Using Grass Airfields in the Winter
If you live in a country where winter MEANS winter (like me. I’m in the UK), then typically it can add an extra challenge to flying. Usually there will be a greater chance of wind, rain, snow, low cloud, poor visibility, cold temperatures and low light.
Of course we can also experience many glorious crisp, clear days in the winter which are a joy to fly in.
And equally, many countries are not affected so much by these factors.
However, for the purpose of this article, I am assuming at least some of the issues exist where you are.
In the winter the more challenging weather conditions can add an extra problem when using grass airfields. I know a lot of you will have trained on grass runways and call them home for your flying. Personally, I fly from a commercial 1.5 mile long runway, so it’s no issue when there’s a bit of rain on the ground. But if I want to go anywhere, considering the ground conditions is a major factor for grass airfields in the winter.
Is It Open?
Before even considering whether the conditions will allow you to fly to or from a grass runway, the first step you should take should be to check with the airfield operator. They will be able to tell you if if the airfield is open and, if so, the current condition of the runway and recent reports from pilots.
What Conditions Affects Grass Airfields
Every airfield is different and has its own unique conditions, and these will determine how it copes with adverse weather and periods of rain.
Rain is one of the most common reasons that a grass airfield will be unsuitable for flying as it can lead to waterlogging and areas of mud on grass runways. Typically it is not advised to use a runway shortly after a period of rainfall, when standing water is most likely to have accumulated; acceleration through wet grass can be very sluggish. Experienced pilots will have their own limits when it comes to standing water and mud on a runway, but in general these conditions should be taken with extreme care; an airfield owner will often declare the runway closed when contaminated by water. The quality of the soil and any drainage system could mean waterlogging disperses in either hours or days.
Ice is not as common an issue on grass, however when it causes standing water to freeze it will make a runway unusable.
Snow and slush can add a whole new dimension to grass runway surfaces. From an operational perspective they can add increased friction and longer takeoff distances, and they can also cause problems with directional control. And if you’re flying into a grass airfield that is covered in snow, it can be pretty hard to spot the runway when the whole world has turned white, unless some obvious clearing has taken place.
Following snow the melt water can cause an airfield to become waterlogged.
I haven’t touched yet on how different aircraft types are affected by winter conditions on grass airfields. Generally, tail draggers are better at handling grass airfields than aircraft with tricycle landing gear, and this is true in poorer conditions, with no chance of the nosewheel digging into soft ground. But the considerations explained below still mostly apply.
Considerations for your Flying Technique
Let’s take a journey through a flight to think about a grass airfield affected by winter conditions.
Before takeoff, careful calculations should be made to determine the takeoff distance and run available, and what your anticipated performance will be based on aircraft type and weight in the given wind and runway conditions. Add to this a generous safety margin for slower acceleration, and plan the stop distance available (this should be 2.6 times the takeoff distance on grass).
Similarly, you should calculate your landing distance in the destination runway conditions. Anticipate the landing distance to be 40% longer than on dry grass (here’s a handy calculator).
Taxiing for takeoff, you notice it takes a bit more power to get moving, and whenever you hit an area of mud the aircraft slows down to the point of stopping. It is important to keep the aircraft moving, assuming it is safe to do so without endangering other aircraft or entering the active runway, to avoid becoming stuck in the mud.
This is true for your run-up too. Where possible, perform checks and run-ups whilst the aircraft is moving.
Now, it’s time for takeoff. All of the usual rules for grass runways apply, but with mud and a wet runway your takeoff run is going to be longer than usual. Try to avoid running through puddles and patches of mud, and be ready to abort if significant airspeed is lost.
Approaching your destination airfield, and aware from calling the owner ahead of your flight that the runway is wet, you prepare as normal for a slow, controlled approach, looking ahead for any problem areas on the runway.
Landing, you keep your nosewheel off the ground at first, and gently lower it. Any areas of standing water may cause the aircraft to aquaplane when travelling at speed; it is imporant not to use brakes where possible to avoid skidding, and to avoid the nosewheel sticking into the soft ground.
Taxiing to the parking area should again be done slowly, but avoiding stopping so as not to get stuck in the mud.
To Fly or Not To Fly
The decision to fly into or out of a grass airfield in adverse, winter weather conditions is always up to the airfield owner and the pilot in question. Every experienced pilot has their own limits based on their experiences of flying in different conditions, at different airfields, and in different aircraft. This should be taken into account when deciding whether to fly, particularly if it is to an unfamiliar airfield. It is always best to err on the side of caution and have a plan for the flight, including studying the airfield, discussing conditions with the owner and other pilots, and having a diversion airfield planned.
What tips do you have for flying in winter conditions on grass, sand and gravel airfields? Leave a comment below!