One in, One Out

You’re stuck on the ramp waiting to go, many planes ahead of you, arrivals holding and waiting on departures, departures waiting on arrivals. Whassupwidat?

maclawler

Thursday, November 21, 2024 at 08:00 AM ET

Verified

Key Takeaways:

The ability for airports to permit intermixed IFR arrivals and departures versus a "one in, one out" restriction primarily hinges on the availability of continuous radar services to the surface and the specific airspace classification (e.g., Class B/C airports have dedicated radar, while Class D/E/G often do not).
At airports without continuous radar (e.g., non-towered or some Class D), the "one in, one out" rule is crucial to ensure aircraft separation, as ATC cannot monitor aircraft visually or via radar during critical phases like departure or final approach, preventing potential conflicts.
Towered airports can achieve more flexible operations by providing visual separation, and advanced radar technologies (like WAAS/ADS-B) enable even en-route controllers to provide more precise guidance, allowing simultaneous approaches and departures at equipped Class D airports and significantly improving efficiency.

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Recently I received a good question about air traffic control procedures regarding approaches and departures. The question is: Why are some airports just one IFR arrival or departure at a time, while others permit a string of intermixed traffic? Well, lend me your ears (eyes) and let me tell you.

Why? Just Why?

The reason this is such an important question is the ability for ATC to permit a string of intermixed traffic obviously makes that airport much more efficient than those airports only permitting one at a time. Conversely, airports that don’t allow that string of intermixed traffic wind up with backlogs of aircraft trying to get in and out of them.