both of these issues can be mitigated by a careful pre-study of the airport environment and an effective threat-based briefing.
Federal Aviation Administration (FAA)
International Civil Aviation Organisation (ICAO)
- ICAO Annex 6: Operation of Aircraft;
- ICAO Doc 8168: Procedures for Air Navigation Services - Aircraft Operations (PANS-OPS) Vol I - Flight Procedures);