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NeilC

Steeper descent profile

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Hi Guys,

I am fairly new to the DC-6 (having cut my teeth on the MD-83 for the past 15 years).

I am quite familiar with constant speed props, but am really struggling to get the DC6 to descend.  I have read that you need to plan well ahead and start descent early, but I am having real problems slowing down.  When using the AFE, having completed the inrange checks, you need to slow down far enough to be able to drop the flaps as part of the final check.  I have also read elsewhere that you shouldn't go below a BMEP of 80 (and of course you should avoid the props driving the engine at all times), but at the lowest possible settings in level flight, the speed bleeds off so slowly.

Most of my flying is around the mountains of Austria and Switzerland and I am finding it impossible to fly certain approaches, as I just can't lose the height necessary.  I know that the DC6 wasn't built with steep approaches in mind, but they have operated into airports such as LOWI, so it must be possible.

Also, on final (inside the inner marker 4/DME) is it permissible to go below 80 BMEP?

Sorry for all these questions, I am loving the DC6, and would like to do it right.

Neil 

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6 hours ago, NeilC said:

Hi Guys,

I am fairly new to the DC-6 (having cut my teeth on the MD-83 for the past 15 years).

I am quite familiar with constant speed props, but am really struggling to get the DC6 to descend.  I have read that you need to plan well ahead and start descent early, but I am having real problems slowing down.  When using the AFE, having completed the inrange checks, you need to slow down far enough to be able to drop the flaps as part of the final check.  I have also read elsewhere that you shouldn't go below a BMEP of 80 (and of course you should avoid the props driving the engine at all times), but at the lowest possible settings in level flight, the speed bleeds off so slowly.

Most of my flying is around the mountains of Austria and Switzerland and I am finding it impossible to fly certain approaches, as I just can't lose the height necessary.  I know that the DC6 wasn't built with steep approaches in mind, but they have operated into airports such as LOWI, so it must be possible.

Also, on final (inside the inner marker 4/DME) is it permissible to go below 80 BMEP?

Sorry for all these questions, I am loving the DC6, and would like to do it right.

Neil 

Hi Neil, please note that PMDG asks that we use our full name on all posts in their forums.

You are correct, the descent requires planning.  I usually descent using the MP gauge (in my opinion any positive BMEP means the props are not driving the engine, not sure where 80 comes from).  I plan for a 500 fpm descent at about the same or slightly higher speed that I am cruising.  This is achieved by reducing power to 25 inHg, and leaving the props alone or increasing to 2200 RPM.  The key piece of information is distance required, and that depends a lot on your ground speed.  If you have DME or GPS use it to get a cruise groundspeed and use that for the descent planning.... true the groundspeed will decrease for a give airspeed as you descend the your airspeed is likely to increase thus offsetting the decrease.  We just want to be close, exact is not necessary.  So 240 kt GS is (240/60) about 4 nm/min and a descent of 500 ft/min means every 1000 ft of descent will require about 8 nm.  If you are at 8000 and want to descend to 2000 you need to start down at least (6 x 8 ) 42 nm before airport and maybe a little more for a straight in approach.  The secret to speed control is to level off at the 2000 ft AGL point and bleed speed there, you only need to bleed off enough to start the flap sequence... once there are flaps out you get dirty and slow down easily.  Alternatively, you can slow down before you go down, this method works great if you need to shorten the distance for the descent.

A steep approach is exactly what you get will full flaps, I normally do not put out that last notch of flap until I am over the fence or approach lights.  Yes, during approach you can reduce BMEP to any positive number.  Unless you were too fast, those barn door flaps are going to need some power on to keep from falling out of the sky anyway.

Try flying without the AFE.  I only used that feature once during beta testing.... I understand it's usefulness and utility but there really isn't a need for it in a simulator in my opinion.  Doing the work yourself will build your confidence in being able to handle this beautiful machine.

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Thanks for the reply.

I do put the AFE into hold and set the props/engines myself a lot of the time.  I am just struggling with losing height quickly.  I suppose if I need to descend into a valley from above mountain peak altitude, I need to configure to full flaps and then descend.  To do this I need to reduce the engines down manually to lose the speed, but had read that a BMEP bellow 80 was not used in the real world.  Flying variable pitch I normally stick to the rule that the manifold pressure is above the prop speed it should be ok.

