Prevent weather-related issues

There are many reasons why a customer may have an urgent time-sensitive shipment they need to get to the destination. The shipment of pharmaceutical items such as vaccines and perishable goods such as food and plants all require the items to arrive without delay. Any delay of important equipment such as engines for aircraft on ground (AOG) can be measured in thousands in dollars for the airline. Critical health items such organs or blood may be a matter of life or death.

Many of these time-sensitive shipments are also temperature sensitive. Active temperature-controlled aircraft containers (ULDs) help maintain constant temperatures while in the cargo load and powered by electricity. Passive containers typically have time constraints associated with them. In either case, it's always advisable to avoid excessive heat or cold where possible.

In large population areas, you may have multiple airports at your disposal to choose from for the departure or arrival airport. If your shipment involves connection points, you have even more airports to consider. It's crucial to pick the airport with no adverse weather conditions and minimize potential delays.

Cirium Weather APIs can be integrated within your systems and applications to provide insight into current and expected weather conditions at airports around the world.

Audiences

  • Cargo

Platform

FlightStats APIs

TAF APIs

Cirium processes weather information that is published by airports around the world. The FlightStats Weather APIs return current and forecasted weather at an airport. This article focuses on the TAF APIs, but the additional weather APIs are described in the Additional Information section at the end of this document. We assume a common use case is that you are wanting to get a shipment to a destination within the next 24 hours. TAF APIs are the most appropriate for predicting weather conditions at airports for temperature-sensitive shipments within the next 24-30 hrs.

TAF stands for terminal aerodrome forecast and is the standard format used to publish weather forecast information for the area immediately surrounding an airport. TAFs are published by human weather forecasters and are concise strings of coded information. Our processes decode that information and present a more structured and easier to understand result.

A TAF report may contain information such as:

  • The airport the report is for, the time the report is published, and the time period the forecast covers
  • A base forecast describing wind, visibility, sky conditions, wind shear, temperature, icing and turbulence
  • Changes to the base forecast including the time period the change will occur and what is changing

Not every report contains all that information, and differences exist between what information is published depending on the country the airport resides in. For example, the United States does not publish forecasted temperature nor information on icing or turbulence.

Also worth noting, is that a TAF just describes the weather. It doesn’t describe the impact that the weather will have on flights arriving/departing an airport. This document will describe how a TAF report can be interpreted to understand impact better.

Calling the TAF for Airport API

Use the following steps to use the TAF for Airport API.

1) Get an application ID and key

To get started with TAF for Airport API, you first need to get an account, an application ID, and a key. See Get an evaluation account for more details on setting up an account. The TAF for Airport API is available in our commercial or contract plans, and we also offer a trial period where you can try it out.

Once you have your account, follow the instructions on Get started to acquire an application ID and key and to get familiar with the standard FlightStats API platform patterns.

2) Set up your request

The request to TAF for Airport is simple as it does not contain many options. You need to choose the format (json, xml, or jsonp) you want the information returned in, and the airport you want a TAF report for.

The following request is an example call that gets json data for DFW.

curl --request GET --url "https://api.flightstats.com/flex/weather/rest/v1/json/taf/DFW?appId=YOUR_APP_ID&appKey=YOUR_APP_KEY"

3) Parse the response

A sample response for the above query follows

Request

The first part of the response contains information about your request. This part may be helpful if the airport codes you provided aren’t found or get mapped to a different airport than expected. The request takes IATA, ICAO or FS airports codes and attempts to automatically map the airport. This can be controlled using the codeType parameter.

Appendix

The last part of the response is an appendix containing details on the airport. This appendix information can be used to present names in addition or instead of codes, as well as providing additional details about the airport.

TAF

The TAF object contains the forecast. The first portion contains the time the report was issued, as well as the time the observations for the report were made. These are usually the same. It also contains the airport code the observation was made for (also in ICAO format) and the original un-decoded TAF report. It then contains a number of forecasts. The top-level object also contains a reportType property which describes the type of report. This is usually ‘Normal' but may also be an ‘Amendment’ or ‘Correction’ if something was published incorrectly or needed to be changed.

The first forecast is the base forecast, and the following forecasts are time periods where conditions in the forecast are expected to change.

Each forecast contains a time period (start and end) that the forecast is valid for. There may be overlap. The type of forecast indicates what is happening with the weather conditions.

  • Base - The starting forecast for the period covered by this TAF
  • From - Prevailing conditions changing rapidly (within the span of about an hour) and continuing until end of forecast or further changes.
  • Temporary - Temporary conditions generally expected to last less than an hour at a time and taking up less than half of the indicated time period. Preceding conditions continue to apply unless overridden.
  • Becoming - Prevailing conditions changing gradually over a longer time period, usually about two hours.
  • Intermittent - Intermittent changes expected to occur for periods of less than 30 minutes.
  • Probability - Conditions expected to occur with a given probability during the stated interval. This is usually when the probably of an occurrence of conditions such as thunderstorms or precipitation in the 30%-50% range. In this case, the probability attribute is also set.

