Last week I was interviewed alongside Kevin Hightower, Aviation Chief Technologist of Lockheed Martin, as part of a live webcast on the concept of Intelligent Approach.

Viewers from airlines, airports and ANSPs across the world tuned in to watch and ask questions about the tools that enable Intelligent Approach, including Time Based Separation (TBS) and Pairwise Separation; techniques that can offer major improvements for capacity constrained high performance airports.

There were more questions than we had time to answer and we were delighted to attract such wide spread interest.

I’ve decided to take the opportunity to answer some of those questions now and if you have yet to see the webcast then you can view the event on demand by completing the form at the end of this blog.

Is TBS still applicable during extreme weather with poor visibility, under ILS operation, say a CAT II?
TBS is operational in all weather conditions but under the most demanding Cat III conditions the spacing is driven more by the need to protect the ILS localiser beam than by wake vortex spacing. For example we typically go to 6 mile spacing in Cat III. That said we have developed the safety case for dynamic sensitive areas where we can use a landing clearance trigger line rather than a fixed Localiser Sensitive Area (LSA). This is based on the fact that not all aircraft have the same impact on the ILS localiser beam; so for example, with the new wide aperture localiser we can use a landing clearance trigger line for medium aircraft like A320/737 of 82m as opposed to the 137m which was the standard in the UK (other states use 150m). The Intelligent Approach tool knows the rules and hence can set up this variable spacing. This means that we can reduce gaps between arrivals dependent on the aircraft type and this can generate up to 30% reduction in delays due to low visibility. For Cat II conditions we typically apply standard TBS spacing.

Interestingly, at Heathrow the tower is 87m high so we also have another set of conditions where the airport is Cat I or better but the tower is in cloud so is no longer visual, under these conditions we switch to a minimum of 4nm spacing and the TBS tool automatically reflects this.

What impact can Intelligent Approach have to the airport on the terminal side?
Overall it is a benefit; the airport runs closer to schedule with less disruption which means that the stand plan is less interrupted and helps maintain departure punctuality. The statistics for Heathrow have improved overall since TBS went live and, significantly, we no longer see cancellations due to disruption from headwinds. When we move to pairwise, or for mixed mode runways, Intelligent Approach can actually increase both the tactical and scheduled landing capacity at the airport in which case the new schedule would need to be planned in the normal manner.

How does Intelligent Approach impact the traveling public? Less delays?
Yes that is exactly it. Less delay, a more repeatable and resilient service and much less chance of flight cancellations due to headwinds. We have also seen a noticeable saving in airborne holding since the system went live and when combined with our cross border XMAN (arrival manager), which streams aircraft from 350nm, the combination helps to save over 10,000 tonnes of fuel burn a year at Heathrow.

Can you explain in more detail how you down load wind speed from aircraft?
Yes, we have developed software called the Glideslope Wind Conditions Service, which uses the downlinked parameters from the aircraft which come via Mode S Radar to calculate the headwind component in real time. These parameters are part of the standard Mode S DAPs (Downlinked Aircraft Parameters) so there is no change required on the aircraft to enable this service to operate. We receive updates from every aircraft flying down the final approach every 4-6 seconds and use this to create a headwind component that the Intelligent Approach tool will use for the approach. As the wind conditions change the headwind component is continuously updated. The software includes error checking using a range of parameters and we trialled the algorithms over 12 months before TBS went live. We discovered high levels of accuracy that are far better than you could hope to get from ground-based measurements or met forecasts.

You may also be interested in a feature article about Intelligent Approach on our Discover channel.

Watch our webinar

Recorded live in July 2016, watch this recording on demand to find out more about how airports can maximise revenue by increasing runway throughput and by improving resilience. This webcast was presented by Kevin Hightower from Lockheed Martin and Andy Shand from NATS. Please fill in the form below for access.


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