Workload during approach is very absorbing and great fun. Everything has been working really well so far for this newbie on final approach; IAS engaged at Target (say 123kts), flaps 25, APP engaged, aligned with the runway and on glideslope. But EGLC (London City) has a steep ILS descent - once clear of the financial district buildings. Suddenly it becomes clear that I'm above glideslope and trending higher. But throttles are already at flight idle. I've tried de-coupling the autopilot to regain glideslope by hand, but speed builds rapidly without enough loss of altitude, so I overshoot. What's the best way of dealing with this situation, whilst maintaining Target ? :( Many thanks!Best wishes,David Abrahams

David,If you're fully configured with gear down, flaps 25, and condition levers in FLIGHT, then there's nothing more you can do in order to create additional drag beyond slipping the airplane (and that's not an approved technique in the airline flying world).Also, airplanes that fly into London City have to be specially certified to fly the approach there, and I don't know if the J41 ever attained such certification. Anyone else know?Anyway, without additional drag, you'll have to accept an increase in airspeed if you want to maintain the steep glideslope. One way to do that might be to slow to Vref instead of Vt, and then start down. That will give you 15 extra knots of pad.Finally, you shouldn't be in IAS mode during any approach, because depending on your energy state, you'll wander off the glideslope as you've seen. Make sure you're in APR mode (Approach, not Automatic Power Reserve) so the AP will track the glideslope properly.

David,If you're fully configured with gear down, flaps 25, and condition levers in FLIGHT, then there's nothing more you can do in order to create additional drag beyond slipping the airplane (and that's not an approved technique in the airline flying world).

What about a less than full flap approach? I recall the discussions that the flaps have a great deal of lift, at least at 9. Maybe flying at 15 would help? Not sure how that would work in a bigger plane like this; I know in the singles that I fly, usually the last notch is a lot of drag and not a lot of lift. So, maybe an approach at 15 won't work either. Just musing.

Doug, I think the L/D ratio at 25 is less than 15 (i.e., flaps 25 has more lift but much more drag).The key to this scenario is starting the descent at a slower speed, it is easier to dissipate the excess energy in level flight so do it then. I notice the MD-11 does this automatically for arrivals with steep descents liket the ZIGGY at KONT. In the JS41, just use alt hold and slow to 200 KIAS before descending. The added benefit is you are getting a higher ft/nm descent slope at the lower speed thus lowering the required rate of descent.

Thanks to you, Nick, Doug and Dan for your thoughts!In response to Nick's open question about JS41 approval for EGLC: it is ...http://www.lcacc.org/aircraft/index.html#JetstreamYou'll notice that pilots' competence in executing 5.5 degree approaches is specifically mentioned. Well, that's clearly one dream job less on my list! :( The sim workaround of initiating the approach at Vref is intriguing - though given the obligation to maintain Target from FAF, maybe those guys just have to hand-fly the final approach, using the elevator pitch wheel to prevent speed build-up. That said, I can't believe the JS41 wouldn't have coupled ILS capability down to minimums for e.g. EGLC ... :( I'm going to give early-stage hand-flying a whirl and see where that ends up ... Best wishes,David Abrahams

...The sim workaround of initiating the approach at Vref is intriguing - ...

It is not a sim workaround (of course it should be vref + margin), but that is how you manage your energy in any airframe, whether it is a hang-glider, a 747 or a JS41. From physics 201, at any given time you have a certain amount of potential and kinetic energy (PE and KE). PE comes from gravity and is dependent on how high you are, KE comes from the square of how fast you are. PE is converted into KE (more speed) by reducing height and KE can be converted to PE by climbing. Engines increase KE and drag reduces it. To land, you need to get your PE to zero (touchdown) and KE to minimum (Vref). If you start at 10,000ft and 400knots, that is a lot of energy to loose and the only way to lose it is with drag. You can google the maths if you are interested but the important points are that drag is exponentially higher at higher airspeeds, and when KE is converted to PE and back again, energy is lost because of drag. The simple rule of thumb is slow down, then go down. Fly straight and level, reduce thrust and your airspeed will drop. When you are at Vapp, start your descent. If you want a steeper descent (such as EGLC) then you simply reduce your Vapp by the corresponding amount. The steepest descent that can be flown under control is when Vapp = Vref

