Category Archives: explainer

EXPLAINER: Convective weather in the tropics

Bloomberg has a lengthy, general-interest article about the weather-related problems faced by aircraft flying between the northern and southern hemisphere (i.e. AF447):

Violent weather in the region can approximate the supercells that spawn tornadoes in the U.S., which exceed altitudes of 50,000 feet, NOAA’s [Pat] Slattery said.

“We are eons ahead in forecasting convective storms in the central part of the U.S. than we are in forecasting them in the tropics,” said National Weather Service’s [Jason] Tuell. “So much of it takes place over water in the tropics — over the Indian Ocean, Pacific and Atlantic — and there is just much less data available because of that.”

There is also a brief discussion of Honeywell’s “IntuVue” 3D weather radar product:

[Honeywell’s] three-dimensional systems, introduced less than three years ago, are in a small portion of the commercial aircraft fleet, said Chris Benich, director of aerospace regulatory affairs at the world’s largest maker of airplane controls. Among airlines using IntuVue are Cathay Pacific Airways, Air Canada and Singapore Airlines Ltd., while the U.S. Air Force uses it on C-17 cargo planes, according to a list provided by Honeywell. The cost for long-haul aircraft such as the Boeing 777 is about $335,000, said Bill Reavis, a Honeywell spokesman.

Most commercial planes are equipped with two-dimensional radar that requires pilots to manipulate it to get an accurate picture of the weather, Benich said.

“With older weather radars, pilots have difficulty accurately determining the top of significant weather,” Benich said.

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EXPLAINER: Everything you ever wanted to know about SESAR

Aviation Week’s David Esler has a very well-researched and in-depth article about SESAR, the European Union’s version of NextGen. It provides a lot of detail about how the two approaches differ (one example: NextGen implementation is being driven by the federal government, while SESAR is being driven by industry partnerships), and also examines questions of harmonization.

Interestingly, one of the key themes is “who’s further ahead?” See the following excerpt:

[On the topic of] who’s leading the parade toward 21st century ATM reform – both SJU [SESAR Joint Undertaking] and FAA solons diplomatically refused to describe themselves as ahead. Here’s what the SJU’s [Executive Director] Patrick Ky had to say: “We are maybe more advanced in how we want to organize our technical activities, whereas you in the United States are more advanced in the implementation of ADS-B. We have different contexts and different relationships with industry, but I think we are making sure with the FAA that we are moving in the same direction and fully in line with each other’s priorities.”

For the FAA perspective, we interviewed Steve Bradford, chief scientist of architecture and NextGen development. “That’s not accurate at all,” Bradford said when we queried whether the SJU was setting the pace in implementing ATM technology. “I’m not going to say we’re ahead, but we are spending money and have a full ADS-B implementation in progress and will have full service by 2013. And our new automation program, ERAM [En Route Automation Modernization], is ahead of schedule.”

We think any discussion of “who’s further ahead” is a bit like asking who’s winning a marathon at mile marker two.

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EXPLAINER: Avionics at the leading edge of performance navigation

Aviation International News has an outstanding wrap-up of the state of flight management systems (FMS) that offer  easy pilot control and core capabilities that set the stage for performance-based navigation (PBN).

Flight management systems have never been considered simple pieces of equipment, but the technology is quickly evolving beyond basic navigation and performance functionality to include a host of new capabilities that hold the promise of changing the way pilots fly for the better.

Absent from some of the latest integrated avionics systems are the bezel-mounted control display units (CDU) flight crews have known since the 1970s. Instead, many modern business jets and some of the latest airliners are integrating FMS controls with the flight displays and cursor control devices (CCD), allowing pilots to point and click their way through a variety of menus or drag and drop any portion of their flight route (a technique known as “rubber-banding”) to include or modify a waypoint. The changes are resulting in cockpits that are more intuitive than those of the past–and even those of the present, in many cases–while packing more capability than ever before.

At the same time, hardware and software upgrades available from FMS manufacturers are opening the possibilities for complex, curved RNP (required navigation performance) procedures and the latest WAAS LPV (lateral precision with vertical guidance) approaches. The changes expand the operational capabilities of properly equipped airplanes today while serving as a cornerstone for future operations in so-called NextGen airspace.

Required navigation performance will be a key element of NextGen airspace. The benefit of a so-called RNP SAAAR [special aircraft and aircrew authorization required] approach is that it can carve out a highly precise, curved path through the sky that usually results in lower landing minimums–sometimes much lower. But gaining approval is a costly and complex endeavor requiring submittal of monthly operational reports to the FAA, pilot simulator training and operations manual revisions. Considering that fewer than 100 RNP SAAAR approaches have been published so far, most operators probably won’t go to the trouble of gaining approval until their home airport has an RNP approach. But as more RNP procedures are created, operators who forego such approvals will be at a disadvantage compared with those who are SAAAR compliant.

