Page 23 - TNT Dec 2017

One Foggy Night
Managing low-visibility procedures like Santa.
Once upon a Christmas Eve flurry, RVR’s were squat; reporting six, four and blurry. “Our Christmas hustle must go on without pause;
we can’t wait for the weather,” exclaimed Mrs. Claus. Santa’s retort, was precise and quite short: “I work like a dog, when there’s snow or thick fog. Any bright lights, Christmas trees or red nose, will diffuse in the snow; it’s best I don’t go.”
But the elves had worked hard to empty the shelves, all eight reindeer well fed, were attached to the sled. The children had been good, this was well understood; everyone knew, what Santa simply must do. But the TAF we all know, predicted more heavy snow; his all-nighter flight, would be no delight. With VOR and red nose, though high- tech for a sleigh, without an ILS, there was simply no way.
Not his flawless approach, nor that glowing red snout, helped Santa to land; or to even break out. The missed and divert showed Santa’s pilot skills: dodging chimneys at first, then hill after hill.
Well, I’m sure Santa hated to disappoint all of the children Christmas morning, and he likely got an earful from Mrs. Claus when he called from his diversion hotel in Cabo...I’m just saying. But the mins are the mins, and without the right equipment on the ground and in the air, as well as proper training and proficiency, RVR’s of six, four and blurry are a show-stopper. Especially for eight flying reindeer and a sleigh, with or without a glowing red nose.
In 1929, Jimmy Doolittle became the first pilot to land an aircraft solely by reference to instruments. Since then, we’ve made giant strides in “low visibility procedures,” thereby minimizing the times we go missed or divert due to weather. It began with developing aircraft and ground systems, hardware and procedures, then qualification training and practice in order to fly non- precision approaches in the clouds. Eventually, inflight and ground systems were improved to the point we can now takeoff and land with visibilities measured in just a few hundred feet. Along this journey we found that once we land following a low-visibility approach, or try to leave after refueling, it could be difficult or impossible to find our way. Additional systems and procedures had to be developed to get us from the ramp or gate to the departure runway, or to our parking spot after landing.
Transmissometer
The primary ground equipment used in establishing which low-visibility procedures (LPV’s) are in effect is the transmissometer. Transmissometers are used to measure the extinction coefficient of the atmosphere and to determine visual range. They operate by sending a narrow, collimated beam of energy, usually a laser, through the propagation medium. In Santa’s case, snow and fog were the offending “propagation medium.” The measurements are taken at either one, two, three
December 2017
TWIN & TURBINE • 21
From the Flight Deck
by Kevin R. Dingman