What is Decrease (MET) in Aviation? Decrease (MET), abbreviated as DCR, is a critical term used in meteorological aviation reports that signifies the reduction in certain weather parameters over a specific time frame. This term has essential implications for flight safety, planning, and operations. Understanding Decrease (MET) is crucial for pilots, air traffic controllers, and meteorologists as it helps forecast rapid changes in weather conditions which could affect aircraft performance and flight routes.
Understanding Decrease (MET) in Aviation
Decrease (MET) or DCR is a meteorological notation commonly found in Terminal Aerodrome Forecasts (TAFs) and meteorological reports (METARs). It quantifies the decline in certain weather elements such as visibility, wind speed, temperature, or cloud cover within a specified period. For example, a DCR of visibility from 10 kilometers to 4 kilometers over one hour indicates a significant decrease that could impact flight operations.
The DCR acronym is used globally to maintain standardized communication between meteorologists and aviation personnel. Aviation weather is highly dynamic, and small changes rapidly affect aircraft landing and takeoff safety. The inclusion of Decrease (MET) notations helps pilots anticipate deteriorating conditions early and adjust their decisions accordingly. For instance, if the visibility is decreasing sharply, alternate routes or delayed schedules might be planned to ensure safety.
Significance of Decrease (MET) in Flight Operations
The role of Decrease (MET) (DCR) is integral to flight safety and efficiency. It provides data that pilots depend on to evaluate the risks associated with different phases of flight, especially during landing and takeoff. For example, a rapid decrease in ceiling height from 2500 feet to 1500 feet within 30 minutes can impose instrument approaches where visual flight rules (VFR) were previously sufficient.
Flight dispatchers use DCR data to adjust flight plans and optimize fuel consumption by avoiding adverse weather zones. Furthermore, decreased visibility or wind changes captured by DCR can influence decision-making at air traffic control centers, which prioritize safe sequencing of arrivals and departures. The use of Decrease (MET) informs contingency strategies and precautions, reducing the likelihood of weather-related incidents.
Technical Aspects and Monitoring of Decrease (MET)
Decrease (MET) involves specific numerical thresholds and time frames defined in meteorological documentation. According to the World Meteorological Organization (WMO), a decrease qualifies as significant if visibility drops by more than 50% within one hour or if wind intensity changes by over 10 knots within 30 minutes. Similar thresholds apply for temperature drops, such as decreases of more than 5 degrees Celsius per hour.
Modern aviation relies on automated weather observation systems (AWOS), radar, and satellite data to identify decreases efficiently in real time. These systems continuously feed updated METAR and TAF data into centralized aviation weather networks. This capability enhances predictive accuracy, allowing for timely dissemination of critical DCR information. More information on aviation weather terms and reports can be found at the [International Civil Aviation Organization (ICAO) Meteorological Service](https://www.icao.int/safety/meteorology).
In practical application, the DCR indicator is found in METAR or TAF strings, often followed by the type of weather parameter and the numerical range. For example, a TAF might read, “BECMG 1213/1215 3000 -RA DCR VIS 5000,” indicating a decrease in visibility from 5000 meters over the forecast period. Pilots and weather forecasters interpret these symbols to anticipate and respond to degrading atmospheric conditions.
