Before launching your flight, you should always run pre-flight predictions to get an idea on where your flight will be travelling to. There are many online calculators to help you with this. Most will allow you to run your flight predictions beginning 7 days prior to your launch date. This will help you decide whether or not it is safe to launch and/or whether or not your need to move your launch site to a different location or adjust your balloon’s size or ascent rate to avoid hazards. For example, if the flight path passes over an airport or large body of water, you should consider changing your launch location, your balloon size/fill, or waiting a few days for a different wind profile. Ideally you want to land in open farm land. This allows for a safe and easy recovery.
The most popular online flight prediction tool is the Cambridge University Spaceflight (CUSF) Landing Predictor. In our experience, this prediction tool has been very accurate and will usually give you a landing estimate that is within about 5 miles from the actual landing site. Although it is rare, it’s not unusual for the prediction to be off by upwards of 20 miles so when planning your flight, you should ensure that you have at least 15 miles or more between the predicted landing site and any major hazards like big cities, airports or large bodies of water. We recommend running multiple predictions with various parameters so you can identify a trend. This will give you insight as to where the payload could land if the flight ends sooner or later than you expected. One of our favorite secondary prediction tools we use to help with this is the University of Southampton ASTRA High Altitude Balloon Planner. This tool allows you to run multiple prediction variations (we run 250 each time) at once and will give you a heatmap of your landing zone so you can see and plan for the possible margin of error.
Most flight predictions tools use the Global Forecast System (GFS) weather models to supply their predictions. These tools are updated every six hours with new weather data so you can run multiple updated predictions as your launch time approaches. New weather models are published at 04:00 UTC, 10:00 UTC, 16:00 UTC and 22:00 UTC. The predictions tools are usually ready to provide a prediction with the updated forecast about 45 minutes after the new weather model has been published so you can run new predictions starting at 04:45 UTC, 10:45 UTC, 16:45 UTC and 22:45 UTC.
Flight Predictions Tools: