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Bouncy/Porpoise Landings

I imagine ATC already factors in the fact that you are going to slow down in these last few miles. Ending up going faster than their expectations probably doesn’t benefit them in any practical way (unless they know you’ll always do that and factor you in differently).

Ibra wrote:

Ground speed or on the ASI?

I guess there is a difference between 1/ arriving at higher speed then bleeding it all completely off before touchdown versus 2/ touchdown at higher GS airspeed

You do the first one, if you enjoy a quick landing with low power on long runways (length of the runway is included in the landing fee ), especially when you have 20kts of head-winds

However, I really don’t see the point doing the later unless you are forced by other factors (e.g. too much cross-wind/gusts on narrow runway, tail-wheeler if you can’t judge 3 points or like to see ahead…), but even for those reasons you will probably need to think twice if your GS is higher

Mainly on the ASI. In EDWF, where I did my PPL, you often faced strong headwinds or at least gusts on RWY26. Especially if you touched down on the first half of the runway due to adjacent trees. Local practice was to land on the second half of the 1200m runway whenever it was windy, especially with crosswords. Over the first half one would keep the speed up to about 70 kts indicated because sudden gusts could always steal you 10-15 kts any time.

We also did a few landings with 70 kts ground speed but I agree with you that that serves little purpose.

Low-hours pilot
EDVM Hildesheim, Germany

If there is a reason to “keep the speed up” until late in the approach, plan to sideslip off the speed when the time is right. Flaps are great, but the sideslip seems to be a forgotten tool for speed control. I practice slipped approaches regularly, holding in full rudder deflection for an extended period, and modulating ailerons for directional control. Before someone points out that 172’s can’t be slipped – they can. Some models are better slipped with the flaps retracted, a few of the earlier models must be slipped with a little extra caution if the flaps have been extended much. For speed management, fly the faster approach, slip off the speed when you’re ready, and then apply the landing flap late in the approach. This take a little timing and practice, but then anything in flying does!

Home runway, in central Ontario, Canada, Canada

MedEwok wrote:

Over the first half one would keep the speed up to about 70 kts indicated because sudden gusts could always steal you 10-15 kts any time.

Yes, with gusts the best is be very steep and too fast (you may see ASI drops up to 1/2 of the gust), if you fly shallow & fast, then a big ASI drop will get you “stuck behind the drag curve with lot of sink”, even full power may not help you out, the only way to get way with it is by pushing the stick forward but you are not high neither plus hit a gust in the first place because you skimmed the trees tops

If you come steep & fast with no wind-sheer or gust is around, you may look like super-man flying but on the plus side a go-around looks very obvious even before flaring, so a win-win

Pilot_DAR wrote:

Before someone points out that 172’s can’t be slipped – they can.

I believe that was a limitation on 40 degrees flapped ones following a “news headline accident” otherwise one should always side-slip one or two degrees all the time just in case you want it when you flare and you start drifting with cross-wind (making sure you have the controls crossed in the right way in the critical moment)

Side-slipping is good quick adjustment mechanism, for flaps I am not sure? I always get surprised by their ballon/sink when flying low but probably I should learn to use and adjust to them better? in my view I always get them settled long time ago and not to fiddle with them close to the ground (or gear? or air-breaks?), my order of priority was always: flaps, power, air-break, side-slip, stick… but others may have their own taste

I flew a TMG that has all of the 5, on downwind, you have to decide you are either a glider pilot or power pilot? whether you like to be a glider pilot who go-around? and which control come first rather than mixing all of them in the heat of the moment

Last Edited by Ibra at 12 Oct 12:20
Paris/Essex, France/UK, United Kingdom

Pilot_DAR wrote:

If there is a reason to “keep the speed up” until late in the approach, plan to sideslip off the speed when the time is right. Flaps are great, but the sideslip seems to be a forgotten tool for speed control.

Slideslips work well for that purpose, but pax don’t like it!

