A-CDM Procedure
The busier or larger an airport is, the more procedures there are to manage air traffic. Traffic management can involve reducing separation intervals between aircraft, using advanced equipment, or expanding airport facilities. However, the most common method is the A-CDM (Airport Collaborative Decision Making) system. This system assigns scheduled departure times (TOBT, TSAT, CTOT) for each airline, ensuring pushback and departures occur at designated times. If an aircraft fails to meet its pre-arranged departure time, it may face delays or penalties, which helps manage the heavy traffic efficiently through coordinated roles between airlines and air traffic control.
At major airports like Paris, New York, and Incheon, this procedure is widely implemented. Departure times (TOBT, etc.) are displayed on airport monitors, and airlines prepare their flights accordingly. If an aircraft fails to meet its scheduled departure time, its departure sequence may be pushed back.
From experience, adhering to the scheduled time at most airports ensures timely pushback and taxiing, even during peak hours. The “first come, first served” principle generally applies. However, exceptions do exist.
For example, Hong Kong Airport (in the past) occasionally prioritized Cathay Pacific, the national carrier, over other airlines, even if those other airlines were ready to depart earlier. Although this practice could cause brief delays (typically no more than 4–5 minutes), it didn’t feel particularly unfair. Many countries show preference for their national carriers, and this level of consideration is generally acceptable.
Enroute Separation – My Personal Experience and Observations
In Korea’s major airports, the phrase “enroute separation” occasionally feels like a convenient explanation when certain aircraft are held back during taxi operations. While it’s difficult to pinpoint clear evidence, there are moments when it feels as though national carriers are subtly given priority over foreign airlines under this reasoning.
For instance, even after adhering strictly to the TOBT and completing pushback on time, it’s not uncommon to see foreign carriers being instructed to hold on the taxiway for enroute separation. Curiously, during these holds, Korean carriers often taxi past and proceed to take off first.
Of course, prioritization of national carriers happens to some degree in many countries, and such practices are often within an acceptable range. However, in Korean airports, these instances sometimes feel a bit excessive, especially when they result in repeated delays for foreign carriers who adhered to their assigned departure slots.
If such holds are indeed unavoidable, it might be better to adjust TOBT schedules from the outset to allow for more efficient operations. This would at least reduce unnecessary taxi fuel consumption and the frustration that comes with prolonged holding.
The Case of Chinese Airspace and Enroute Separation
The term “enroute separation” also reminds me of specific routes over Chinese airspace. In certain regions of China, air traffic flow control measures often require extended separation intervals between aircraft. This can lead to delays at departure airports far from Chinese airspace if the flow of traffic cannot be accommodated at the expected time.
In these situations, the term “enroute separation” is used appropriately and aligns with airspace management protocols. However, even in such cases, pilots often receive limited information about the specific cause of the delay. The reasoning typically remains vague, leaving crews with no choice but to accept the instruction at face value.
At least in the Chinese airspace example, the delay stems from clear air traffic management constraints. However, in Korean airports, when “enroute separation” is cited, it sometimes feels less about actual enroute congestion and more about accommodating certain priorities—often favoring national carriers.
Of course, it’s impossible to conclusively determine intent, and air traffic control operates within established ICAO Doc 4444 guidelines. Nevertheless, repeated experiences of similar patterns create a lingering sense of unfairness among foreign carriers operating in Korean airports.
For a country with advanced aviation infrastructure and highly skilled air traffic controllers, greater transparency and consistency in applying enroute separation protocols would reinforce trust and fairness, ensuring that all carriers—domestic and foreign—feel they are being treated equitably.