By Fred Gibbs

Just to be clear, the opinions and statements made within my articles are strictly mine and may not necessarily reflect any policy or position of the Arizona Pilots Association.

Please, keep safety on your mind at all times, and remember, “Safety is no accident.”  Preflight briefings, which include weather briefings, are essential to that safety mantra. You have heard me say many times that the short, easy flight from the valley up to northern Arizona, and particularly into Flag, can catch you by surprise. With winter approaching, the weather can be significantly different in that 100-mile, 45-minute flight. Winter conditions up here can be, um, challenging. Snow showers, snowstorms, snow covered runways, taxiways and ramps, lots of ice, especially black ice, on the taxiways and ramps as a result of daily heating and overnight freezing. Parking overnight? Well, very cold temperatures, potential frost and hard starting are all early morning issues and need to be carefully mitigated and/or planned for. Temperature swings of 40 plus degrees are almost normal all winter, ranging from 0 degrees overnight to 40 plus degrees when the sun comes up. So, if you plan to come up to Flagstaff, please, please check NOTAMs! Like I mentioned in last month’s article, the tower is currently suffering through a staffing shortage, that, often, during the day, closes tower operations for short durations (usually 30-45 or so minutes), turning us into a non-towered, non-radar, class G airspace operation. This requires you to pay very close attention to traffic pattern operations, for possible practice instrument approaches, helicopter operations and, of course, the commuter jet traffic. For those short periods of non-towered airport operations, extra special vigilance is required! More radio and self-announcements may be, and should be, required to keep everyone informed of where you are and what your intentions are, but good radio technique and phraseology is also required so as to NOT be confusing or tying up radio time for other aircraft.

Another tidbit – As mentioned last month, the Flagstaff area is a non-radar environment, especially below 9000 feet (for a variety of reasons not covered here), so position reporting is very important when checking in with the tower or when the tower is not in operation! We strongly recommend you contact the tower or broadcast your position at least 10 miles out with your position in reference to the airport, i.e., 10 miles SOUTH, and to include your altitude, i.e., at 9500 feet. For your edification, the tower does not need your altitude, but other aircraft coming to, or leaving from, Flagstaff will certainly appreciate it. If you don’t give the tower all that information on your initial call, it most likely will necessitate ANOTHER radio call from the tower to get that information, further tying up the frequency. On that initial call, a precise position report can alleviate a lot of extraneous radio chatter and significantly improve services at the airport. An initial call to the tower saying “N12345 is with you on the visual” will generate at least two more radio calls from the tower that you will need to respond to, certainly tying up the frequency much longer than one precise initial call!

Also, with the FAA now putting very high emphasis on runway incursions because of the many incursions and near misses that have occurred over the past couple of months, you may see more delayed departure (takeoff) clearances. Towers will be very closely watching the spacing issue for arrivals, and here at Flag, for example, once the commuter jet reports their 5-mile final position report, you will most likely have to wait until they land, roll to the end of the runway, and are clear of the runway before getting your ”Cleared for takeoff” clearance. That is just the way it is…. And you will NEVER get a “Taxi into position and hold” or a “Line up and wait” clearance here at Flagstaff, ever!

On another subject, with winter coming, the airline operation will most likely involve de-icing every morning. The CRJ-700’s on the terminal ramp are occasionally pushed back onto the taxiway leading into the West Complex (hangar area) or across the taxiway onto the ramp area right next to the taxiway for their de-icing process. This does, on occasion, create a bottleneck on the taxiway leading into and out of the West Complex hangars and shades. Thusly, the following procedures are recommended –

If you are coming out of the West Complex, and just for clarity, you would be on the west taxiway, NOT Alpha 6. The west taxiway, ironically, just happens to align with Alpha 6 upon connecting to taxiway Alpha (See arrow #1). Alpha 6 is the connector between taxiway Alpha and the runway.

The recommended procedure coming out of the Runway Safety Action Team (RSAT) is to contact Ground early for taxi clearance, i.e., before reaching the blue gate or adjacent to the wash rack area (ARROW #2). If, upon landing, you are going into the West Complex, advise the tower early so they can plan on a runway exit strategy to avoid any conflict at the west taxiway, currently referred to as Alpha 6.

FYI, under the airport master plan there is a project envisioned to move the taxiway coming out of the West Complex. The proposal is to NOT intersect taxiway Alpha at Alpha 6, but to come across the ramp area to join taxiway Alpha between Alpha 6 and Alpha 7. The intent is to resolve both the taxiway alignment issue and the pushback/de-icing issue, but that is way down the road.

Let me introduce you to the newest air traffic concept under study right now. It is called The 4D Trajectory Based Ops Concept.

