This part of the Savoia Marchetti S.73 package explains how to navigate the S.73 realistically. It is extracted from a prospective addition to the Propliner Tutorial available from Calclassic.com. Many other parts of the original Propliner Tutorial also apply to the S.73.


THE FOUR PHASES OF AVIATION HISTORY

Aviation history is about much more than aeroplanes because the things achieved by aeroplanes and those who fly them depend on a complex external infrastructure that is often ignored. What each phase of aviation has in common in every country, whenever it arrives, is nearly identical public sector aviation infrastructure, (civilian or military), regardless of aircraft diversity or airline ownership and control. 

The pioneer phase of aviation in each nation, or sector of aviation, was characterised by irregularity of service and high death rates due to inadequate public sector infrastructure. Aircraft were operated by pilots who had no formal training or qualifications in wireless operation or aerial navigation. They compared a road map to the scenery as it went by and often became fatally lost. Being a qualified pilot is not the same thing as being a qualified navigator. 

The vintage phase of aviation that followed, (everywhere except the Continental United States = CONUS), was characterised by large flight deck crews including a qualified wireless telegrapher and a qualified navigator. They used global positioning systems (GPS) to navigate without reference to the scenery. Using GPS they flew direct from departure to destination. Those vintage era GPS techniques were never adopted over the CONUS which moved directly to the third and classic phase of aircraft navigation. On the other hand the European powers, and their associated world wide empires, progressed much sooner to the vintage phase of aircraft navigation.

How we should conduct a realistic propliner, maritime patrol, or bomber simulation within FS9 depends on;

1) crew complement

2) the avionics being simulated

3) location

4) date 


By the time that the Savoia Marchetti S.73 entered service with SABENA in February 1935, followed by Ala Littoria in November 1935, most European empires, including the Belgian and Italian empires, had already entered the vintage phase of aircraft navigation. Airlines no longer relied on seeing any scenery to maintain an airline schedule, and no longer relied on primitive post medieval navigation devices such as sextants. They used GPS.

GPS does not require orbiting satellites to generate the necessary electronic signals. That is just a characteristic of the latest system. Earlier systems were terrestrial.


THE VINTAGE PHASE - GLOBAL POSITIONING SYSTEMS

The vintage phase of aviation dawned with the arrival of highly trained and qualified wireless operators (wireless telegraphers), and highly trained and qualified navigators who joined the flight deck crew, and sometimes displaced pilots as captain of the aircraft.

When we use any flight simulator we must always act as both pilot flying and aircraft captain. Performing other crew roles is optional. This tutorial provides a framework for piloting and captaining aircraft in the vintage phase of aviation. If you wish to role play telegrapher or navigator you will need to obtain a different tutorial.

Both Wireless Telegraphy (W/T = Morse) and Radio Telephony (R/T = Voice) pre date the powered aeroplane. Aircraft use of electronic global positioning for navigation dates from the Zeppelins of the Imperial German Navy. A Wireless Telegrapher or Radio Operator asked an operator on the surface to manually direction find (D/F) the aircraft's transmissions in the High Frequency H/F waveband. The ground operator used a large rotating Adcock array. The bearings supplied back to the qualified WTO or RO were then plotted on a chart by a qualified navigator. Ideally three bearings from different D/F operators in sequence were used to triangulate present (actually recent) position. Just as in a surface ship the airship navigator then instructed the helmsman what heading to steer based on where the vessel was believed to have been a few minutes earlier.

By 1935 many airliners including the Savoia Marchetti S.73 had combined gyroscopic compasses and course deviation monitors. In some airliners including the S.73 these were already combined within a wing levelling autopilot which drove the rudder trim tab when activated. It is important to understand however that the assigned heading was always bugged whether or not the wing leveller was going to be used. The heading assigned by the navigator was dialled into the assigned heading monitor on the upper scale of the gyro compass. The actual heading revolved below. As pilot flying we must always keep them superimposed, but after dialling current and assigned heading into the comparison compass we actually do that using the heading deviation compass above.

