Pilots must communicate with air traffic control (ATC) controllers to maintain a safe and efficient air traffic system for safe flights [1]. The International Civil Aviation Organization (ICAO) has recommended threat and error management (TEM) to pilots and air traffic controllers to enhance margins of safety through human factors [2]. As an airline, service providers must strive to collect and analyze the safety performance and identify hazards to manage safety risks [3]. Line operations safety audit (LOSA) monitors daily flight operations and collects data through observations of the flight crew in the actual cockpit [4].

The airlines and aviation organizations may collect data to identify the threats and errors of pilots while managing safety through LOSA as part of safety management system (SMS) according to Doc 9859 [5]. The data from the cockpit observation of ATC threats can be utilized for the safety change process to reduce human error and improve standard operating procedures and training.

The management of safety and quality assurance departments can prioritize and focus on better handling ATC, with identified ATC threats to pilots through LOSA data, as advised by ICAO under SMS Manual Doc 9859.

This paper is to provide information on the prevalence and types of frequent ATC threats to domestic pilots during normal flights by utilizing LOSA data conducted by airlines to prevent aircraft accidents and understand ATC threats, so the airlines may use them as a reference for pilot training and safety management in order to reduce pilot errors and prevent accidents caused by ATC errors.

1. ATC threats

1) Definitions of threats

The definition of a threat is an event or error that occurs without the influence of the pilot, which increases the operational complexity of the flight and requires the pilot’s attention and management to maintain safety margins [6]. ATC threats may be known before the threat is encountered. Most ATC threats are unexpected, except in some cases where they can be anticipated.

The TEM model is shown in Fig. 1 which shows that pilots must manage threats, errors, and undesirable aircraft states to maintain safety margins on a daily basis [7].

For airlines to operate safely, they must effectively perform TEM and implement LOSA to know and understand the types of real threats and errors that exist in the cockpit during normal flight.

2) Data collection on ATC threats through LOSA observations

LOSA observations of the cockpits of two domestic airlines identified the ATC threats present to cockpit crews during normal operations.

Among the threats collected during normal operations through LOSA observations in the cockpits of two domestic airlines in 2011 and 2018, ATC threat-related data was analyzed to identify the ATC threats existing to the cockpit crew.

The LOSA data presented in this study was obtained from a total of 415 observations made by 41 observers at approximately 64 airports at home and abroad.

3) ATC threats from LOSA observation LOSA observation data result on ATC threat

The data from two domestic airlines that implemented LOSA had 60% of their flights with an ATC threat. Table 1 shows the results of ATC threats through analysis of LOSA observation data.

The most frequent ATC threats to pilots are English & communication quality such as difficulty understanding controller accents or language, ATC controller errors such as wrong callsign, wrong clearance, wrong frequency, poor radio reception, similar callsign, and nonstandard ATC controller phraseology.

The second most frequent ATC threats are difficult clearance as difficult level change clearance, three or more clearances in one call, difficult level change and speed clearance at the same time, difficult speed clearance, and difficult to meet clearances.

The third most frequent ATC threats are runway changes as late runway change just before pushback or after pushback, late runway change below 1,000 feet, late runway change below 10,000 feet for approach, and multiple runway changes. The fourth most frequent ATC threats are regarding standard instrument departure change and unexpected holds. The last frequent ATC threat is ATC radio congestion.

Table 2 shows the data of ATC threats by phase of the flight through the analysis of LOSA observation.

The most ATC threats occurred during the descend, approach & land phase with 51% of ATC threats occurring during this phase of the flight. The second most ATC threats occurred preflight and taxi phase even before takeoff with 22%. The third most ATC threats occurred takeoff and climb phase with 16%.

The ATC threat data in Table 1 and 2 show that pilots must be trained in this area. It is best to conduct flight training through an aircraft, but in reality, it is difficult due to the high cost, and there are limits to abnormal training. Receiving training in these situations through simulator training at a ground school is the most effective training method that is closest to reality. By applying the results from LOSA in Table 1 and 2 to scenarios, evidence-based training can be conducted.

4) The study on ATC communication by ICAO

ICAO and the International Civil Aviation English Association (ICAEA) held a webinar on ATC communications based on the results of the ICAO language proficiency survey in October 2021. About 74% of pilots answered that lack of language and communication skills as the main cause of ineffective communication, and about 74% of pilots said the weakest communication skills are Pronunciation or accent [8].

ICAO’s findings show that pilots are working in a communication environment where language and communication skills are weak. LOSA data indicates that the biggest ATC threat was difficulty understanding the controller’s accent or language as shown in Table 1, showing that pilots were working in environments where ATC communication was difficult and lacked communication skills.

In this study, ATC threats to pilots are analyzed in LOSA observations as follows. First, the prevalence of ATC threats shows that there are six aircraft with at least one ATC-related threat in 10 flights. Second, the most frequent ATC threats to pilots are difficulty understanding controller accents or language, ATC English and communications quality, difficult ATC clearance, and runway changes. Third, most ATC threats have occurred in the descent, approach, and landing phases during flight.

The identified ATC threats by LOSA need to be improved. The investigation by ICAO and ICAEA confirms that pilots are working in communication environments with weak language and communication skills, as LOSA data points out. For continuous safety improvement, airlines can understand the threats and errors that exist in their day-to-day operations of LOSA to proactively manage human errors through effective SMS from data collected within airlines [9]. ATC threats are common to pilots of daily airline operations. The most frequent ATC threats have been found to have difficulty understanding controller accents or language and communication quality. Pilots face ATC threats that make it difficult to meet clearance by ATC and runway changes in routine ATC communications, which need to be improved.

It is proposed two suggestions in this study. First, it is needed to improve ATC threat management by conducting pilot training for flight control and workload management in the event of unexpected runway changes, especially by challenging ATC clearance during simulator training. Second, it is suggested that research materials and manuals on ATC be provided to describe the characteristics of ATC controllers in airports and routes so that pilots are anticipated of the defensive flight concept of TEM and anticipate the ATC communication prior to encountering ATC threats.

No potential conflict of interest relevant to this article was reported.

None.

This article has revised and supplemented the contents of the 23rd Korea-Japan Joint Symposium of Human Factors and Ergonomics in 2021.