The 4D trajectory of an aircraft consists of the three spatial dimensions (latitude, longitude or radial/distance and altitude) and introduces time as the fourth dimension. Adding a CTA (Controlled Time of Arrival) or a time to a fix or position into the 3-dimensional world now becomes a relevant part of any flight or the planning of that flight, referred to as the Reference Business Trajectory (RBT). This means that any change in position or a timing error (CTA at a predescribed fix) is in fact a deviation from the flight plan, causing an error in the projected pre-planned RBT. This could/can cause a significant impact on all following traffic on the same flight path (trajectory), and could therefore require controller intervention. Currently, tactical interventions by air traffic controllers rarely take into account the effect on the trajectory as a whole, due to the relatively short look-ahead (20 minutes or so) time, for those aircraft within their own airspace. In basic terms, a 4D flight plan will need every center whose airspace is traversed by the 4D flight plan to concur prior to flight. This will require every center and TRACON’s computer system to be a player in the flight planning process.

The 4D trajectory concept is based on the integration of time for the entire length of the flight into the aircraft’s 3D trajectory. It aims to ensure flight on a practically unrestricted, optimum trajectory for as long as possible in concert with the aircraft being obliged to meet very accurate ETA’s (arrival times) over a designated point. This would require a very sophisticated and accurate Flight Management System on board the aircraft constantly computing position and recommending (or making) speed adjustments to hit the required fixes at a very specific window of time, perhaps within a minute or two, or even closer. This whole concept is certainly obtainable – just watch space shots, orbit intercepts, space station hookups, lunar landings, etc, but one at a time obviously won’t work for a sky full of airliners. With lots of airplanes flying coast to coast on a 4D trajectory, for example San Francisco to JFK, if even one is off on timing (for whatever the reason), the ripple effect could be disasterous!!

The hoped-for benefits of 4D Trajectory Based Operations are improvement of air traffic operations by increasing the overall predictability of traffic; optimal operations for airlines (aircraft using preferred routes and levels); better service provided (due to ground-ground and air-ground interoperability); fewer trajectory distortions; Reduced costs (e.g. fuel and/or time); reduced emissions; and increased capacities (en-route and airport) by enabling controllers to safely handle more traffic with fewer conflicts; and advanced information.

But there are still issues that need to be addressed or solved. One such issue is limited effectiveness unless widespread and coordinated. If only part of a given trajectory is subject to TBO, the achievable benefit is limited since the optimized RBT trajectory will be, by definition, interrupted (off the optimized route) resulting in longer, erratic routes, more controller interventions and the creation of negative ripple effects in unpredictable ways. TBO limited to one’s own Functional Airspace Block (one Center’s airspace) is of lesser value if the trajectory extends beyond that center’s boundaries.

Example: An aircraft is traversing the airspace of three centers on its way from A to B. Each individual center’s routing turns out to be inefficient compared to the business trajectory (straight line with timed fixes) although the routing is optimal within each center. The situation could be even worse if there were several centers in the middle instead of just one, i.e., coast to coast It is also possible the preferred 4D trajectory by an aircraft operator may not follow the great circle between the point of departure and point of arrival. For example, to gain the benefit of a tailwind (or jet stream) en-route, or avois the jet stream, an operator may file a route that is tens of miles longer than the shortest route, but faster and more fuel efficient.

There are definitely technology challenges –

Equipment requirements for new aircraft and retro-fitting older aircraft, and possibly new equipment for the centers, TRACONs and airports.

Attitude change – Controllers will have to consider the impact of their actions on the trajectory as a whole, and pilots will have to accept more restrictions (the aircraft should reach certain points at defined times, not earlier and not later).

More challenging conflict detection – At present the airspace structure is such that most conflicts occur at specific points (e.g. airway crossings). With the introduction of TBO, aircraft trajectories will no longer follow standard airways and the conflicting points will not be at fixed locations, similar to free route operations. This should not be much of an issue if appropriate equipment is available to controllers since the number of conflicts is expected to be reduced.

Equipment failures – Sector capacities will be recalculated to reflect the use of TBO. This could easily lead to controller overload in case of equipment failure (a situation similar to surveillance system failure nowadays). Some of the equipment requirements include enhancements to the weather model in the Flight Management System, improvements to the FMS to improve the ability to meet time constraints, introduction of CPDLC, and the introduction of SWIM world-wide.

OCT. QUIZ : (Answers at the bottom of the Safety Program section.)

1. Is it possible to fly to a point defined as 0 degrees lattitude/ 0 degrees longitude ?
   1. Yeah, right!!!. Do I look that stupid?
   2. Of course you can..
   3. No way, negative, not possible.
   4. Even if I could, I don’t want to!
2. Alrighty now!! What is the speed of light??
   1. 186,280 Miles Per Hour.
   2. 186,280 KTs
   3. 300,000 meters per second
   4. 186,280 Miles Per Second
3. OK, we all know what ADS-B is, right? So what is ADS-C?
   1. There is no such thing.
   2. That is what provides incoming weather data to be displayed in my GPS/iPad.
   3. That is what provides the traffic to be displayed on my GPS/iPad.
   4. A bigger, better more capable, Big brother version of ADS-B
4. OK, you think you have finally memorized all of the FAA acronyms, right?? Well, what the heck is a stopway???
   1. The hold line at a taxiway.
   2. The hold line at the runway.
   3. The clearing at the end of each runway.
   4. The yellow chevrons at the end of the runway.
5. Another critical acronym nobody knows. What is ATCRBS?
   1. I Never heard of it, therefore it doesn’t exist!.
   2. Sometimes used by the pilot to transmit to ATC.
   3. A military system to track their own aircraft.
   4. A second radar antenna attached to the primary radar.