Thanks again,

Neil

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2 hours ago, NeilC said:

Thanks for the reply.

I do put the AFE into hold and set the props/engines myself a lot of the time.  I am just struggling with losing height quickly.  I suppose if I need to descend into a valley from above mountain peak altitude, I need to configure to full flaps and then descend.  To do this I need to reduce the engines down manually to lose the speed, but had read that a BMEP bellow 80 was not used in the real world.  Flying variable pitch I normally stick to the rule that the manifold pressure is above the prop speed it should be ok.

Thanks again,

Neil

I think you are on the right track as far as your logic goes.  I'm not sure about the BMEP >80 being a thing, maybe just a suggestion but by definition any positive BMEP number means the prop is not turning the engines.  I do try to keep the MP at 25 inHg in a normal descent, and any lower than 22 inHg (I think) you get a gear horn so there are practical limits.  The shock cooling concern for these engines isn't a normal concern but one does avoid a rapid cool down.  The descend into a valley is best done using the adage "go slow or go down."  In other words you cannot do both, only one or the other so you might want to reduce speed to 190 drop 10 deg of flaps and descent at 2200/25.  If you are going into a well you could drop gear.  Watch your CHTs and do the slow down at altitude in 2 inHg steps of MP slowly decreasing to decrease CHT on a ramp rather than a step.  Other than descending into a valley (I've done this at Lake Tahoe CA) this procedure is not a "normal" procedure.

Edited by downscc

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Hi!

I also had some troubles, but I've found some tricks to fly into airports around central europe:

1. Look out for alternative STARs, maybe search for a route around your destination and approach it from the other side where you maybe won't need steep angles.

2. Decrease your airspeed/power before you start your descent, this will prevent an IAS of 200+ KIAS, so that you just need about 10nm of level flight to slow down to the magical 174 KIAS to lower gears/flaps.

3. If required, I slow down to 170 KIAS and drop the gear before starting the desent. The DC-7 actually had an "airbrake" lever, which dropped the main landing gears to achieve steeper descend angles (apparently they learned something from the DC-6).

4. If you see that you won't make the required altitude and speed in time, ask ATC for a hold before the FAF. It's easier and much less annoying to fly some holding patterns for descending and slowing down than to make a go-around or even crash the plane by forcing it onto the ground.

Edited by TheFinn88

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A little addendum to my post after my yesterdays flight into KMDW. The MOTIF6 STAR requires to cross MOTIF at 10'000ft and the next waypoint MINOK at 6'000ft, with just 15.6 nautical miles between them. For this STAR I slowed down to 170 KIAS and dropped my flaps to 10° before starting the descend from 13'000ft to 10'000ft between the BDF VOR and MOTIF. Just right before MOTIF I reduced my airspeed to 160 KIAS and dropped my flaps to 20°. In this configuration I was able to achieve a descend rate of about 800 feet per minute while keeping 160 KIAS.

With an airspeed of 160 knots you need about 5.8 minutes to cover these 15.6 nautical miles, while you have to descend 4000 feet. At a rate of 800 feet per minute, you'll require 5 minutes to descend from 10'000ft to 6000ft. So this can be done, but only with a good descend planning and some drag extended. When you would try to fly the MOTIF6 arrival in clean configuration, you won't be able to comply with the altitude restirctions. With an airspeed of about 180 KIAS at 0° flaps and a descend rate of about 500 feet per minute, you would require 8 minutes to descend from 10'000ft to 6'000ft while you would reach MINOK after just 5.2 minutes.

Maybe with additional drag by also extending the landing gear, you are able to achieve an even greater rate of descend. I havn't tried this yet. Also I was quite light at a gross-weight of just 73'000 lbs. Don't know how the six would perform heavily loaded. :rolleyes: And in a controlled airspace (I always fly on IVAO), the ATC probably would vector you on a different route to get you out of the way for faster planes.

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9 hours ago, TheFinn88 said:

The MOTIF6 STAR

It is highly unlikely ATC would give this arrival in a clearance to a DC6.  This aircraft can be flown above the TA (18000) but if you look at the performance charts you might notice that there is no reason to do so.  I recommend that flights be planned with cruise altitudes between 8500 -17500 and go VFR if weather and terrain permitting.  You will find a few terminal procedures for low and slow at places like LAX, DFW or IAH and surrounding airports, but if the procedure is for turbojets or turboprops then you need to assume its not for the DC6.  Besides, it's a lot more fun to fly VFR in this beautiful aircraft.

