A little bit about NextGen Air Traffic Control Part 1

I’ve had a few people ask me about NextGen air traffic control over the past couple of months wanting to know what it is and if it really is the silver bullet to current problems so I thought I would take a few minutes to give a cursory description of what it is and why airlines want it.  This is part 1 and we’ll have part 2 tomorrow.

 

The FAA has tried to find and implement a new system of air traffic control for 20 to 30 years now.  Airways were crowded in the 1960’s and 1970’s and all parties knew it was time to find better methods of controlling aircraft.  Contrary to what is often read in general news media, the current system is not 1950’s technology.  The basic system of controlling aircraft was introduced in the 1950’s, the technology has evolved and been improved a number of times over the past several decades.  That said, the issue with the technology is that in our modern microchip world, our current ATC technology is still kind of rooted in the mainframe era.  You can go only so far with a system and the technology that supports it before you need to transition.

 

NextGen really is two things.  First, it’s a re-envisioning of how we control aircraft.  In other words, we’re talking about re-inventing air traffic control and we’re able to do that because of newer, more modern technologies.  Before going farther, you have to imagine first that any system we use is not similar to a highway system because not only are we concerned about direction and speed, we have different altitudes to use too.  It’s more like layer upon layer of highway systems. 

 

The old system (and by system, I mean methodologies for controlling air traffic) was conceived in an era where our knowledge and technology allowed us to navigate with a fair degree of precision for that era but which still required a fairly large dose of margin of error to make it safe.  Under the old system, have a system of “points” that pilots can navigate to and upon reaching those points, they then navigate to the next point they need to go to.  When they create a flight plan, it is a plan that states which points they’ll fly to (within the rules of planning) and at what altitudes and speeds they’ll do it at.  It is a kind of multi-dimensional connect the dots plan.   Ever see the actual flight path of your aircraft and wonder why it looks a bit convoluted and twisted?  It’s because pilots are flying along airways from point to point rather than from departure to destination direct.

 

Let’s say a pilot for an airline wanted to fly from Chicago to Los Angeles.  Currently, the pilot cannot simply take off, flight at an altitude of his choice and fly directly from Chicago to Los Angeles.  Instead, he takes off, flies to a point that is on or close to a routing that leads him in the *direction* of Los Angeles and he continues to fly from point to point to get to Los Angeles.  As he gets closer, he flies with more precision to the airport by navigating to points that lead him to Los Angeles.   Flying to these points is essentially done by “homing in” on radio broadcasts from beacons at these points and through direction from air traffic controllers who are “tracking” his flight via radar. 

 

Neither the radio nor the radar paint a very precise picture.  There are many seconds delay in the radar that paints the picture of the aircraft and where it has been and where it is going.  If there is, say, a  15 second delay, that amounts to a lot of error.  It doesn’t sound like a lot but consider that these aircraft are traveling at 530mph.  That aircraft is traveling 0.15 miles / second and in 15 seconds, it has traveled nearly 2.5 miles.  In 30 seconds, it has traveled nearly 5 miles.  In just one minute, it has gone 10 miles.  This explains why we currently require so many miles of separation between aircraft in the air.  When you hear about aircraft being required to stay 5 miles away from each other on the horizontal, it probably sounds excessive.  When you consider that an error in knowing where you are that last just 30 seconds, you may well lose all of that separation and suddenly run into another aircraft. 

 

We’ve developed some systems over time that mitigate these risks such as TCAS (pronounced TEE-CASS) which stands for Traffic Collision Avoidance System.  This allows two (or more) aircraft to announce where they are to other aircraft and to decide if these two aircraft are on a collision course.  If they are, one system tells its pilot to “dive” and one tells the other to “climb”.   The problem is, aircraft have accurately know where they are for this to work.

 

For the most part, they do.  Airliners use a complicated set of gyroscopic inertial navigation machines.  These sophisticated machines sense movement direction and speed and if they know where they were before they started moving, then they can tell where they are as they travel.  Again, the problem is that the precision of these systems is measured in miles rather than feet. 

 

Next up, what we can do now.

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