1/28/11

Error Of Omission

People, sometimes even us controllers, make bad decisions in life. Oh, they appear to be fine at the time; wise and considered ~ decisions that will bring us to a desired outcome. Sometimes though, we don't think things through or cogitate the possibly negative consequences. We don't do an adequate risk assessment. The result can not only be a bad decision, but possibly the last decision we ever get to make. And sometimes the outcome of a bad decision is exacerbated when important data is discounted or omitted during the decision-making process. That's where we came in on one very inclement Summer day.

Big Time's surveillance radar made its ceaseless sweep around the airspace and each turn of the antenna painted a changing panorama of storm cells and circuitous traffic patterns. Although arrivals were crowding into holding patterns and receiving lengthy EFC delays; approach controllers somehow managed to weave a few at a time around the shifting weather and on toward a waiting ILS. From my position in the tower, the airport was a dreary looking place; partly obscured by steady rainfall and occasional fog. Airplanes were landing though ~ some even reporting decent conditions on final. This didn't mollify our growing concern over the darkening skies just north of the field.

Down in the TRACON, frequencies were squealing with transmissions from pilots who refused to accept assigned headings. Departures were deviating into adjacent ARTCC sectors while arrivals wandered into the departure flow. Pointouts, both inter and intrafacility, were frequent and frantic. Many were done by Supervisors who would dash across the radar room from one sector to another; point at a particular target on the controller's display and say something like: "Watch this guy - he's turning left!" The room was rife with the smell of sweat and cigarette smoke.

High above a small rural town some miles from the city, the pilot in command of one passenger jet in a holding pattern listened to Big Time's ATIS broadcast. He'd been listening to other flights in the pattern. Some were now on their way into the airport while others were being cleared to an alternate destination. It sounded like rough going no matter which way you were headed. He tuned into the tower frequency and listened to a few pilot reports about conditions on final. When his turn finally came to leave holding, he decided to go for it. As he was vectored out of the pattern, other flight crews in the hold were probably happy to sit tight for a while longer ~ hoping conditions would improve.

Unfortunately, conditions were not improving. In fact, they seemed to be worsening. Landing airplanes came into view about a mile out, crabbing a few degrees left to compensate for a gusty, quartering crosswind. Then they'd kick it straight toward the runway, touch down and quickly fade into the mist blown up by their reverse thrusters. Local Controllers would ask; "Say flight conditions on final." The reports remained relatively benign ~ not as bad as it looked ~ braking action good. "Thanks Cap'n. Contact ground point seven." But a vile looking veil of weather was looming to the north and closing in on our only usable ILS.

Wind-driven rain slashed incessantly at the tower windows. Neophyte that I was, I stood at the Ground Control position, watching the approaching darkness nervously and shifting my weight from one foot to the other. Everyone in the cab was talking about the lightning and watching the wind direction indicators; now beginning to twitch erratically back and forth in a 45 degree arc. I saw gusts approach 30 knots and wondered just how wet I was going to get on my way to the parking lot at shift change.

Glancing at the BRITE display, I saw another airliner turn to intercept the final. Lightning flashed within five miles of the field and the rain intensified. Our high intensity runway lights glared in the distance but, from where we stood, there was only a diffuse glow. Somebody called over the outer marker. I remember looking north and imagining the conversation in that cockpit! I could barely see the airfield boundary through the rain but, somewhere out there, a 707 had just touched down. As it rolled onto the second high-speed turn-off, the pilot asked for progressive taxi instructions to a remote cargo ramp.

The next time I looked at the BRITE display, the airplane making an approach was about three miles out. Looking toward the final was like staring into a railroad tunnel. There was nothing to see but blackness.

Just then, someone came up the steps to relieve the tower Supervisor. Comments were exchanged about how hostile the weather looked and how unwieldy the radar operation had been so far. I heard the local controller give another wind check to the guy on final so I looked off into the murk ~ expecting to see some landing lights. Nothing. No reply from the crew either.

A few seconds later, I saw it. First some lights; blurred by the intense rainfall. Then the whole airplane came into view. It was well right of the runway centerline and, somehow, didn't appear to be flying anymore. Still airborne, it looked like it was simply hurtling along on a trajectory established when its wings lost their lift. Nose high and tilted to the right, it fell quickly toward the airport.

Frozen, like insects in amber, everyone in the cab watched in silence. It was the silence of knowing what was to come next. Someone reached for the crash phone.

The plane hit ground with a thud that we could feel a mile away. From there, it slid along the wet grass next to the runway; skipping across a couple of connecting taxiways before skidding to a stop near the main terminal ramp. Along the way, its fuselage broke open. There was no fire and, moments after coming to rest, people began climbing out of the wreck through a gaping crack just behind the wings. Some were clutching briefcases. It was surreal.

The pilot had decided to continue with an approach that would take his airplane into some very sinister looking weather. He'd made his initial assessment before leaving the holding pattern and had decided it was worth coming down for a look. Turning onto the final, the soundness of his decision might have been debatable. However, other flights had gone through ahead of him and known conditions didn't prohibit a shot at the approach. But there were known conditions he was not aware of; conditions unintentionally omitted during his critical decision-making moments.

Were ATC's hands clean on this one? We all thought so. Except for the new kid on Ground Control, the tower crew was comprised of some of Big Time's best and the Supervisor was a savvy veteran who'd seen all of this before. Everything seemed to be clicking and, throughout Mother Nature's assault, we managed to move a lot of traffic in and out. But the tapes tell all.

Sometime shortly after that 707 landed, the touchdown RVR had dipped below minimums for the approach. No one in the tower caught it in time. We were all too busy watching the weather move in. Wind checks, braking action reports and other flight conditions were transmitted while this plane made its approach but we missed that critical change in the visibility. It was an error of omission ~ one that would change a lot of lives forever.

Rain was still falling heavily at shift change. Our crew walked out to the parking lot in small groups; everyone soaked, muttering and shaking their heads in disbelief.

© NLA Factor, 2011

2 comments:

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