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I was cruising at 15'000ft, so it was in the range what you call a normal cruising altitude. And turboprops flying the CVA.MOTIF 6 arrival at KMDW are expected to cross DIPSY (the first altitude restriction on this route) at 13'000ft (jets at 15'000ft). So I don't see any troubles in flying that STAR with the DC-6 too. Sure ATC might have vectored me on a different route (as I've already written in my earlier post), but there was none online, in such a case I stick to a STAR that the DC-6 is able to comply with. There are loads of STAR's that have altitude restrictions above 20'000ft (e.g. the ENDEE 4 arrival at KMDW that starts at FL240 up to FL330), some airports have alternative STARs with lower altitide restrictions, and some airports don't. In such a case I take a look at the approach charts and search for the IAFs. Some of them have a VOR near to them (or the VOR might even be the IAF), and I'll pick that as my last waypoint of my route. But if there is a STAR like the CVA.MOTIF 6, I at least try to fly it.

Flying VFR is fine, but I would like to see you flying the VFR approach routes for LSZH with the DC-6, which are solely meant for small aircraft! :biggrin: Even if you could comply with them, your PAX would be screaming in the back. :laugh: I always wondered how big aircraft fly VFR in and out of a controlled airport? Lets take LSZH again, it has published visual approach routes and waypoints, but they are really only meant for small single or twin engine piston aircraft (and maybe the JU-52), and it has pretty small holding patterns (with a speed restriction of 90 knots) and quite sharp turns which in my opinion the DC-6 can't handle because she's flying much faster. But the Red Bull DC-6 has already been many times at LSZH, and I suppose that they flew VFR. But how is it handled? Are they vectored by ATC in and out of the CTR when they can't stick to the visual departure and arrival routes? Or do they get special clearances, e.g. to fly direct to the visual departure waypoint by ignoring the published routes?

This is one reason why I mostly fly IFR, because I really don't know how a DC-6 is flown VFR in todays controlled airspace as most of the published routes are meant for small aircraft only. And the other reason is because I'm flying in real time and on evenings, it's mostly getting night before I get to my destination (especially during the winter)... And Switzerland doesn't permit night VFR flights (only on some occasions during the summer).

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8 hours ago, TheFinn88 said:

But the Red Bull DC-6 has already been many times at LSZH, and I suppose that they flew VFR. But how is it handled? Are they vectored by ATC in and out of the CTR when they can't stick to the visual departure and arrival routes? Or do they get special clearances, e.g. to fly direct to the visual departure waypoint by ignoring the published routes?

One of the PMDG DC6 technical team members is a pilot on the Red Bull aircraft so maybe he will chime in if he's lurking.  I'm not familiar with European flight operations but I'm not surprised there is very little VFR in an area so small with so much traffic and highly regulated.  My VFR comments were following your post regarding a MDW arrival, where you will find substantial VFR traffic within the confines of the Class B airspace.   Back to Europe: I am certain that the DC6 is not going to be treated the same as a turboprop commuter, and that flight safety will be ensured so I'd say yes to a combination of vectors and clearances that are suitable for this aircraft.  The main point is that you cannot shoe horn this airplane into a set of terminal procedures created for modern aircraft.

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On ‎8‎/‎9‎/‎2018 at 1:45 AM, TheFinn88 said:

 And in a controlled airspace (I always fly on IVAO), the ATC probably would vector you on a different route to get you out of the way for faster planes.

In the real world if I couldn't make a speed or crossing restriction, I've told ATC and they have always worked with me.  Where the problem comes is not telling ATC.  🙂

All the crossing and speed restrictions that are on SIDS/STARS/HOLDING are to make ATC's life easier and can be changed by ATC if and when necessary.

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I can only talk about my RW flights on the DC-3, which has a similar descent profile. They key is in the diagram on an approach and you will see there that you slow down in the pattern early and use flaps and gear to accomodadate to descending. You can basically fly any VFR pattern used for larger GA aircraft like a Piper Chieftain.

