Military Flow Arrows
Military low flying takes place across most of the UK, often as low as 100 feet Above Ground Level (AGL) for helicopters and 250 feet AGL for fixed-wing traffic.
The highest concentrations tend to be below 1000 feet AGL, so General Aviation pilots are strongly recommended to remain above this height during enroute flight.
The flow arrows depicted on military low-flying charts are not depicted on CAA VFR charts, and there is no requirement for civilian pilots to observe the associated military regulations. However, it is good practice to know where these are in order to avoid any unnecessary or avoidable incidents.
Find out now if there are Military Flow Arrows in your area; they are identified as dark blue arrows in the link below:
Below is a report from the Airprox Board of an incident between GA and low-flying military traffic:
Military Flow Arrows Summary
Check flying charts.
Check eAIP 6-76 for dark blue arrows.
Stay above 1000ft AGL during enroute flight.