Gunnar Fahlgren

As an answer to comments I have got, regarding tail wind, I will clarify my point of view with this statement.

I never say that an accident is caused by tailwind.

I only say, that it happens in tail wind.

Statistically there seems to be a much higher risk for an accident to happen in tail wind compared to accidents in head wind. And what I try to do is to give an explanation to why tail wind is a contributing factor. 

An other comment:

Assume VREF=110 kts. With a 10 kt head wind at 15 ft in the touchdown zone, groundspeed is 100 kts. With 10 kt tail wind it is 120 kts. The energy of the airplane is 44% higher and substantially longer runway would be needed. But if calculations show that available field length is adequate, where is the problem?

And my aswer:

Your calculation is correct. The problem is that VREF and height over the runway end are not reached in an approach with tail wind in the approach area. The tail wind on ground is not so important. It is the wind during approach, which will cause problem.

If stabilized on glide path and speed the aircraft might be landed short when the tail wind suddenly is reduced close to ground or if not so, the aircraft might come in “hot and high” and make a long landing.

That tail wind effect in combination with a wet and/or slippery runway or no manual extension of spoilers will cause problems if the pilot dos´nt make a go around.

Gunnar

An other comment: "Sudden reduction" applies to wind shears, right? I'd use correct terminology, or readers can be misled.

My answer:

Maybe you are right, but for me a wind shear is a sudden change of wind direction. A sudden change of wind speed you always have in all approaches both in head wind and in tail wind, when the wind speed is reduced closer to ground due to orography

Gunnar