Here is an extract from my DC-6 Flying Guide:

A good pattern speed with 20° flaps configuration would typically be 125 kts (Vref+35) for downwind and 105 kts (Vref+15) for base leg which you get by setting flaps to 30°. The engine settings are then similar to what you used during a shallow descent making it easy not to change engine setting too much. Best practice is in fact to keep the engines in a small window around 30 in for level flight down to 25 in during a descent with RPM at 2000. When you turn on final you drop the gear and increase RPM to 2300 1/min. Again vary MAP between 28 in for flaps 20° and 30 to 32 in for flaps 40 to 50° for matching final approach speed. Therefore, speed management during approach and landing should be managed by adding drag from lowering flaps and gear and not changing engine setting beyond those small adjustments.

Now when approaching larger airports like Zürich or Geneva in the DC-3, we use the VFR entry points or may get radar vectors to be established on the approach 3 miles out so that we can fly a 3° descent with 500 ft/min at 100 kts. We always need to remind the tower that we have an 80 kts final speed and that they need to keep enough space behind us. Also that they can alow aircrafts departing longer as we come in sooo slow. In the beginning of the DC-3 times in GVA , I have see two go arounds behind us and 5 planes at the holding points. Now all tower ATC know us well.

Not much difference for the Connie or the DC-6. Everything just 15 kts faster.

Now for the steep approach into Innsbruck via RTT and the LOC DME 08/26 EAST, you can only fly those 3.77° angle descent  with flaps 40° and gear down.

I have not come across an 80 BMP minimum. The important rule is to have MP equal or slightly above RPM/100. 

As for DC-3 or Connie descnt planning we are using only 300 ft/min, so you need to start out early from your destination.

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Thanks, 

This is really great info.  I was flying around this morning in Manfred Jahn's fantastic DC3, and came in a bit hot and high, and just could not lose the speed enough to get below 100kts and drop 1/2 flaps.  I was running 1700rpm and 17 MP, and it still would not bleed off (I ended up doing an orbit on 3 mile final (something which VLM F50s used to do at the airport where I control - EGLC - but was then outlawed by the CAA).

At what stage is it acceptable to reduce MP below RPM?  Only as you flare, or on final as well?

I am obviously treating the DC3/6 too much like a modern GA twin.

Thanks again for the info.

Neil

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6 hours ago, NeilC said:

At what stage is it acceptable to reduce MP below RPM?  Only as you flare, or on final as well?

Once the gear are down you should not need to reduce power by that much, the drag from flaps and gear will normally require a reasonable power setting.  If you are steep (3.77 is steep but I've flown 6 deg into Aspin) you need to get all the barn doors open (Flaps 40) and just keep a positive BMEP... you should need some power to keep from sinking like a rock.  Don't worry about MP at this stage, the positive BMEP assures you are not windmilling.

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What about the DC-3. No BMEP gauges, so should/must you always keep MP above RPM, even on final if trying to slow (I appreciate that it is probably bad planning leading to all of this, but is it allowed?)

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2 hours ago, NeilC said:

What about the DC-3. No BMEP gauges, so should/must you always keep MP above RPM, even on final if trying to slow (I appreciate that it is probably bad planning leading to all of this, but is it allowed?)

Keep it simple... the whole issue is because there is a reduction gear and it's designed to apply thrust.  You get into trouble when the propeller drives the engine which creates negative torque.  As long as you don't "windmill" the engine you are good.

On more modern light GA twins, other than the geared C-421 and other similar geared engines, the power during descent is to prevent cooling the heads too quickly.  This is not an issue with these large radials.

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I had another go in the DC-3 (I appreciate this is the DC-6 forum, but I love both), and with a light load, full flaps, gear down, props at landing setting of about 2400rpm, if I kept the MP above 24 I could not descend (in fact, it was accelerating a little in level flight).

What am I doing wrong? If I reduce MP to about 20, it flies fine on final, but then the props are windmilling!

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10 hours ago, NeilC said:

If I reduce MP to about 20, it flies fine on final, but then the props are windmilling!

How do you know that they are windmilling the engine?  I've got no experience with DC3 but it's normal to see 20 inHg MP in the DC6 on final. 

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I thought that if the MP is less than the RPM, you are driving the engines. So with the RPM at 2400 on final, a MP of 20 would not be ideal. Have I got this wrong?

