Originally Posted by
Jhieminga
Using 1.3xVstall is not very handy in a Cessna as the stall speed will be so low that you end up creeping towards the threshold with barely any margin in case of gusts. It can be done, but expect to end up at the low (unreliable) end of the ASI. In my experience using 65kt with flaps 30 works on the various 172s that I've flown, with the odd adjustment to 70 in case of severe gusts. For a student I would use this as a basis and brief them on the possibility of adjusting this speed based on loading.
.
I think you need to review the POH. First for the C 172 Indicated Airspeed is always equal to or
lower than Calibrated Airspeed. For example ( C172 P ) flaps up 50 kt IAS is 56 Calibrated, so at the low range you will being going faster than the number on the ASI.
The flaps 30 Calibrated speed at an indicated 55 is 57 kts. the Calibrated stall speed is 46. Flying an approach at 55 IAS will result in a 1.25 VSO margin at gross weight. At a more typical training weight you are right at 1.3 VSO. On any reasonably smooth day this is totally safe and easy to do.
I think the under lying issue is that there seems to be a climate of fear in the flight schools that students may get too slow and stall on final approach. This has resulted in the illusion that requiring high approach speeds is makes things " safer".
In fact the the opposite occurs. From my observations on average at the moment of touchdown in the proper tail low touch landing attitude the airspeed will be around 55 kts. So if the threshold crossing speed is 70 then you will have to lose
25kts between crossing the threshold and touching down. This will inevitably result in excessive float and greatly increase the probability of a nose wheel first landing
From what I have observed at my home airport most landings are 3 point or nose wheel first, often with a bounce of the nose wheel. This has resulted in an epidemic of busted firewalls. Virtually every training airplane has had to have firewall repairs due to nose wheel first hits on landing. The excessive speed results in excessive float which makes it harder for new pilots to transition from the flare to the proper tail low touchdown attitude without ballooning or hitting on all 3 wheels at the same time.
When a low time PPL asks me for advice on landing the first thing I tell him is to reduce his approach speed by 5 kts. It is amazing how many times I have heard back that his landings instantly got better
My advice to all instructors is to go and practice 55 kt approaches. A surprising number of the ones I know have never done one. You will find that
they are very easy and it will help dispel the myth about how dangerous getting slow on approach is.
FWIW this is what I teach
Normal landings flap 20 65 kt
Short field flap 30 60 kt
Cross wind flap 10 65 kt