EBACE Convention News

APG Adds Dynamic Curtailment to W&B Calculations

 - May 20, 2017, 11:00 AM

For many pilots, dynamic curtailment is probably a new and unfamiliar term, but it is a factor that aircraft operators need to consider, and Aircraft Performance Group (APG) is here at Stand W118 to help explain the concept. APG is also highlighting its runway analysis capabilities and its iPreFlight iPad app, which helps pilots ensure the flight meets required margins of safety when taking off from hot and high airports. APG is also introducing the new Enterprise version of iPreFlight, which integrates with operators’ back-end computer systems to manage delivery of performance dispatch information to pilots’ iPads.

More customers are asking about our ability to support weight-and-balance dynamic curtailment,” according to APG CEO Mike Caflisch. Dynamic curtailment accounts for movements in flight from one place to another, for example, a pilot leaving the cockpit to use the lavatory or passengers moving around or a galley cart being rolled aft. “We model those to make sure when movements happen, the airplane does not get out of the center-of-gravity envelope,” he said. “It’s difficult for an operator to do this without a tool. You have to model all the movements, the moment calculations, and then write an engineering report to show what you have considered. [The APG tool] saves a lot of time.” APG still offers its standard weight-and-balance calculator in iPreFlight, and the dynamic curtailment feature is a premium add-on.

It’s not a new requirement,” Caflisch said, but oversight [by regulators] is becoming much more aggressive to make sure operators have these plans in place.

Operators who use dynamic curtailment to calculate weight-and-balance can achieve higher payloads by taking into account how items and people move around during flight in larger airplanes. “If you’re using standard passengers' weights [and locations], you might have to curtail the weight-and-balance envelope to account for movements,” said Caflisch. When dynamic curtailment isn’t used, the only way to maximize payload is to weigh each passenger and not allow them to move around during flight. “Nobody wants to weigh the boss; or their spouse,” he said. 

Airlines have been using dynamic curtailment for years, but in a zonal fashion, which works well because they are flying larger airplanes, and dynamic curtailment can be calculated within each zone. The Embraer Lineage 1000, for example, is set up in a zonal scheme on iPreFlight. But other jets use the specific location of seats and equipment, which APG programs into each customer’s aircraft files. 

APG’s iPreFlight software combines weight-and-balance calculations with runway analysis so that dispatchers and pilots can determine the maximum allowable payload for takeoff at a particular airport as well as view takeoff and landing performance numbers such as V-speeds, amount of runway needed, emergency return V-speeds and a graphical depiction of wind components. APG’s runway analysis takes into account, according to the company, “declared distances, runway slope, obstacles, weather conditions and more” to make the iPreFlight calculations in accordance with regulatory requirements. Using APG’s engine-out departure procedures, operators can operate at an increased maximum takeoff weight. The APG database includes more than 8,550 airfields and 2,400 engine-out departure procedures.

Users can automatically receive weather conditions via the Internet to make the calculations, or if Internet access is not available, for example, during flight when landing performance needs to be updated, iPreFlight also allows manual input of pertinent weather conditions. Once all the data is entered, the user can generate a Flight Book, which includes the runway analysis, weight-and-balance, takeoff and landing data card, weather and notams. The flight book can be shared via email or messaging services with dispatchers and other crewmembers. 

Each iPreFlight app is essentially tailored to the aircraft [that the user] operates,” said Caflisch. “It’s configured based on his specific version, what mods he may have and flight manual supplements he’s approved to use, [those are all] included in the performance model.” APG has created databases for almost all business aircraft—it also serves airline customers—ranging from King Air turboprops to large-cabin jets and VIP Boeing BBJs. “The King Air is about the low end in the business aviation market,” he said, although the company is considering adding a version of iPreFlight for single-engine turboprop pilots. 

The new Enterprise version of iPreFlight integrates the software with customers’ computer systems, so that companies with their own dispatchers can create Flight Books and push them to pilots’ iPads. Pilots can still modify the Flight Book if needed. Generally, customers with five to 10 or more aircraft will benefit from using the Enterprise version, according to Caflisch. “It saves a lot of preflight calculations,” he said. “The pilot gets into the airplane, opens the iPad and already has the Flight Book with the particulars for his flight, company documents, performance calculations, weight-and-balance, etc.”

Throughout the world, there are some challenging high-altitude airports where pilots can benefit from help with performance calculations. But even for more typical airports, there are still changing conditions that must be accounted for, Caflisch explained. “Part of the process that we push is you need to check performance on every departure. When you get into challenging airports with mountainous terrain or airspace restrictions, it’s more important to put yourself in a position where you’re safe if something bad happens.”

APG has also developed another new iPreFlight feature, a separate cold-weather operations app for determining adjustments to altitudes during instrument approach procedures when temperatures are colder than normal. The user will be able to enter an airport ID and the temperature and quickly see the necessary adjustments without having to run the numbers in the FMS or calculate the restrictions separately. The app will work offline, too.

Those interested in iPreFlight can download the app and try it out with a free trial subscription. “It gives them a no-obligation chance to check out the app and put it through its paces,” he said.