The Tower Controller

The tower is the most visible to the outside world but within the ATC system is considered a second class citizen. Radar control is considered more difficult in general, but in my opinion tower controllers have the more responsible job, especially the local controller. Why? If there is a collision between two aircraft it is extremely rare for that to happen under radar control because radar controlled aircraft are separated by more than a mile at the closest, which provides a much needed safety buffer. The tower, of necessity runs traffic much closer. The airport may have intersecting runways which causes the local controller to fit the traffic together using very tight spacing. At night it is not uncommon for the controller to not be able to see traffic that he/she has lined up on the runway to await clearance for take-off. Only a few towers have radar for ground traffic.

Then there are scenarios like two aircraft approaching different intersecting runways, at times are a tie for the same piece of airport, but that may not be obvious until the aircraft are close in. That is not easy to judge. The local controller has to weigh so many variables, such as wind, runway condition, pilot ability, and even air-carrier company policy make every situation potentially different. The local controller closely watches these aircraft as they near the two runways and ifshedecides that the required separation it not going to exist, must abort the landing of one of the two airplanes.

But the controller is sometimes squeezed like a vice between "let them keep coming for now" and "go around" and if a go around is done too early, or unnecessarily it can cause a lot of potential problems. For example, the workload of various controllers goes up to accommodate an unexpected aircraft back into the airspace. The approach controller probably has to vector the aircraft back into the landing flow, and if there are lots of aircraft already set up and spaced for landing,shehas to find a "hole" for that aircraft. Also, a big jet that has been sent around is going to consume possible a few thousand dollars worth of jet fuel for the trip around the pattern. While this diversion is going on, has the controller remembered about all the other traffic and and agreements thatshehas made with other controllers, pilots, airport vehicles, etc. What if the controller allowed a vehicle to make a run down one of the runways, or approved an opposite direction approach, or that his supervisor wants to talk to him whenshegets off the position, or that his child is sick or wife is mad or...

The salient point is that the local controller has to constantly make decisions to insure a safe and expeditious flow of traffic under constantly changing conditions. Tower controllers play their 4-D chess game while every possible distraction is hurled at them. They have a super-heavy responsibility, and they merit our praise.

I have nothing but respect for them.

Back to the start of ATC Automation Part 1
Typical tower photo. The big boxes hanging from the ceiling are Tower Radar Displays, different from the radar displays in the dark radar room below. Tower displays must be visible in the presence of light. Notice the shades that are partially pulled down on the opposite windows. They are usually raised or lowered just enough to block out direct sun light, but hardly ever lowered completely until forced to. They prefer an unfiltered look out the window at their traffic.

Photo above by Martyn Davies under Creative Common License

10/23/2015
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Home ATC Automation Part 1 ATC Automation Part 2 ATC Automation Part 3 Scatter Scatter Part 4 Radar Handoff - part 5 The Tower Controller