Eyes on the Ground and in the Sky
In the high-stakes world of air traffic control, few environments require more split-second decisions and multi-channel awareness than the airport control tower. With a dynamic blend of visual tracking, spoken communication, vehicle movement, and evolving weather and runway conditions, tower controllers rely on more than technology alone to maintain safety. They rely on structured teamwork, distributed responsibilities, and something that can’t be automated: human judgment.
This article explores the nature of cognitive load and situational awareness in tower operations, highlighting how structured role separation helps manage both. We also take a critical look at the increasing push for surveillance in the name of safety, and whether it actually makes the tower safer.
Cognitive Load in Tower Control: More Than Just Planes
Cognitive load refers to the mental effort required to process information and make decisions. In a tower environment, this effort is divided across several dimensions:
- Visual scanning: tracking aircraft and vehicles by sight
- Auditory processing: monitoring multiple frequencies simultaneously
- Real-time decision-making: sequencing departures and arrivals, responding to requests
- Language management: handling non-native English speakers, unusual requests, or vehicle drivers using non-standard phraseology
Too much cognitive load, especially when it’s extraneous or unanticipated, can lead to missed information or delayed decisions. That’s why the tower team structure plays such a critical role.
Situational Awareness: Seeing, Understanding, Predicting
Situational awareness is the controller’s mental picture of the airfield and surrounding airspace. It’s typically broken down into three levels:
- Perception – Recognizing what is happening (e.g., aircraft lined up, a vehicle entering the runway)
- Comprehension – Understanding the significance of those events (e.g., conflict potential)
- Projection – Anticipating what will happen next (e.g., estimating separation, timing a takeoff)
In tower control, Situational awareness is built visually and aurally, but also socially, through constant coordination between controllers.
The Tower Team: Balancing Load and Frequency
The structure of a tower team helps manage both workload and frequency congestion:
- Executive Controller – Handles aircraft clearances and manages the runway. To reduce frequency congestion and focus cognitive resources, this role typically does not handle vehicles or non-standard communications.
- Assistant Controller – Coordinates with airport operations and speaks to ground vehicles and towed aircraft. This person often uses phone lines or a separate frequency, offloading the executive controller. Crucially, they act as a second pair of eyes and ears on the runway, enabling the four-eye principle.
- Ground/Delivery Controller – Issues en-route clearances and start-ups, managing pushbacks and ground taxi coordination. Only when aircraft are ready for taxi do they contact the executive.
This role separation avoids frequency overload and distributes decision-making. It ensures no one controller becomes mentally saturated, which is key to safety.
The Four-Eye Principle: Redundancy That Works!
When both the executive and assistant monitor vehicle movements and aircraft activity, it introduces a vital layer of redundancy. If the assistant hears or sees something the executive didn’t, like a vehicle mistakenly entering the runway, they can intervene immediately.
This principle isn’t just efficient, it’s essential. It allows controllers to focus without sacrificing awareness, and creates a safety net where silence isn’t mistaken for safety. For example, imagine the assistant catches a vehicle entering the runway without clearance, while the executive is fully focused on managing a late landing clearance for an arriving aircraft. Without that second pair of eyes, the intrusion might have gone unnoticed. The four-eye principle ensures that even when one controller is occupied, the operation remains safe.
Communication: Standard Where Possible, Flexible Where Necessary
While aircraft communication adheres to standard phraseology, vehicle drivers and maintenance crews don’t always follow those rules. That’s why having the assistant controller handle vehicle traffic is both a practical and cognitive safety strategy, it reduces noise on the main frequency and allows flexible communication where necessary.
Technology Can Help, If Designed for Humans
Tools like ground radar overlays, lighting systems, or well-designed electronic strips can reduce cognitive load, if they’re intuitive and don’t add complexity. Poorly designed interfaces, on the other hand, increase extraneous load and risk.
Recording and Surveillance: A Growing Concern
All communications between controllers and aircraft, vehicles, or other coordination units are already recorded. This includes:
- Radio frequencies
- Phone lines
- Intercom systems
These recordings are vital for investigations and accountability.
But now, ambient voice recording in the tower is being introduced. This means everything spoken in the control room, not just over frequency, is recorded. These developments are especially relevant as remote tower environments raise new questions about how situational awareness is built and monitored without direct visual oversight.
While intended to enhance safety investigations, many controllers question its value. Informal communication, such as a quick thumbs, up or silent glance, is often more efficient than speaking. Are we supposed to verbalize every action just to be recorded?
Even more intrusive: proposals for video recording inside the tower, following cockpit camera discussions after incidents like Germanwings or Air India.
Would cameras have revealed what happened in those cockpits? Possibly. But would they have prevented the events? Unlikely.
There’s a growing concern that surveillance isn’t about prevention, it’s about post-event blame.
Conclusion: Trust, Not Just Technology, Keeps the Runway Safe
Tower control is a delicate balance of situational awareness, cognitive clarity, and real-time decision-making.
Structured teamwork and smart communication channels are the first lines of safety, not just after-the-fact recordings. You can read more about the importance of human performance and teamwork in air traffic control in this related post.
Technology should support the controller, not monitor them. Safety isn’t just about knowing what went wrong, it’s about empowering the people who keep things from going wrong in the first place.