It is not a sim workaround (of course it should be vref + margin), but that is how you manage your energy in any airframe, whether it is a hang-glider, a 747 or a JS41. From physics 201, at any given time you have a certain amount of potential and kinetic energy (PE and KE). PE comes from gravity and is dependent on how high you are, KE comes from the square of how fast you are. PE is converted into KE (more speed) by reducing height and KE can be converted to PE by climbing. Engines increase KE and drag reduces it. To land, you need to get your PE to zero (touchdown) and KE to minimum (Vref). If you start at 10,000ft and 400knots, that is a lot of energy to loose and the only way to lose it is with drag. You can google the maths if you are interested but the important points are that drag is exponentially higher at higher airspeeds, and when KE is converted to PE and back again, energy is lost because of drag. The simple rule of thumb is slow down, then go down. Fly straight and level, reduce thrust and your airspeed will drop. When you are at Vapp, start your descent. If you want a steeper descent (such as EGLC) then you simply reduce your Vapp by the corresponding amount. The steepest descent that can be flown under control is when Vapp = Vref

The sim (both FSX and FS9) do not simulate 'prop discing' at all. In the real world I can bomb into a circuit well above Vapp and when I need to slow down I put the props full fine. pull the power levers back and wipe my face off the windscreen :D You slow down quick quick like that in the B200. Off course we do not do that with self loading freight in the back. Really uncomfy for them :) On the empty legs though...I believe this effect is somewhat nullified by the geared prop on the J41 and airliners have spoilers that the pilot can use to slow down. FRED

Thanks very much for sharing your thoughts and experience, Fred and Paul.I really do understand the theory, but in practice, even starting the descent at Vref sometimes has my APR coupled descents at Flight Idle exceeding Target speed (by a a kt or two, but more than I expect) - and as for hitting Vref over the threshold, I've never yet managed it. On a nice long forgiving runway, fine, but on a short field like London City, I'm in the drink every time!! :( In short: do you and other experienced JS41 simmers always initiate coupled ILS descents at Vref or (alternatively) maintain "book" Vapp all the way down the glidepath and then round out to Vref in our (lovely) JS41? How do you achieve this - especially the roundout, without eating up half the runway?! :( (Maybe I should flick AP/APR off at 500ft, not 200ft, and use elevator pitch to slow down in time???)Thanks as always - and for your patience with me!Best wishes,David Abrahams

Remember converting from KE to PE and back costs energy, so if you find your self a few knots fast, dip the nose and drop low on the glide slope (Not below! just low), this will increase speed a few more knots, don't panic and don't rush, just let it stabalise, then pull the nose back up and watch the speed bleed off while you settle back on the glideslope. It takes a little practice but you get a real good feeling when you get it right.

David,I'm not familiar with the particulars of the LCY approach other than the fact that it's 5.5deg glideslope, but there are some basic concepts that are going to apply to any approach in the J41.Like Fred mentioned, airplanes with "free turbines" can control blade angle until the prop is said to be "discing" - the blades are in a flat pitch and generate no forward thrust, while the surface area of the prop disc contributes a significant amount of drag. The result is that it's much easier to control rate of descent and airspeed simultaneously.The J41 cannot do this due to the nature of the prop/engine design, and at Flight Idle still generates significant forward thrust. This means energy management, especially in the case of a steep approach like the one at LCY, is very important.

In short: do you and other experienced JS41 simmers always initiate coupled ILS descents at Vref or (alternatively) maintain "book" Vapp all the way down the glidepath and then round out to Vref in our (lovely) JS41? How do you achieve this - especially the roundout, without eating up half the runway?!