To assist operators seeking to upgrade to RNP capability, Honeywell has launched Go Direct, a consulting service designed to help business jet operators take advantage of new RNP SAAAR procedures the FAA is adding at scores of airports around the U.S. The agency plans to publish 60 new RNP SAAAR procedures per year for the next two years. Some airports scheduled to receive an RNP approach in the next 12 months include Teterboro, N.J.; Aspen and Eagle, Colo.; Monterey, Calif.; and Scottsdale, Ariz. If your home airport or an airport you use often offers an RNP SAAAR approach, the approval can mean the difference between landing or having to execute the missed approach and consider other options.

The major advantage RNP procedures have over other types of approach is their tighter lateral boundaries, which allow the creation of curved pathways through mountain valleys or by using so-called radius-to-fix (RF) turns to avoid terrain or obstacles. The RNP SAAAR approach to Atlanta DeKalb-Peachtree Airport (PDK) is a good example of the benefits RNP can provide. The approach to PDK’s Runway 2R incorporates a continuous descending turn designed to avoid the tall towers that block the straight-in approach to the field. Due to the east-west flows at nearby Hartsfield-Jackson International, a straight-in ILS or WAAS LPV approach to this runway would be hard to implement, even if the obstacles southwest of the airport were removed.

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EXPLAINER: The state of performance-based navigation

FlightGlobal’s Aimée Turner has an excellent, multi-part overview of what’s happening in the fast-moving world of performance-based navigation (PBN). The centerpiece is this article, which brings home the point that all industry players — airframers, ANSPs, regulators, airlines — must pull together in order for the hoped-for cost and carbon savings to emerge. And even that may not be enough:

The Intergovernmental Panel on Climate Change’s (IPCC) influential report on Aviation and the Global Atmosphere said in 1999 that improvements in air traffic management and other operational procedures could reduce aviation fuel burn by up to 18%. The influence of ATM over CO2 emissions was estimated at 12%.  [..]

Phil Stollery, chairman of the [Civil Air Navigation Services Organisation] environment working group, frames those IPCC figures, however, in light of a recent CANSO study that has given the industry much greater clarity in terms of ATM’s potential contribution to the efficiency debate.

Stollery explains that efficiency in this sense is the difference between the exact point-to-point distance of a flight at the most fuel efficient altitude and speed, and the actual flight mileage flown.

“One of the things we wanted to do was to put the record straight. The IPCC report estimated that ATM had an influence over 12% of system inefficiencies and our report reflected back on that. We reckon that between 1999-2005, improvements allied to a better overall assessment, as well as the introduction of initiatives such as RVSM, generated a 4% improvement in system efficiency and that on average the global ATM system is operating at around 92% efficient today,” he says.

That is 4% down with 8% still to go.

“Of the remaining 8%, half is locked up in interdependencies. The other half, 4%, we have set at the goal to recover, which amounts to an ambitious target considering forecast growth.”

The same piece also features an excellent sidebar explaining PBN, RNAV, and RNP concepts – it’s one of the best we’ve seen.

Separately, the series also features an article about Southwest Airlines’s efforts to aggressively adopt PBN technology and procedures.

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FAA ATO releases new NextGen explainer video

The FAA’s Air Traffic Organization has put together a 6-minute video illustrating how commercial air traffic is handled today, and how this will change under NextGen.  The video is called “NextGen Gate to Gate,” and you can find it here.

UPDATE: Wired’s “Autopia” blog picked up this story, calling out the video’s cheesy production values but nonetheless expressing support for NextGen generally.

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Everything you ever wanted to know about ERAM

Aviation Week has a fine overview of the soon-to-be-deployed En Route Automation Modernization system. A brief excerpt:

[The] ERAM system, developed by Lockheed Martin, represents one of the most complex and expensive upgrades the FAA has ever undertaken. ERAM is expected to begin controlling live traffic at the FAA’s Salt Lake City center late this month or early April, and at the Seattle center a few weeks later. Once the system has checked out at these two sites, it will be rolled out nationwide to the remaining 18 en route centers.

While problems remain as the operational date draws closer, they are not atypical at this point in such a large project, stress Lockheed Martin and FAA officials. The $2-billion ERAM effort is on schedule and within budget – something of a rarity for a major FAA modernization project.

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Explainer: CDA at Atlanta-Hartsfield

The science and technology website has a brief but interesting article entitled “Continuous Descent: Saving Fuel and Reducing Noise for Airliners.” An excerpt:

Proponents hope the 90-day test at Hartsfield-Jackson Atlanta International Airport – currently the nation’s busiest airport – will move the concept one step closer to nationwide implementation. Estimates suggest that continuous descent arrivals could save a large airline as much as $80 million per year in fuel costs alone.

