Proximity Events

The FAA has reclassified separation standards between 2 airplanes by labeling situations where 90% of applicable separation standards are maintained as a proximity event. This accomplishes absolutely nothing when concerns about safety are addressed. Yes, an Air Traffic Controller will not be dragged through the mud and displayed with his/her Scarlet Letter attached when they can hold the line at 90%, but the simple fact remains that separation and safety were compromised.

Decades ago, the separation standard was debated and defined based upon equipment tolerances and the performance characteristics of the aircraft of the day. As aircraft got faster, and radar reliability remained the same, these numbers stood as the requirement of success and failure as a Controller. It was inevitable that someday, someone would figure out that 4 miles would work just as well as 5 miles did, and 2 as well as 3. The goal was, and always will be, no mid-airs.

The FAA has decided that a 3 mile separation standard could be reduced by 10%, to 2.7 miles without having to charge a Controller with an Operational Error (AKA OOPSIE). They will tell you that safety was never compromised. They will tell you that even violating that on approach to your favorite airport is nothing more than a compression error. What they won't tell the passenger or congress is that in a head on situation, at a 500 knot closure rate, they've decreased the margin of safety. It's slight but it is still decreased. 500 knots is roughly 8.3 miles a minute, it's over 0.125 miles a second. An eighth of a mile a second. In 8 seconds, you will lose a mile of separation. Think about that. It takes me 5 seconds to tell an aircraft what to do. On their best day, it takes a pilot .75 seconds to decipher the instruction, 2 seconds to take the corrective action and another 3 to 5 seconds for it to be visible as a means of providing separation. Those numbers are the best case scenario.

Someday, the person that advocated the big sky theory of separation will recant, and head on separation standards will be different than the "hell he can't catch them" standards of aircraft following one another. Until then, may all your near mid-air collisions be in-trail and not head on.