Looking through the example, the TAF report contained 4 forecasts (all times UTC):

  • The base forecast starting at 2022-06-03 21:00 and ending at 02:00 which contains some thunderstorms in the vicinity of the airport, scattered clouds and visibility at 6 miles or more
  • A temporary change occurring somewhere between 21:00 and 00:00 where some thunderstorms and light rain could be present
  • Prevailing changes occurring rapidly starting around 02:00 and lasting 20:00 where the wind decreases and the lowest level of clouds is at 12000ft
  • Finally, some more changes occurring rapidly starting around 20:00 and last until 2022-06-05 00:00 where the wind picks up a bit and scattered clouds are at 7000ft

Each forecast section contains a conditions section which includes information on wind, visibility, sky conditions (or cloud coverage), weather conditions present, icing, turbulence, and barometric pressure. The amount of information available is dependent on the country the airport resides in, what is being forecasted, and ultimately the human that is providing the weather forecast.

4) Determine Weather Impact

To determine the impact to time-sensitive cargo, you need to first find the forecast period where your shipment will be departing and/or arriving. The information within that time period can help predict whether you are likely to experience problems with delays or irregular events such as cancelations or diversions.

Wind Speed and Direction

Wind speed can be very disruptive. Determining impact can be complicated because it depends on runway configurations, whether the wind is a headwind, tailwind or crosswind and if the flight is departing or landing. Strong headwinds are great for take-offs as it helps lift the flight into the air. They are great for landings as well as they help slow the plane down. Strong tailwinds aren’t so great for take-offs as it means more runway is required to get lift. Landing is more complicated with strong tailwinds as they increase the ground speed of an aircraft and thus the amount runway to slow down. Crosswinds are dangerous in both takeoffs and landing, and wind gusts complicate both as well. Wind shear (a significant change in wind speed or direction in a short amount of time) can be potentially dangerous. High wind speed also affects ground operations.

Wind in combination with other weather conditions (rain, snow, ice, thunderstorms, etc.) also impact the amount of wind that planes can handle.

In general, anything including winds gusts above 20kts could be a potential flag of caution. More serious delays occur around 30kts. Above 45kts and airlines won’t even be able to open the cargo doors. Again, this depends a lot on wind direction, wind gusts/sheer and type of aircraft and runway conditions.

Visibility and Ceilings

Ceilings are usually defined as the lowest level of broken or overcast skies. Generally speaking, if the cloud ceiling is > 3000 ft above ground level and visibility is > 5 miles, then flights are flying with visual flight rules (VFR) and the airport is generally operating normally. The airport departure/arrival rates begin dropping at lower visibility or ceilings.

  • Marginal VFR is between 3- and 5-miles visibility and/or ceilings between 1,000 and 3,000 ft.
  • Flights need to be flying with instrument flight rules (IFR) at any visibility less than 3 miles and/or ceiling less than 1000ft.
  • Low IFR is at visibility less than 1 miles and/or a ceiling less than 500ft.
  • Very Low IFR is at visibility less than 1/2 mile and/or a ceiling less that 200 feet.

IFR requires additional training, equipment and demands more from the pilot. Airport departure/arrival rates drop significantly under IFR. Air traffic control will most likely introduce ground control programs and other measures that hold some flights at the departure point.

Weather Conditions

Weather conditions (rain, haze, snow, clear skies) clearly affect an airport. Problematic weather should be called out as potentially disruptive. Thunderstorms in particular almost always disrupt flights. Most of the phenomena described in the weather conditions object can be potentially disruptive. Spray, Drizzle, haze and rain are the least impactful. The more intense the condition, the more likely it’s impactful. Heavy rain for example could impact flights. It’s also somewhat dependent on the airport. Light snow in Chicago for example is less likely to have an impact than light snow in Portland, Oregon where the airport is not used to getting snow.

Icing or Turbulence

Moderate to high intensity icing or turbulence in the area of the airport may obviously impact flight performance and reasons to indicate to your customer potential problems.

5) Display TAF information within your application

There are several ways TAF information could be displayed. The simplest is just exposing an airport lookup and making the request at that time. Another way is to regularly poll the TAF APIs for updated information for major airports and cache that information within your application. That information could then be used to power a visual like a dashboard, or to mix in with the results of a Schedules API or Connections API call.

Pro tip

As stated earlier, TAF information is usually only published 4 times day (every 6 hrs). As such, if you have a cache of a number of airports, there’s not a need to poll the API at a high frequency. However, amendments and corrections can occur, so consider polling every half-hour or hour just in case.

Additional information

Cirium processes weather information that is published by airports around the world. The FlightStats Weather APIs return current and forecasted weather at an airport. The weather information published includes:

  • METAR - A METAR report contains current weather conditions at an airport and is generally published once or twice an hour, though some airports may report less or more frequently. The information contained within a METAR is very similar to what a TAF report shows but is current conditions and not forecasted.
  • TAF - A TAF report contains forecasted weather for the area surrounding the airport. They are usually published four times a day (every 6 hours) and contain information for the next 24-30 hours.
  • Zone Forecast - This is the more standard 5-7 day forecast for the area around an airport. This information is only available for airports within the United States.

FAQs

What is the Weather API?

Resources

The FlightStats APIs provide a set of status and positional APIs by flight, airport, fleet, route, or area. They also include schedules, airline reference, airport reference, ratings, delay index, and weather information.

The Airport Delay Index APIs return a measure of the level of departure delays a airport is currently experiencing and are a good complementing set of data for applications display delay information.