“In commercial aircraft, we see anywhere between 300 and 1,000 pounds of fuel saved for each arrival,” said John-Paul Clarke, director of the Air Transportation Laboratory at Georgia Tech and an associate professor in the School of Aerospace Engineering. “With fuel cost at $3 per gallon, that would amount to as much as $600 per arrival and could really add up for the airlines at a time when they need all the savings they can get.”

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Hot topic: biofuels in jet aviation

Two good articles in the New York Times and Scientific American on the current interest in alternative aviation fuels, hooked to this week’s upcoming Continental B737 biofuel flight test.

NYT: Continental plans to have the crew turn off and restart the right engine, the one running on the 50-percent blend of ordinary jet fuel and plant-based fuel. The crew will simulate breaking off an approach and going around, which demands high power from the engines, among other maneuvers. On board will be two pilots, a flight engineer and, because this is an experiment, 157 empty passenger seats.

Although jet fuel prices have dropped with crude oil, industry executives say they are determined to become less dependent on a single source of fuel in case prices rise again.

“It’s hard to plan a business, and buy expensive pieces of equipment that last for 20 or 30 years, when you have total uncertainty about the cost of your biggest expense,” said John P. Heimlich, chief economist of the Air Transport Association, the trade group of the major airlines.

SciAm: “We can use any kind of vegetable oil—palm, jatropha—they all have the same [chemical] backbone,” [says UOP chemist Jennifer Holmgren.] “We just adapted what we tend to do in an oil refinery for this application. This is not rocket science, we feel very comfortable scaling this up.”

She adds, however, that this fuel is not a “drop-in replacement” for Jet A1. That’s because jet fuel from petroleum contains so-called aromatics—hydrocarbon rings—that interact with the seals in current engines, helping swell them shut. “We don’t make aromatics through the vegetable oil route,” she says. “If we wanted to fly on 100 percent [biofuels], there are issues around O-rings and things like that.”

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Explainer: Why weather is at the heart of NextGen

An excellent set of in-depth articles (start here, continue here) by Aviation International News’ Jennifer Harrington, focusing on the critical role that weather is already playing in shaping the NextGen project.

A brief excerpt:

Weather forecasters will no longer analyze reams of data in an attempt to produce a single, uncertain forecast. Instead, the forecaster of the future will oversee an automated forecasting system that will produce a “probabilistic weather forecast.” In other words, the system will produce different scenarios based on the probability of a certain weather event occurring. “Today we have only one plan, so it tends to be conservative,” [the FAA’s Steve] Bradford said. “The [weather] automation would run through a number of different potential futures and help us come up with a plan that would allow us to maximize the use of the airspace around an airport and minimize the chance of diversions. We could plan continuously and increase efficiency.”

Among those quoted extensively: Bruce Carmichael, director of the Aviation Applications Program  at the National Center for Atmospheric Research (NCAR); Steve Bradford, the FAA’s chief scientist for Architecture and NextGen Development; Robert Gillen (Ensco’s director of engineering) and Christina Frederick-Recascino (Embry-Riddle’s VP of Research), both of whom are involved with the Daytona Beach NextGen testbed facility.

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Explainer: Wide Area Augmentation System

Do you know exactly what WAAS is, and what sets it apart from regular GPS? Could you explain it in a few sentences?  If not, this FAA fact sheet is for you.  Clearly written, and also includes a brief history of how WAAS was developed and deployed.

Interesting tidbit: according to the FAA, WAAS approaches now outnumber traditional ILS approaches.

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Explainer: Clean air turbulence

A great column in Forbes magazine about what clean air turbulence is, why it happens, why it’s hard to avoid, and how meteorologists might soon be able to do a better job of predicting it. No specific mention of NextGen, though the author makes the point that one of the problems today is the low-resolution nature of aviation forecasts. Clearly, if the visionaries in the FAA weather group have their way, this should change within a couple of years.

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Explainer: ACARS and its future

Among the many legacy networks that NextGen initiatives will presumably replace, the Aircraft Communication Addressing and Reporting System (ACARS) stands out as especially anachronistic in a wifi- and WWAN-enabled world. This system, which uses 100- to 200- character “telex-style” messages for 2-way data transmission between commercial aircraft and airline operations centers, is slow, expensive, and poorly suited for data-intensive workflows. This well-written article from Overhaul & Maintenance magazine explores the options for replacing ACARS; if you’re interested in learning more about the system, it’s also worth taking a quick look at this clear and comprehensive Wikipedia entry.

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