Zaibatsu wrote:Your airspeed should be +1/2 the gust and -0. Fly faster during gusty conditions since it will give you more margin above the stall and more positive control. Plan a longer round out and roll out and try to time touchdown between gusts.
Adjusting airspeed by applying the gust factor correction is a large aircraft SOP and so care should be taken when applying it to small aircraft. Large aircraft have lots of inertia and therefore take time and distance to recover lost airspeed or shed extra airspeed. Light aircraft have much less inertia and therefore less requirement to have a speed buffer.
The gust factor formula is also not recommended or supported in any of the light Cessna or Piper POH's that I have ever seen. The only mention of increasing speed I have found is in the Cessna POH. It notes that for
short field approaches
slightly higher approach speeds should be used in turbulent conditions.
For the Cessna 172 which is the airplane I referenced as an example in my original posts, the POH "Normal Operations" section gives a range of recommended approach speeds. They are 65 to 75 knots with no flap and 60 to 70 knots with 30 deg flaps. Therefore in my opinion this aircraft should never be flown at an approach airspeed faster than the upper range of the recommended values as they will provide a adequate margin above stall on all circumstances. If control at these upper range speeds feels doubtful then I would suggest that conditions are so extreme it is time to find another place to land.
I think it is also important to note that these speeds are for
gross weight. They will be to fast at lower weights. A pretty good rule of thumb is for a typical landing in a Cessna 172 or Piper Cherokee with 2 persons and half tanks reduce the gross weight approach speed by 5 knots. If you use the formula to adjust approach speeds you will find that the 5 knots reduction will pretty close to the calculated speeds for all your typical light fixed gear singles.
Watching landings my observations is that most landings I see are flown too fast resulting in excessive float and/or flat or even nose wheel first landings. Adding extra speed to the approach does not make it safer, in many case it increases the degree of difficulty and the likelihood of aircraft damage.