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4 minutes ago, NeilC said:

I thought that if the MP is less than the RPM, you are driving the engines

That is something you can test for yourself in the DC6.   You are still pulling about 80 in of BMEP with 20/2400 I think... it's been more than a few days and my memory...

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12 minutes ago, NeilC said:

I thought that if the MP is less than the RPM, you are driving the engines. So with the RPM at 2400 on final, a MP of 20 would not be ideal. Have I got this wrong?

Dan is certainly more qualified than I to comment on the nature of constant-speed piston props (and of course when it comes to the DC6/DC3 we're talking radials so even further outside of my knowledge areas!) but I would say that in general it is difficult, if not impossible, to make any connection between manifold pressure and engine torque.

Manifold pressure is simply a measure of the pressure in the intake. When the engines are shut down on the ground, the manifold pressure will be circa 30 inches... engine torque output, zero. Indeed, the general advice (albeit arguably an old wives tale for precisely the same reason) traditionally, at least with naturally aspirated piston engines (although, not radials specifically) was that one should avoid operating "over square" - i.e. with manifold pressure > RPM.

Without a torque gauge I can't think of any reliable way to determine whether negative torque is being generated, but I'm happy to learn otherwise!

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14 hours ago, skelsey said:

Dan is certainly more qualified than I to comment on the nature of constant-speed piston props (and of course when it comes to the DC6/DC3 we're talking radials so even further outside of my knowledge areas!) but I would say that in general it is difficult, if not impossible, to make any connection between manifold pressure and engine torque.

Manifold pressure is simply a measure of the pressure in the intake. When the engines are shut down on the ground, the manifold pressure will be circa 30 inches... engine torque output, zero. Indeed, the general advice (albeit arguably an old wives tale for precisely the same reason) traditionally, at least with naturally aspirated piston engines (although, not radials specifically) was that one should avoid operating "over square" - i.e. with manifold pressure > RPM.

Manifold pressure in a supercharged or turbocharged engine is actually a very good indication of the power that the engine will produce.

The relationship between manifold pressure and rpm will depend on the engine design so I agree that a rule of thumb relating the two can surely only apply to one engine or family of similar engines. 

Edited by kevinh

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Neil, remember you need your first and last name in the PMDG support forum 🙂

 

Hi guys, just thought I would add my thoughts on this topic,

For some background: I have been flying high performance propliners for a while in FSX, using the wonderful freeware aircraft and handling techniques available at California Classic Propliners

To get the best experience from aircraft such as the wonderful PMDG DC-6B, I recommend reading (and practicing) all of the wonderful 2008 Propliner Tutorial. There are a lot of misconceptions that can be answered by this document, but be warned it is very thorough (read: lengthy)! In fact I use the "handling notes" of the freeware Tom Gibson/FSAviator DC-6B CB16 to provide for easy handling of the PMDG version (supplemented by the provided PMDG charts).

The 2008 Propliner tutorial explains what I believe is the fundamental error Neil is making regarding his DC-6 handling (as I too know from personal experience).

Quote

Most flight simulation users fail to plan TOD correctly, fail to vacate cruise at TIME = TOD, and then fail to manage their energy state competently after their mistaken TOD. Consequently most flight simulation users soon loose control of drag altogether, because they descend too late, too steeply, and with too much power applied.

Neil, I believe your problems fundamentally state from a late descent from cruise altitude which result in you carrying way too much speed on approach, likely combined with incorrect power settings which result in you being unable to meet the targets of a charted instrument approach. The humble CalClassic page gives a great deal of information on how to handle these demanding aircraft, and I will only give a very quick (IMHO) tips and suggestions for the thread. The goal of my post is only to give a very quick overview of the problems and concepts in this thread as I see them.

1) Neil, you need to start a descent MUCH MUCH earlier than you would expect to in a turbine aircraft (prop or jet). Plan and execute a 500FPM descent all the way down from cruise altitude to the IAF.

2) The recommended configuration of a DC-6B CB16 when you cross the IAF (at the lowest legal altitude) is as follows.

Quote

COWL FLAPS = 1 degree

2000 RPM

MINIMUM 20 INCHES MAP

FLAP = STAGE 2

MAINTAIN 140 KIAS

with these targets in place, at less than MGLW, the DC-6 (PMDG or freeware) has no problem descending on the overwhelming majority of IAP's in the world, despite mountains or other obstacles. This aircraft is designed for those approaches, and those approaches are designed to be flown by this type of aircraft.

