To 4D or Not to 4D?

What path will determine the future of Air Traffic Control?

Currently Air Navigation Service Providers (ANSPs) pretty much universally determine (excluding regulators), based on ICAO principles (or framework), the standards and the manner in which Air Traffic is managed.

The ICAO framework is under constant review; with a view for a long term plan. Europe, Asia, Africa, Australia, USA, Canada, South America all have various national and international plans; but is there a true global vision? Well is that not the role of ICAO? Are they doing their jobs? Is ICAO determining a future plan, if so how? Who has a seat at the right tables in the decision making processes?

Boeing and Airbus have become the dominant Civil Aircraft manufacturers, with a few ‘specialists’ doing their bit; but not in the league of the big boys. Boeing and Airbus have commenced work on Air Traffic Management, Boeings programme is now defunct or about to be by all reports. The inference is that the End User (the airlines) like the products they buy and wants the airlines to develop the best methods for flying them economically (and most profitably); to do this, the effect of ATM must be known, how do you know it? You own it.

Who is the key player in the future ATM, IATA?

4D trajectories rely upon increased accuracy and different intervention methods by the ATM systems. 4D essentially is the tracking and projection in space along the lines of latitude, longitude, altitude and time. That is that the 4D trajectory will always be know, always be accurate, always be compatible with flight elements and always be adaptable.

The 4D dreamers will have you believe that there will be essentially no role for Air Traffic Controllers in the post 4D system introduction. So what is the time line? From the information passing via this tech head, it’s beyond 2025; but reading some papers you will see full (limited to a specific area) implementation by 2015.

Aircraft rolling off the factory floors today don’t have the appropriate avionics to do 4D; some of the elements, but not everything; particularly up-linking integrity and flight accuracy. So what of 2025 implementation? How many years is equipment being purchased today going to last? One suspects it will be well beyond 2025; thus there can’t be full implementation by 2025. Let’s not mention GA, or military ops; UAVs and the like. Did someone say weather? Did someone say non normal ops?

The ‘technology’ will need to be 100% accurate, 100% variable, 100% reliable and 100% unbelievable. Is this the realm of “pie in the sky BS” or really going to become a reality.

Recent trials have scene Constant Descent Approaches and CPDLC (Data link) routing uploads (makes for great PR for airlines and ANSPs); with the time elements, the crucial crux of 4D, described as a roaring success because the aircraft involved were flown within 95% target range.

Flights are contained within 2 ‘bubbles’, the first nominally being called a ‘freedom bubble’ and the second a ‘safety bubble’. Essentially no other Hazard shall enter the Freedom Bubble, cause that means near miss; it's a bubble to allow changes to heading, potentially altitude and speed without the need to calculate a whole new 4D trajectory; but at all times must stay inside the freedom bubble. The Safety Bubble will need to take account of things such as wake turbulence displacement; navigation accuracy, safety margins etc.

From what I can guesstimate that need to remove ATCs and ANSPs is to increase safety and capacity; great goals. But what really reduces capacity; often it is nothing to do with ATCs; it’s more to do with infrastructure; such as surveillance availability or runway and airport capacity; this will not be dramatically increased by airborne automated systems; although we do concede there is great potential to have “finals spacing” regulated and improved; this may save 2 or three minutes across the hour for a couple of aeroplanes.

But whilst in the real world, the likelihood of an automated system actually providing increased capacity is extremely limited as all the variables will be defaulted to minimum safety in all circumstances.

ACAS (such as TCAS) enhancements allowing for pilot to pilot collision resolution and in trail climb/descent procedures etc. will enable increased airborne capacity far more readily than the concepts surrounding 4D; but to what end? Airborne capacity is reduced by two factors, workload and technology. These two things go hand in hand; improved technology means less workload.

As an example one $5M radar site strategically placed in a current non surveillance area could reduce sector numbers (by about 3) and thus controller numbers (by about 12); increase capacity, increase safety, increase efficiency and reduce industry charges. Investment in the new (like that 90 year old radar thingymajig) will pay off in spades; by why won’t they listen? One off investment of a trivial amount of money would be recovered in 3 years worth of ATC wages alone; forgetting the economic benefits directly into the airlines pockets.

The investments in the future is ‘gearing’ towards 4D, User Preferred Trajectories, flex tracks, automation, ADS-B (in and out), CPDLC.

But my real question after all that is should existing ATM systems be enhanced with more modern and known (trusted) technology or should we be jumping ship into a new direction with gusto; knowing one day it will leave port we just don’t know when.