ESKC (Uppsala/Sundbro), Sweden

Ibra wrote:

I believe that was a limitation on 40 degrees flapped ones

There was never a limitation on sideslips on C172s, but there was (and is) a note in the POH that sideslips with flaps extended should be avoided. But there is seldom any reason to sideslip a C172 on approach — the flaps are quite effective brakes.

ESKC (Uppsala/Sundbro), Sweden

Does being so fast really help?

Quick back of the envelope calculation for a runway that has a mile after the touchdown point, wherever you choose to put it:

  • Fly two mile final at 60kt, land, take turn-off at 500m. Time taken: 2 minutes until touchdown, maybe 0:30 to vacate → 2:30
  • Fly two mile final at 90kt, fly 1,300m along the runway bleeding off speed, vacate at the end. Time taken: 1:20 to original TD point, 0:40 to fly along runway, 0:30 to vacate.

Total difference: nothing. maybe a few seconds. Of course there are scenarios where that saves a few seconds, but It probably matters more to touch down at a sensible point to minimise runway occupancy. Combine that with the risk of running of the end —> not worth it.

Of course it is good airmanship to fly in a way that helps others out, including those on a faster approach behind you, but bleeding off speed should happen before you cross the threshold, and should not require unusual manoeuvres. Of course what is unusual depends on what you usually do, but 50ft above ground is a bad place to fly your first sideslip in five years.

Biggin Hill

With no parallel taxiway, that approach was planned for a quick exit at slow speed. ATC phrase was " Can you keep it tight?" Not an uncommon approach, for me, at my homebase.
In an SEP, a very safe approach in case of an engine failure.

Maoraigh
EGPE, United Kingdom

I trained fast approach for 3 reasons only:

  • High cross-wind. The runway at my home base is positined almost 90 degree to the dominant wind.
  • To demonstrate how much more runway you consume dumping all the excess speed, and how much work it is keeping the plane on the centerline for all that time, with said crosswind. The conclusion of the exercise was “don’t do it”.
  • Flap failure / disymetric flap. I actually got that one at my checkride.
ESMK, Sweden

Airborne_Again wrote:

But there is seldom any reason to sideslip a C172 on approach — the flaps are quite effective brakes.

The flaps on a 172 create both drag and lift. Yes, they will act as brakes, and while doing that, create more lift, particularly if you’re carrying extra speed. It’s no wonder that 172’s are labeled as “floating” planes, ‘cause pilots keep approaching too fast, and then wondering why it does not want to land! A sideslip is a drag only maneuver, and instantly recoverable. Drag, no drag, drag again, if you need to modulate. Yes, if you have to do that onto a longish runway, you’ve probably botched the approach, and should be re-evaluating your technique. However, there is a whole other world of approaches, some emergency, where different techniques are beneficial.

When I train forced approaches, I will set up the scenario with the suitable landing area being too close. Slipping (sometimes in a spiral), and later use of flaps, will get you in. Slipping the forced approach into a nearer landing area will prevent the attempt to stretch a glide, and then undershoot. I teach that you’re better to go off the far end of the landing area at a decelerating slow speed, than to undershoot, and hit whatever the approach obstacle is at flying (or stalling) speed. This is of particular importance for a forced approach on skis or floats, where the approach path will most likely not be that of an airport or “nice field” environment. You may have to get in over a hill, or stand of trees, tucked in right behind, or tight to shore. The key is to be proficient in using all the flying skills, and in the proper order. A slipped forced approach can be unslipped to extend a mis judged glide. Once the flaps are extended, you’ve really committed yourself to that approach path, ‘cause you’re not going to stretch it much from that!

Yes, flaps fail, I’ve had it happen three times, once with manual flaps in a C180 – jammed at 20, won’t go up or down! I had to takeoff that way, fly it home, and land again.

It’s true that pax may not like being slipped, so yes, consider that. But that is not an excuse for a pilot to not be proficient at it, practice with no, or understanding pax. Ultimately, your pax would rather feel uneasy as they step out of the plane because you slipped it in, than being cut out of the plane because you didn’t.

Home runway, in central Ontario, Canada, Canada
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