3) Full IAP's flown in the PMDG DC-6B are certainly possible by following the MAP>(RPM/100) operating restriction. I find the justification for this restriction compelling, and choose to comply with it in these aircraft.

4) Do not go below MAP>(RPM/100) until you reach the runway threshold (the PMDG manual states 15" for the flare, and I think that works just fine).

4) Modern STARs are not relevant for propliner operations. While I have no experience flying large high performance piston airliners in the modern environment... it makes no sense to put the two together. As previously discussed, the 500FPM descent will not allow you to meet crossing restrictions oriented for turbine aircraft anyways. In the example of the MOTIF6 STAR to KMDW, notice that those charted altitudes are "Expect" only, meaning they must be assigned by ATC. Your response would very likely be "Unable" to such restrictions, and this descent angle is much too steep (and late) anyways. Also, consider that in the modern world a DC-6 is affectionately known as a "flying roadblock" to the turbojet/turboprop aircraft barreling down on it at 200KIAS+. You would either be rerouted off a STAR, or given vectors to get out of the way. Routing is likely to be very similar to the period correct procedures used at CalClassic.

5) I also disagree with Simon, in that MAP (considered with RPM) is a very good estimation of engine torque or power. Remember that while MAP only informs us of the amount of air delivered to engine, it is the carburetor's job to deliver an appropriately metered amount of fuel for combustion, based on the density of the air at the manifold. If I know MAP and CAT, then I know the density of the air charge, and thus can infer exactly the metered amount of chemical energy being delivered to the combustion chambers based on the setting of the automatic mixture controls.

There is yet MUCH MUCH more to these wonderful aircraft, and I would highly recommend dedicated users check out the resources available in the Propliner Tutorial and at CalClassic, and hope you guys can experience the satisfaction from mastering these demanding machines.

Robert Toten

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13 hours ago, randomTOTEN said:

4) Modern STARs are not relevant for propliner operations. While I have no experience flying large high performance piston airliners in the modern environment... it makes no sense to put the two together. As previously discussed, the 500FPM descent will not allow you to meet crossing restrictions oriented for turbine aircraft anyways. In the example of the MOTIF6 STAR to KMDW, notice that those charted altitudes are "Expect" only, meaning they must be assigned by ATC. Your response would very likely be "Unable" to such restrictions, and this descent angle is much too steep (and late) anyways. Also, consider that in the modern world a DC-6 is affectionately known as a "flying roadblock" to the turbojet/turboprop aircraft barreling down on it at 200KIAS+. You would either be rerouted off a STAR, or given vectors to get out of the way. Routing is likely to be very similar to the period correct procedures used at CalClassic.

 

I had no problems with sticking to the MOTIF6 STAR with the PMDG DC-6, I was able to comply with all the "expected" altitudes displayed on the charts, but I had to plan way ahead and make some calculations for it to work. Most of the time I use the "VCALC" function of the GTN650 installed on my DC-6, works quite well when you set your required altitude at the IAF as target altitude, then a descend rate of 500 FPM and lastly a 10NM offset before the planned waypoint, so that you are able to slow down below max. flap extension speed before passing the IAF. But you have to make sure that you won't descend below MSA in order to thet to the IAF (e.g. in a mountainous area). If I'm face with such a problem, I request a hold with descent clearance to the IAF's minimum required altitude before continuing the approach.

If you're searching for an interesting and challenging approach for the DC-6, try BGBW (Narsarsuaq, Greenland). I've landed there last week. Did the NDB/DME-1 approach for runway 07. Aircraft that are not able to fly the steep approach path (5.6°) have to overfly the threshold and then make a 360° turn to the left. That was fun in the DC-6, as you don't have much time to lign up to the runway on short-final after flying that 360° turn!

Edited by TheFinn88

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On 9/17/2018 at 3:04 AM, TheFinn88 said:

I had no problems with sticking to the MOTIF6 STAR with the PMDG DC-6,

That's great to hear. What was your IAS on the arrival?

On 9/17/2018 at 3:04 AM, TheFinn88 said:

Most of the time I use the "VCALC" function of the GTN650 installed on my DC-6... request a hold with descent clearance to the IAF's minimum required altitude before continuing the approach.