Today in the 21st century pilot flying is assigned headings by qualified radar controllers looking at a radar plan position indicator (RPPI). In the vintage era he was instead assigned headings by a navigator looking at a GPS display which he was updating manually. It makes no difference at all to us as pilot flying in FS9, or to us as the aircraft captain in FS9, who mandates the assigned heading, or whether they are aboard the aircraft. Actually it makes no difference in real life either. 

Today a GPS can update the aircraft plot in less than a second. In 1915 or 1935 it took a few minutes to use GPS signals to update the GPS plot in an ocean liner, a battleship, or an aircraft with the relevant crew complement and H/F wireless transceiver.

Using GPS to simulate the pioneer phase of aviation symbolised by the single crew Ford 4-AT-E Trimotor is cheating and is pointless. Using GPS to simulate the vintage phase of aviation which followed is entirely realistic. Most FS9 users fail to differentiate between the two phases and therefore fail to deploy GPS correctly during propliner, (and military or naval), simulation of the vintage phase of aviation.

Remember the pioneer and vintage eras of aviation, overlapped in different places, and in military v naval v commercial aviation infrastructure at the same time.


THE NEED FOR Radio Direction Finding (RDF)

Nobody believed that aeroplanes could achieve scheduled operation using sextants for astronavigation. Attempts usually ended in death, but even when hampered by the critically low endurance of aeroplanes a qualified navigator could get lucky a few times with a sextant and live to tell the tale.

Think about how useful a sextant is when the entire flight has to be conducted in or below cloud, or in limited visibility. Sextants only work well enough to be useful in vessels that can afford to have little idea where they are for days on end. That sometimes included airships, but not aeroplanes. Of course sextants were installed in some aeroplanes. They were just useless weight much of the time in any aircraft that had to maintain a schedule. 

Sextants were much used by military and naval aviators, because their command structure could just postpone missions for days on end until the weather was good enough to navigate using post medieval means of navigation. Under combat conditions radio silence may be necessary. Post medieval means of navigation were sometimes all that were available during 20th Century combat missions, or during training for combat in radio silence, but airlines were not constrained to radio silence, except in a very few places during WW2.

Radio Direction Finding = RDF, (in the HF band = HFDF pronounced Huff Duff), began to replace sextants for oceanic navigation world wide from 1909. The RMS Titanic was being navigated by RDF when she struck an iceberg in 1912. Aircraft were simply no different. By 1912 few vessels in the developed world attempted scheduled ocean crossings without both a qualified wireless operator and a qualified navigator aboard. It soon occurred to the Imperial powers that the Sahara, the Arabian Deserts and the equatorial jungles of Africa were just another kind of ocean. Then the Imperial powers decided to treat the entire planet as an ocean whose mountains were just another kind of reef. The entire planet could be navigated using GPS, not just the oceans, and it was.

By 1929 RDF was possible using HF stations 1200 miles away, *in any direction*. HFDF provided wide source infrastructure to vessels in transit, whether on the sea or in the air. When using wide source infrastructure, however the GPS signal is delivered and decoded, the vessel does not navigate from GPS transmitter to GPS transmitter. It receives their signals anywhere and everywhere. They are wide source not point source. Consequently the vessel attempts to navigate directly from point of departure to its destination without zigzagging across the planet from one radio beacon to another.


AIRCREW COMPLEMENT CONSEQUENCE

Across the British Empire RDF was a viable global positioning system (GPS) before WW1 never mind WW2.

Aircraft with significant useful loads had large crews, whether military or commercial, precisely because they used the form of GPS known as RDF to navigate. That is why a Boeing Clipper, or a Savoia S.73 could not have a DC3 flight deck complement of just two pilots, who only knew how to find and follow a series of radio beams from one point source beacon to the next. 


FLIGHT BY U.S. AIRCRAFT OUTSIDE THE CONTINENTAL UNITED STATES

The USN deployed RDF from 1918 onwards, but they did not share it with anyone else, (unless for one off propaganda purposes). The early US airlines had neither point source navigation infrastructure, nor wide source navigation infrastructure. Their fatality rate was dreadful. Over the CONUS the federally imposed detailed procedures that gave rise to the third and classic phase of navigation were introduced from 1932. Outside the CONUS all US aviation slowly caught up with the USN, the European powers, and everybody else, by introducing RDF.