SAFETY PROGRAMS

Simply log on to the Internet and go to WWW.FAASAFETY.GOV, click on “Seminars” and start checking for any other upcoming seminars. Should you desire a particular safety or educational program at your local airport or pilot meeting in the future, such as the BasicMed program, our “Winter Wonderland” snow season special, ”The Aging Pilot”, Radio Phraseology, or my newest one on LIFR approaches, which discusses the how’s, why’s, and pitfalls of shooting an approach all the way down to minimums and missed approaches, simply call or text me at 410-206-3753 or email me at either This email address is being protected from spambots. You need JavaScript enabled to view it. or This email address is being protected from spambots. You need JavaScript enabled to view it..

Arizona Pilots Association provides the safety programs at no charge. We can also help you organize a program of your choice, and we can recommend programs that your pilot community might really like. There are also a lot of great webinars online, each about an hour long, and worth credits towards your WINGS participation. You might find one that is right up your alley or really “tickles yer fancy”!!

answers:

1. b. You would simply start anywhere on the O degree latitude line (the equator) and fly east or east to the prime Meridian, otherwise known as the 0 degree longitude line that runs north/south through Greenwich, England.
2. d. The speed of light traveling through a vacuum is exactly 299,792,458 meters (983,571,056 feet) per second. That's about 186,282 miles per second — a universal constant known in equations as "c," or light speed.

According to physicist Albert Einstein's theory of special relativity, on which much of modern physics is based, nothing in the universe can travel faster than light. The theory states that as matter approaches the speed of light, the matter's mass becomes infinite. That means the speed of light functions as a speed limit on the whole universe. The speed of light is so immutable that, according to the U.S. National Institute of Standards and Technology, it is used to define international standard measurements like the meter (and by extension, the mile, the foot and the inch). Through some crafty equations, it also helps define the kilogram and the temperature unit Kelvin.

But despite the speed of light's reputation as a universal constant, scientists and science fiction writers alike spend time contemplating faster-than-light travel. So far no one's been able to demonstrate a real warp drive, but that hasn't slowed our collective hurtle toward new stories, new inventions, and new realms of physics.

3. d. ADS-C Automatic Dependent Surveillance — Contract is the means by which the terms of an ADS-C agreement will be exchanged between the ground system and the aircraft, via a data link, specifying under what conditions ADS-C reports would be initiated, and what data would be contained in that data stream.

Description

Although the names are similar, ADS-C and ADS-B are two different applications.

Automatic dependent surveillance - broadcast (ADS-B), like Primary Surveillance Radar (PSR) and Secondary Surveillance Radar (SSR) is an ATS surveillance system which allows ATC to automatically and repeatedly access data from all suitably equipped aircraft and both use and re-broadcast it to suitably equipped other aircraft within range.

Automatic dependent surveillance - contract (ADS-C) uses the same systems on board the aircraft to automatically transmit similar information - aircraft position, altitude, speed, elements of navigational intent and meteorological data - only to one or more specific Air Traffic Services Unit (ATSU) or AOC [1] facilities for surveillance and/or route conformance monitoring.

Data provision by an aircraft is generated in response to a request within the terms of the ADS contract held by the ground system. This contract identifies the types of information and the conditions under which reports are to be sent by the aircraft. Some types of information are included in every report, while other types are provided only if specified in an ADS contract request. The aircraft can also send unsolicited ADS-C emergency reports to any ATSU that has an ADS contract with the aircraft.

An ATSU system may request multiple simultaneous ADS contracts with a single aircraft, including one periodic and one event contract, which may be supplemented by any number of demand contracts. Up to five separate ground systems may request ADS contracts with a single aircraft.

4. d. The stopway is the area that is placed right after the runway, and it is used when reducing speed if a takeoff is called off for any reason. Its width has to be at least the same as the runway and it should be able to help a plane slow down without damaging it. The stopway is centered on the runway extended centerline and the combined length of runway and stopway equals the ASDA, which is Accelerate Stop Distance Available.

Because they have limited use and are expensive to build, stopways are less cost effective in comparison to a full-strength runway that is functioning in both directions.

Stopways are depicted by big yellow chevrons on the ends of the runway.

5. d. ATCRBS – Air Traffic control Radar Beacon System. An ATC ground station consists of two radar systems and their associated support components. The most prominent component is the PSR. It is also referred to as skin paint radar because it shows not synthetic or alpha-numeric target symbols, but bright (or colored) blips or areas on the radar screen produced by the RF energy reflections from the target's "skin." This is a non-cooperative process, no additional avionic devices are needed. The radar detects and displays reflective objects within the radar's operating range. The second system (ATCRBS) is the secondary surveillance radar, or SSR, which depends on a cooperating transponder installed on the aircraft being tracked. The transponder emits a signal when it is interrogated by the secondary radar. In a transponder-based system signals drop off as the inverse square of the distance to the target, instead of the fourth power in primary radars. As a result, the effective range is greatly increased for a given power level. The transponder can also send encoded information about the aircraft, such as identity and altitude.

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