Approach and Landing Speeds for Cessna 172
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Approach and Landing Speeds for Cessna 172
Has anyone got any thoughts on C172 landing speeds (surely this has come up before)?
The poh says 61KIAS for a short landing and '60 to 70' elsewhere. There is no direct reference to altering the speed for weight. Thus a student might fly the aircraft solo using a threshold speed of 65 and then pick up 400lbs of extra pax and go flying using the same speeds. No great harm is likely to result but is there any formal teaching in circulation? Conversely, a student may fly with a full load all year, using speeds towards to top of the range and then book in for a few circuits solo prior to a test and come over the hedge horribly fast for the weight. Over-flares, ballooned landings, PIOs etc are, in my experience, quite common in these circumstances. Anyone got anything useful to say? (for 'student' read 'low time ppl'. C172P with standard tanks and 30 flap.
The poh says 61KIAS for a short landing and '60 to 70' elsewhere. There is no direct reference to altering the speed for weight. Thus a student might fly the aircraft solo using a threshold speed of 65 and then pick up 400lbs of extra pax and go flying using the same speeds. No great harm is likely to result but is there any formal teaching in circulation? Conversely, a student may fly with a full load all year, using speeds towards to top of the range and then book in for a few circuits solo prior to a test and come over the hedge horribly fast for the weight. Over-flares, ballooned landings, PIOs etc are, in my experience, quite common in these circumstances. Anyone got anything useful to say? (for 'student' read 'low time ppl'. C172P with standard tanks and 30 flap.
All speeds are based on the maximum AUW so if you were going to do anything you would be looking at reduced speeds for lower weights. 70 is to fast and wil lead to floating down the runway. If you fly 70 Kts pror to taking full flap, the speed will reduce to 65 on application of the final stage of flap.
I recall landing one in a spot landing competition where I touched down at 45 kts, the ASI will underead at the AOA involved and I don't recall the stall warner even bleeping once.
I recall landing one in a spot landing competition where I touched down at 45 kts, the ASI will underead at the AOA involved and I don't recall the stall warner even bleeping once.
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Bottom line, speeds aren't that critical in light aircraft, as opposed to heavier stuff. The waffly range of landing speeds in the typical POH is annoying but most PPLs should have received enough training to realise higher weight = higher speed.
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Eckhard.
Just to clarify. If there is, say, a speed range of 60-70 quoted in the POH, then 60 is for minimal weight and 70 for maximum landing weight. I agree with what you say about excessive speed 100%.
Just to clarify. If there is, say, a speed range of 60-70 quoted in the POH, then 60 is for minimal weight and 70 for maximum landing weight. I agree with what you say about excessive speed 100%.
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.
These are threshold speeds of course, touchdown will be at a lower speed but I cannot give you a reliable figure for that, seeing how many different variations you can get in the flare. Your eyes (or those of the student) should be elsewhere at that point anyway.
These are threshold speeds of course, touchdown will be at a lower speed but I cannot give you a reliable figure for that, seeing how many different variations you can get in the flare. Your eyes (or those of the student) should be elsewhere at that point anyway.
Last edited by Jhieminga; 11th Oct 2017 at 12:38. Reason: added a bit...
Don't be fooled on the term short field. The tables give you ground roll and total to clear a 50 feet obstacle on approach. The Cessna Information Manual 1980 for Model 172N gives 59 knots at 50 feet for landing. That is ample speed and will give you a comfortable float before touch down. That is power on or power at idle for the final approach. A "normal landing approach" with Flaps at 40 degrees gives you a range of speeds 55 knots to 65 knots. And 55 knots is less than the "short field" of 59 knots so try and make sense of that.
59 knots over the fence with full flap is safe as houses and although associated with the terminology "short field", is the airspeed you should use for everyday landings. With airliners the performance charts give you landing distance required and the airspeed at 50 feet. That is the equivalent of the tables marked "Short Field" in the C172 manufacturer's Information Manual. Also note with the C172N there is only five knots difference in the landing speeds between 40 degrees of flap and flaps up. Bit different on the Boeing 737 where the difference is around 50 knots.
Long floats caused by excessive threshold speed are to be avoided as they can lead to a bounced touch-down caused by a pilot trying to "spike" the aircraft nose-wheel first on to the runway and the potential for nose-wheel collapse.
59 knots over the fence with full flap is safe as houses and although associated with the terminology "short field", is the airspeed you should use for everyday landings. With airliners the performance charts give you landing distance required and the airspeed at 50 feet. That is the equivalent of the tables marked "Short Field" in the C172 manufacturer's Information Manual. Also note with the C172N there is only five knots difference in the landing speeds between 40 degrees of flap and flaps up. Bit different on the Boeing 737 where the difference is around 50 knots.
Long floats caused by excessive threshold speed are to be avoided as they can lead to a bounced touch-down caused by a pilot trying to "spike" the aircraft nose-wheel first on to the runway and the potential for nose-wheel collapse.
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.
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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
I would have thought thatyou would have to lose 15 kts between threshold & touchdown in your example!
Bill
Bill
Yes a typo on my part. The point remains very valid though.....
I completely agree with your point, BPF, but I was basing my advice on the fact that quite a few students are not all that familiar with using CAS instead of IAS. For a 172R the stall speed at max gross is 47KCAS for flaps 30 but this is equivalent to 33KIAS. If a student takes up the advice to use 1.3xVs and he would base this on indicated speeds, he would then creep over the hedge at 44KIAS, admittedly that equates to a CAS that is a shade higher (approx. 50KCAS), but still too low for my comfort.
I have trained a lot of students on 172s using 65KIAS on final and haven't had all that many issues with that. I agree that a lower speed is certainly an option and have regularly flown approaches down to 50-55KIAS myself, but it is not something I would start with for a student.
I have trained a lot of students on 172s using 65KIAS on final and haven't had all that many issues with that. I agree that a lower speed is certainly an option and have regularly flown approaches down to 50-55KIAS myself, but it is not something I would start with for a student.
