Avionics June18.qxp_Layout 1 22/05/2018 15:50 Page 3
OPERATING T AVIONICS
The Common Denominators
The FAA's FIS-B resembles many commercial weather services, but with some important differences. First, an aircraft needs an ADS-B In receiver to receive 978 MHz broadcasts, and a display capable of showing the products. Basically, FIS-B delivers information ranging from text (airport conditions, etc.) to graphic representations of weather radar. Indeed, one of the most-coveted benefits of graphical weather over in-flight radar is its scope. When using FIS-B an operator can scroll around the map and see weather far beyond the range of airborne weather radar. Figure A (right) provides an inventory of FIS-B products.
Figure A: Inventory of FIS-B Products PRODUCT
Airmen's Meteorological Information (AIRMET)
&RQYHFWLYH 6LJQLƓFDQW Meteorological Information (Convective SIGMET)
6LJQLƓFDQW 0HWHRURORJLFDO Information (SIGMET)
The Limitations of Today’s Weather Overlays
Whether from FIS-B or another service supplier, use of weather radar and other information should be utilized with a full understanding of its limitations. FIS-B information (including weather information, NOTAMs and TFR areas), are intended for advisory use only. The system lacks sufficient resolution and updating capability that is necessary for tactical aerial maneuvering around localized weather phenomena. In extreme scenarios, the oldest weather radar data on the display can be up to 20 minutes older than the display's age indication. This latency occurs because of the mechanics of how radar and other data come into the system. Doppler weather radar makes six one-minute swings to obtain a full image of weather, from ground-level up into the flight levels. The graphics from those six scans are combined and distributed for broadcast. By the time the process starts anew as much as 20 minutes may have elapsed from the start of the first sweep of the radar antenna. At its best the images a pilot sees from FIS-B are six minutes old. Furthermore, pilots cannot claim to have obtained a standard pre-flight weather briefing on the basis of having FIS-B weather information in front of them. Nevertheless, used regularly FIS-B can deliver life-saving weather information unlike that in any other system, whether shown on a cockpit display or tablet computer. Used wisely graphical weather can make a day's travel more productive than it might otherwise have been. T 98
AVBUYER MAGAZINE – June 2018
DESCRIPTION A weather advisory issued by a meteorological watch office for aircraft, advising on weather that is potentially hazardous to low-level aircraft/aircraft with limited capability. AIRMETs cover less severe weather than SIGMETs, such as moderate turbulence and icing, surface winds of 30 knots, or widespread restricted visibility. Issued for an area of thunderstorms affecting an area of 3,000 square miles or greater, a line of thunderstorms at least 60 nautical miles long, and/or severe or embedded thunderstorms affecting any area that are expected to last 30 minutes or longer. A weather advisory that contains meteorological information concerning the safety of all aircraft, including severe or greater turbulence over a 3,000-square-mile area, severe or greater icing over a 3,000-square-mile area, IMC conditions over a 3,000-square-mile area due to dust, sand or volcanic ash.
Aviation Routine Weather Report (METAR)
Contains data for the temperature, dew point, wind speed and direction, precipitation, cloud cover and heights, visibility and barometric pressure. Reports are typically generated hourly.
SPECi
A Special METAR generated if conditions change significantly within the hour.
Continental US Next Generation Radar (NEXRAD) Distant Notice to Airmen (D-NOTAM) Flight Data Center Notice to Airmen (FDC-NOTAM) Pilot Reports (PIREP)
Detects precipitation and atmospheric movement or wind. Returns data which, when processed, can be displayed in a mosaic map which shows patterns of precipitation and its movement. Information requires wide dissemination: en route navigational aids, civil public use landing areas and aeronautical data. Information that is regulatory – changes to charts, procedures and airspace usage. A report of actual weather conditions encountered by an aircraft in flight.
Special Use Airspace Status (SUA Status) Terminal Aeronautical Forecast (TAF)
Issued four times per day.
Amended TAF (AMEND)
Issued when the current TAF no longer adequately describes the ongoing weather, or the forecaster feels the TAF is not representative of the current or expected weather.
Winds & Temperature Aloft TIS-B Service Status
Computer-prepared forecasts of winds and temperatures aloft. Provides periodic status of TIS-B service via FIS-B UAT uplink.
The FAA added the following four new FIS-B products in 2017: • Lightning • Turbulence • Icing • Cloud Tops www.AVBUYER.com
Aircraft Index see Page 129