No, it's not common to fly a "normal" approach at Vref. I only suggested doing that because it appears that airspeed buildup during the 5.5deg approach is inevitable. Beginning the approach at Vref instead of Vt would give you an additional 15kt to play with, and results in you arriving over the threshold at Vt (Vref+15) instead of Vref+30. The latter being totally unmanageable.Approaches should always be flown at Vt regardless of method (coupled ILS, hand-flown raw data, visual, etc). At 200ft, airspeed should be allowed to decay in order to cross the threshold at Vref.

Maybe I should flick AP/APR off at 500ft, not 200ft, and use elevator pitch to slow down in time???

If you are on the glideslope when you initiate such a maneuver, you're going to end up excessively high (on an already steep glideslope), and you won't be in a position to make a safe landing in the touchdown zone. I don't know how it was/is done in the real world at LCY in a J41, but in the sim, I think the only way to arrive at the threshold on glideslope at Vref would be to start the approach with an excessively low (read: unsafe) airspeed.

Nick and Paul,These are really insightful, educational and helpful comments. Again, many thanks. Sounds like a sim JS41 approach into LCY calls for some eccentricity of technique which is probably not the best place to learn one's craft. Perhaps I'll practice another less demanding and more representative approach, so as to develop a feel for the basics of JS41 aerodynamics and control technique.Best wishes, David Abrahams

... more representative approach, so as to develop a feel for the basics of JS41 aerodynamics and control technique...

Sorry,I had assumed from the nature of your question that you already had the basics down pat and were looking for the subtle and fancy stuff. Ignore everything I have said until now and go fly the tutorial a couple of times until it feels relaxed with no rushing or surprises. Then hand fly the landings a few times, and with a little practice they will be as good as the AP touchdowns. After that, knowing that you can do it 'right' and that you can recognise and deal with unexpected stuff before it becomes a problem, you can try the deliberatly awkward stuff.

David,I decided to go fly the approach a few times to see what kind of results I would get. Here's what I found...I flew the first one as a coupled approach to 500ft, but the autopilot was a little late intercepting the GS so I was initially high, and the extra VS required to get back on the GS resulted in Vref+25 at flight idle. I was still able to manage speed in the flare, and with a little bit of float. I touched down firmly and in the touchdown zone. With spoilers, max reverse, and max braking I was able to make the Charlie turnoff.For the second aproach, I hand-flew the raw data ILS and found that with 20 pax and 900lb FOB, I was able to maintain Vt at idle all the way down the glideslope. I arrived at the flare carrying the extra 15 knots, but was able to bleed airspeed down to Vref during the flare. I landed in the TDZ and was still able to make the Charlie turnoff using spoilers, reverse, and only light/moderate braking.I was going to try a third approach, this time starting at Vref, but since I managed to get it stopped without trouble on the previous two attempts, I didn't bother.A few things for you to consider if you're ending up in the river: Are you flying the approach at significantly high/low gross weight? Are you floating excessively after the flare? Are you deviating excessively from the GS during the approach? Was your initial capture of the GS smooth and timely?Don't be afraid to plant it firmly if necessary. The sooner you get her down, the sooner you can get the boards out, get into reverse, and get on the brakes. Excessive float in order to be below Vref and/or attain a smooth touchdown isn't adviseable on short/wet runways.

Excessive float in order to be below Vref and/or attain a smooth touchdown isn't adviseable on short/wet runways

Floating is never a good idea, it also looks very amaturish to the hanger crowd that is always there watching when I botch a landing :(

Sorry,I had assumed from the nature of your question that you already had the basics down pat and were looking for the subtle and fancy stuff. Ignore everything I have said until now and go fly the tutorial a couple of times until it feels relaxed with no rushing or surprises. Then hand fly the landings a few times, and with a little practice they will be as good as the AP touchdowns. After that, knowing that you can do it 'right' and that you can recognise and deal with unexpected stuff before it becomes a problem, you can try the deliberatly awkward stuff.

Sound advice, Paul. I admit to flying a C172 in the real world these last 22 years, including the odd ILS, but definitely (and perhaps self-evidently) not a JS41 in any world for more than a couple of weeks! So it's off to White Plains again with humility and enthusiasm. I'll stay curious as to how real Jetstream pilots actually executed their approaches into LCY ... Best wishes,David Abrahams