I do the same thing. I haven't brought myself to install a GPS unit in the aircraft yet, and got intimately familiar with the panel mounted clock on my most recent flight. 😎

On 9/17/2018 at 3:04 AM, TheFinn88 said:

try BGBW (Narsarsuaq, Greenland)... NDB/DME-1 approach for runway 07.

This looks like a wonderful little approach, and I can't say no to a scenic NDB approach such as this. Thank you for the suggestion. As you've mentioned, and others might not realize, despite the very close proximity of 5,500'+ mountains to the airport, this is not categorized as a "steep approach." At most, it is "optionally steep" and I would agree with your decisions regarding this approach. The DC-6B likely cannot comply with the 5.6 degree glide slope for a straight in from the 1,800' minimum descent altitude. It also likely cannot achieve the required 4% minimum climb gradient for a missed approach from 1,800'.

But even with such close terrain, it certainly can comply with standard descent gradients to the 3,500' MDA, and then descend via a normal 3.0 degree path in a casual circle under visual flight to the runway. Should a missed be executed from 3,500' the DC-6B will meet the required climb gradient for a safe return to 6,800'.

I noticed that the chart doesn't list visibility minimums for any category, so I found them in another document. Regardless of either a "steep" straight in or "normal" circling procedure, 6,000 meters of visibility (about 3.75 sm) is required to descend below the chosen MDA. If the approach is conducted at night, then only the straight in is authorized. This means that the the PMDG DC-6B is likely only authorized to arrive at BGBW during daylight hours.

Somebody would need to test to see if the steep approach is possible (Real operators would likely calculate the possibility), but I have full confidence that normal gradients can be met.

Are there any operators/routes which would have flown a DC-6B into this airport? I'd like to make this approach part of a complete flight if I can.

Robert Toten

Edited by randomTOTEN

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6 hours ago, randomTOTEN said:

That's great to hear. What was your IAS on the arrival?

I was cruising at 13'000ft, so I started my descend at the first waypoint with the first expected altitude at RENZO. But before I started my descend, I decreased my airpseed to 140 KIAS and dropped my flaps to 20° as soon as I was below 170 KIAS. With flaps set at 20° and an airspeed of 140 KIAS I had a descend rate of about 800 fpm, and I was able to cross MOTIF at 10'000ft and the Joliet VOR at 6000ft. I was also quite light with a LGW of about 72'000 lbs.

6 hours ago, randomTOTEN said:

I noticed that the chart doesn't list visibility minimums for any category, so I found them in another document. Regardless of either a "steep" straight in or "normal" circling procedure, 6,000 meters of visibility (about 3.75 sm) is required to descend below the chosen MDA. If the approach is conducted at night, then only the straight in is authorized. This means that the the PMDG DC-6B is likely only authorized to arrive at BGBW during daylight hours.

I use navigraph charts for my flights, and they state the minimum visibility (6000m) and minimum cloud base (1500ft) required for a approach into BGBW. And I actually didn't took into account the missed approach requirements, good that I didn't have to go around. :blush:  I landed there before the sun went down, and I wouldn't recommend to fly in there at night with the DC-6!

The departure out of BGBW is also very interesting. There are two options, one is to directly intercept the 277° bearing out of the NA NDB, and the other one is to fly a 360° to the right within the 3NM arc of the NQ DME. I flew the 360° departure, and after that you have to correctly lign up on that 277 bearing, as this will keep you over the water and between the mountains. So I had to fly about 7 minutes into the wrong direction and climb to 7100ft (MSA) before turning back to the NA NDB and continuing my flight to BIRK. Also don't take off below take-off minimums, as you desperatley need visuals for that 360° turn. I had few clouds at 900ft, where I punched through some of them while making that 360° turn. :rolleyes: But I always had visual to the airport and the surrounding terrain, still it was very marginal...

My next leg will be from BIRK to EGPK.:cool: And by the way, regarding the DC-6 at LSZH: I've found a video of the RB DC-6 landing in LSZH on runway 28 with live ATC. They called in "established ILS 28" on a nice sunny day, I think that answers my question of whether the RB DC-6 is flown VFR or IFR into LSZH. :rolleyes:

Edited by TheFinn88

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