Windsocks and runways

The value of the windsock was brought home to me recently at my base airport. As I walked across the tarmac the northerly wind was behind me.

Then, with a sudden drop in temperature, the wind changed from north to a south-westerly of 10-15kt in the space of one or two seconds.

On the main runway a Warrior had been cleared for takeoff and the pilot proceeded but now with a tail wind. The pilot had not picked the change in the wind direction though the aircraft had been facing the windsock as it taxied to the launch point.

A taxiing twin was advised to turn around and make for a southerly takeoff. Be it the single or the twin, neither was approved for takeoff with a 10-15kt tailwind. In the event of an engine failure the results could have been exciting to say the very least – a 5kt tailwind limit is usual for light aircraft.

One of the catches of flying from a tower airport is that pilots can blindly follow what the automatic terminal information service (ATIS) says. If the weather changes markedly, such as in wind strength or direction, the tower operators may not pick up the change in time to alter the ATIS for a pilot taking off or landing to note it.

It is vital that a pilot is aware of the wind direction and strength for both the takeoff and landing, even at the run-up bay. It is not uncommon to see aircraft in the run-up bay with their tails to the wind. Why? Because the first aircraft into the bay faced the wrong way and others followed like sheep.

Aircraft are best faced into the wind so that the wind is running over the control surfaces, but more particularly so the airflow is running into the cowling air intakes to assist with engine cooling.

A downwind landing can end in disaster. And the questions must be asked: Is there enough runway to stop on? Can a goaround be achieved? Maybe not. So, into wind is best. And it’s also worth remembering that with a tailwheel aircraft a downwind landing may cause directional control problems.

With the latest non-tower airport procedures there is now formal approval for some operators to land downwind. OK for a turboprop that can use reverse thrust to pull up but that can confuse others into thinking that is the runway to use. Better to over-fly the field, visually check the windsock and land into wind.

For the landing itself I always get the student to check the windsock on late final to see if it is telling him anything he should be aware of. Wind strength and direction? Does he need more or less flaps or have a crosswind to counter? Now let’s look at runways.

In the early days of aviation aerodromes were all-over fields, meaning a takeoff was always into wind. Today we see more single-strip runways and, of course, they’re not always into wind.

During a discussion on this with a senior instructor, he said his philosophy was that if planning to use a singlestrip aerodrome and close to last light, he ensured he could divert to another suitable strip given daylight, endurance, wind and weather.

The reason? In case he couldn’t land at the original destination due to crosswinds, surface conditions or even a preceding aircraft having had a gear-up landing before your arrival – and gear-up landings happen more often than you may think.

In a recent case a retractable single was being taken for a local flight. The pilot took off and immediately raised the gear. Seconds later the engine stopped – the tank selected was empty and the gear was not lowered before the aircraft touched down on the runway.

Lessons from this event: 1. Always check visually and on the gauges that you have adequate fuel in the tank selected for the intended flight.

2. Keep the gear down in a single – and sometimes in a twin – until you are past the point where you can land on the remaining runway following an engine failure.

3. Always use the entire runway available so that if you have to land you still have some room for rollout.

Proper use of a runway embraces many factors: Have the correct flight manual; ensure the length of runway is sufficient for the aircraft and the conditions – for example, aircraft weight, the temperature, surface, flaps setting, slope, elevation, wind strength, direction and pilot technique.

And remember: “For takeoff have all the runway in front. Any runway behind is useless. ” n Contact Dave by email at flyer02@optusnet. com. au