About types of runway incursions, causes, and prevention you can read here:
1. Important Structures and Features at Towered Airports
First of all, what exactly is a runway incursion? A runway incursion is any presence of an aeroplane, a vehicle, or even a person, who has no ATC clearance to be on that runway at that point in time. Runways are defined as protected airport surfaces from which airliners take off or land on at high speed.
In this article, we will occupy ourselves with towered airports, which handle civil aviation. As we have seen in the case of Los Angeles International Airport, LAX, where a devastating accident happend on the runway in 1991, such airports can be extremely busy.
1.1. Apron, Taxiways, Runways, and the Traffic
Runways can run in parallel or cross one another. They are also crossed and linked to the apron (were the aircraft are parked and serviced) by a number of taxiways. On all of these airport surfaces, there can be dense traffic.
Not only aeroplanes of all sizes use all of these areas, but also all kinds of vehicles, such as bowsers and passenger busses, operate on the apron and taxiways. Pushback tractors do not only push back the planes when they are ready to take off, but also tow them along the airport as needed.
In the next two subchapters, we will highlight in what way airport signage and markings, lighting at night, as well as air traffic control, ATC, facilitate the smooth flow of all traffic.
1.2. Airport Signage, Markings and Lighting
All taxiways, crossings, and the runways with their intersections and entrances are clearly indicated by internationally standardised signs which are mounted next to them. The signs are illuminated in darkness. The identifiers of a runway are also painted onto the tarmac at the runway threshold.
On the tarmac, there are different sorts of crucial markings, which, for instance, clearly indicate runway crossings. Various types of lights, such as the runway centrelights, illuminate the taxiways and runways at night. Other sets of lights guide the pilots on their final approach. All types of signage, markings, and lighting are explained in the Pilot´s Handbook of Aeronautical Knowledge (1).
1 ) US Department of Transportation, Federal Aviation Administration, Flight Standards Service (2023): Pilot´s Handbook of Aeronautical Knowledge. Chapter 14, pages 14-5-14-22.
1.3. Air Traffic Control
At larger airports, air traffic control is split into sections, which work closely together. Briefly, there is the aerodrome control service, which guides all planes and vehicles along the airport surfaces and the approach control service, which separates the aircraft during climb, descend, and approach.
No aircraft or vehicle is allowed to move on the airport surface without clearance from ATC. Moving without ATC clearance can result in a runway incursion.
2. Types of Runway Incursions
A runway incursion in itself does not mean that it results in an accident. However, a collision can have severe consequences if at least one aicraft involved is travelling at high speed.
2.1. The Most Common Types of Runway Incursions
In this subchapter, we will look at the different types of runway incursions. As we have just seen, moving onto a runway without clearance from ATC is classified as one type of such incursions. The most common ones are summarised in the figure below.

2.2. A Particular Type of Runway Incursion: Runway Confusion
When a flight crew enters the wrong runway for its take-off or lands on a runway for which it has not been cleared, this is called a runway confusion.
A tragic example is the accident of Comair flight 1-91 at Lexington Airport, Kentucky, USA on 27 August 2006.
The captain and his first officer were cleared to take off from runway 22. Instead, they taxied onto runway 26, which is shorter. They realised their mistake too late and crashed after a failed attempt to take off. The first officer was the only survivor and suffered severe injuries.
The following factors contributed to this accident:
- the cockpit crew engaged in casual conversation as they were taxiing towards the runway; hence, they violated the sterile cockpit rule
- the two pilots did not finish their checklist for their taxiing; thus, they overlooked that they should have communicated any crossings actively (in that case the crossing of runway 26)
- ultimately, they lost their situational awareness and noticed only during their take-off roll that the runway was not illuminated
When they reached the end of the runway, they could not abandon their take-off any more. They had to lift off and crashed.
3. Examples of Errors That Lead to Runway Incursions
Anyone who is involved in airport operations can make an error, regardless his or her profession (air traffic controller, pilot, vehicle driver), rank, or experience.
Air Traffic Controllers
An air traffic controller, ATCO, may issue clearances that infringe the separation minima. This means that there is not enough space between two aircraft which depart from or land on the same runway. Following that, the part of the runway available to the respective aircraft might be too short to carry out the intended operation safely.
Pilots
Pilots may become disoriented at a large airport which is unfamiliar to them. Instead of stopping and asking ATC for progressive taxi instructions, they might continue their taxiing and, along the way, enter an active runway unintentionally.
In addition, it is a common mistake that pilots confirm an ATC instruction, but fail to follow it correctly. For instance, they may cross an intersection instead of holding short as they have been requested to do.
Vehicle Drivers
It is of utmost importance that all vehicle drivers are properly trained and know the meaning of all signs, markings, and standard phraseology when communicating with ATC. If they misinterpret a sign or an ATC clearance, they might cross an active runway by mistake.
4. Potential Contributing Factors
When the errors, which we have discussed in subchapter 3, are investigated, the contributing factors that lie behind them are brought to light. Below, we will look at a selection of such factors.
4.1. Examples of CRM-Related Factors
A High Workload
After landing, the pilots have to configure their plane according to the after landing checks. In addition to that, they have to orientate themselves quickly and comprehend where on the airport they are and how they reach their parking position from there.
At busy airports, ATC might instruct them to hold short of intersections several times. The ATCOs themselves may also have a high workload when handling several planes in a short amount of time. Therefore, they usually do not have the time to monitor whether a cockpit crew follows their instructions correctly, which would provide an extra safety net.
Distractions
A distraction can be caused by a myriad of circumstances. For instance, pilots could be distracted by a warning light which suddenly flashes in their cockpit. Subsequently, they might miss an important sign on the ground outside.
4.2. The Airport Layout
The airport layout plays a crucial role. As we have already seen, runways can run in parallel or cross one another. Normally, all runways are used for take-offs and/or landings simultaneously, regardless their layout. Taxiways can lead towards them or cross them at various angles. Any confusing signage and the close proximity of some runway thresholds enhance the likelihood of mistakes.
4.3. Weather Conditions and Poor Visibility
Heavy rain and snowfall, as well as icy runways, or strong windgusts increase the pilots´ workload. They might also distract them when they are concentrating on finding their way at a huge airport with a complex layout.
Poor visibility caused, for instance, by fog, impairs the ATCOs´ work, as well. As they cannot see the aircraft, they must rely on the ground radar in order to cross-check their current positions on the airport surface.
By now, we have highlighted many a factor which increases the risk of runway incursions and can have devastating consequences. In the subchapters 5 and 6, we will explore what every professional at an airport can do to minimise this risk. We will also discuss valuable technical aids in subchapter 7 and the so-called perimeter taxiways in subchapter 8.
5. Specific Knowledge and Skills Are Used at an Aerodrome
In this section, we will uncover some of the peculiarities of the pilots´, ATCOs´ and pushback tractor operators´ daily work routines.
5.1. Pilots Prepare for Their Take-offs and Landings Thoroughly
Tasks Before Take-off
In their briefing before pushback, the pilots prepare for the first phases of their flight which includes their route along the taxiways for which they use detailed maps of the airport. This preparation helps them to keep their situational awareness and to manage their workload during departure. The workload includes the completion of several checklists, configuring the aeroplane for take-off, and communication with ATC.
After Touch-Down, the Flight Is Not Over Yet
During approach, the pilots prepare for their landing, which is another busy phase of every flight. After their landing, they need to taxi according to ATC instructions safely in addition to other tasks. Pilots are advised to write down complex instructions and they are encouraged to communicate to ATC clearly if the cannot follow one of these.
5.2. At Many International Airports, ATCOs Operate the Runway Stop Bars
As opposed to the runway status lights, RWSL, which are fully automatic, the runway stop bars are operated by the ATCOs. Runway stop bars are red lights that sit in the tarmac at the intersections between taxiways and runways, as well as at the entrances to the runways. They are switched on in poor weather conditions with low visibility. Only when an ATCO has issued a clearance for an aircraft, which allows it to enter the runway, the air traffic controller switches off the red lights at the intrance to the runway or the respective intersection.
5.3. Driving a Pushback Tractor
Pushback tractor operators push back an airliner, which is the very first part of its journey. In addition, they move the aircraft along the airport surface, for instance, to tow them to a hangar for maintenance. They have to adhere to busy schedules and ensure safe operations at the same time.
This means that they not only need to know everything concerning the complex handling of their vehicle, but also how to move at an airport, which includes the following:
- communicating with ATC clearly and precisely
- being aware of the conditions, such as wet or icy surfaces
- moving constantly, but slowly and preparing for anything that could obstruct their planned path
- watching out carefully for all signs, crossings, etc.
- considering the wingspan of the aircraft in order not to graze another plane, which can have devastating consequences if this goes unnoticed
6. CRM Principles Help to Prevent Runway Incursions
Although technical aids play a decisive role in preventing runway incursions, the active use of CRM principles is still critical. No matter in what line of business we are, we should maintain our skills, not only because technical equipment may fail at any time.
In the following subchapters, we will look at a selection of important CRM principles and how they are used at airports to prevent runway incursions.
6.1. Situational Awareness
The situational awareness at airports includes spatial awareness (where are we ourselves and where are other planes and vehicles?), the awareness of time (when should what aircraft be where according to flightplans and schedules?), as well as awareness of all available information (what clearance has been given to whom, weather, any changes or technical difficulties).
6.2. Communication
In addition to their own communication with ATC, which requires standard phraseology, closed communication loops, and an excellent knowledge of English, pilots must also be aware of the communication other cockpit crews are having with ATC. This might provide them with important clues pertaining to occupied runways, etc. Inside the cockpit, the sterile cockpit rule applies.
6.3. Thorough Preparation
For every phase of their flight, pilots prepare carefully using checklists, but also other important sources of information such as the Automated Terminal Information Service, ATIS. Vital information about an airport, including the weather, is played on a loop on a local frequency. It is updated every hour or more often when needed. Using all their available information, pilots anticipate any difficulites which they might encounter during a take-off or landing and plan for eventualities.
6.4. Workload Management
The workload must be managed by pilots and ATCOs alike. This includes sharing the workload in the cockpit appropriately. All professionals can use phases with a lower workload to prepare for those, in which they expect more work and prepare for this. As you can easily see, workload management is intertwined with the topics "preparation", "anticipating", and "planning", which we have just mentioned.
6.5. Other Important CRM Principles
- excellent teamwork, including a common goal
- a shared mental model of a given situation, such as blocked runways and its implications
- assertiveness in the teamwork; speak ups should be addressed
7. Technical Epuipment on the Ground and in the Planes
The RWSLs are triggered by planes that are going to use the respective runway for take-off or landing. The runway stop bars are independent from any communication with an airliner. The surface radar shows the ATCOs what aircraft is where on the airport surface. Two more helpful technical systems are installed in aircraft, the runway awareness and advisory system (RAAS) and the traffic alert and collision avoidance system (TCAS).
Traffic Alert and Collision Avoidance System, TCAS
TCAS works in the air and on the ground. It alerts the crew whenever another plane, which is also fitted with TCAS, comes too close. At the same time, it provides a solution in both airliners in order to avoid a collision.
Runway Awareness and Advisory System, RAAS
RAAS is linked to GPS and certain aircraft sensors. It provides the crew with so-called routine advisories and non-routine advisories. The former announce, for example, the runway ahead of the pilots and how many metres they have left on it. The latter alerts the crew if they are on the wrong runway, for instance.
8. Perimeter Taxiways at Dallas/Fort Worth International Airport
As we have seen in subchapter 4.2., the geometry of an airport can influence the likelihood of runway incursions. After intense reseach, which was conducted jointly by DFW International Airport, NASA, and the FAA, perimeter taxiways were being built starting in October 2007.
These taxiways are located at the ends of each of the seven active runways at DFW, which means that pilots can now taxi around the runways instead of crossing them when they enter or exit them. This, in turn, reduces the number of potentially dangerous runway crossings and the related communication between the pilots and ATC. Therefore, the workload is reduced, which helps to concentrate on safety-critical tasks.
Congratulations! You have worked your entire way through a long and comprehensive article. Well done!
If you like, take a few moments to recapitulate, what you have read in this article. Where at your own workplace do you detect hazards or circumstances that enhance the risk for errors? What can you do about it?
9. Next Month: Scene Safety in Prehospital Emergency Medicine
What does scene safety entail when an ambulance and a doctor´s car respond to a call? Other services, such as the police and firefighters, are also involved in some cases. In the next article, we will explore various types of scenes and the potential hazards for which every team member should prepare. How does CRM help to mitigate the risks?
Author: Eva-Maria Schottdorf
Date: May 31st, 2024
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