When using FS9 we must never forget that for aircraft with large useful loads, everywhere except over the CONUS, GPS in the form of Marconi + Adcock RDF was the primary commercial, military and naval navigation system in use from WW1 onwards. During and after WW2 it was gradually replaced by LORAN, GEE, Decca Navigator and OMEGA, but from our perspective of both pilot flying and the aircraft captain each is just a slightly longer ranged, or faster decoding, or slightly more accurate GPS. Somebody else in the aeroplane operated each of them to create the GPS plot.

How the GPS signals were decoded at a particular date is not the point. The point is that with a large enough crew of specialists the captain of a Savoia S.73, and pilot flying if a different individual, both had access to GPS in 1935 whilst the instrument rated crew of a DC-2 flying over the CONUS in 1935 navigating along the audio beams generated by point source radio ranges did not.

The Savoia S.73 did not use point source radio navigation in the en route phase. It used wide source radio navigation (GPS). Just because two aircraft existed at the same time on different continents does not mean that their operation and navigation was similar. They were not. The tiny crew complement of land based US airliners required very expensive point source public sector infrastructure. Each of the hundreds of Radio Ranges required a power supply from a nearby power plant. By the 1930s that was possible within the CONUS, but it was totally impossible in the middle of the Sahara desert, or the middle of the vast African rain forests. Everywhere outside the CONUS wide source infrastructure was already in use and vessels in transit, whether on the surface or in the air, had the necessary crew complement to use it to create their GPS plot.



REGULATORY CONSEQUENCES

RDF provided a wide source infrastructure. Unlike Radio Ranges and the hardly different VHF Omni Ranges (VORs) that replaced them it was not associated with federal regulations, airways, en route air traffic control, or mandated procedures.

Everywhere except over the CONUS Huff Duff was widely available allowing multi crew aircraft to navigate above cloud without visual reference to the surface, and just as easily within cloud, or below cloud, without visual reference to heavenly bodies for astro navigation, on a scheduled basis, even in really bad weather. 

Every government except that of the United States wanted wide source navigation systems (GPS) to be the basis of post WW2 international aerial navigation, despite their short comings, since they had to be maintained for use by all kinds of marine vessels anyway. The shortcomings of all the early GPS systems were complex radio encoding requiring a dedicated wireless operator whilst manual plotting of the position decoded also required a qualified navigator. Not much problem in a ship, but for the US domestic airlines, already accustomed to two crew IFR operation using point source radio beams over the CONUS, a huge commercial problem in an airliner. 

The US view prevailed and GPS is still fighting for acceptance as a primary aerial navigation system despite automatic real time decoding and plotting. Both real time decoding and plotting have been available in British GPS moving map systems such as Decca Navigator since the early 1950s. 



SIMULATION OF RDF GPS IN FS9

In theory the FS9 GPS code could be made to behave exactly like a human navigator waiting for decodes from a human WTO before plotting the symbol on the map with suitable inaccuracy and delay, but this is not really necessary. 

The rules for conducting a GPS navigated flight using Marconi + Adcock technology during the vintage phase of aviation history only requires self disciplined use of the default FS9 GPS.

1) The aircraft, (whether civil, military or naval), must have at least a qualified WTO and a qualified Navigator. 

2) The GPS window must be 'popped up' only at substantial intervals during cruise; perhaps every 10th minute for a short haul flight, or every 30th minute for a long haul flight. 

3) Once every such position update interval, a course correction not exceeding five degrees, and always rounded to five degrees, is made after using the GPS to establish whether the flight is currently left or right of flight plan track due to wind drift and any other cumulative navigation errors, (that we have perpetrated). 

What we will be simulating using intermittent course changes and headings, which will be wrong by up to four degrees 80% of the time, is the error that arose from the manual plotting delay and the bearing errors inherent in using HFDF as the contemporary GPS system at extended range. 


CREW RESOURCE IS THE KEY

Multi crew aircraft outside the CONUS knew roughly where they were all of the time, in any weather, using RDF as a slow to update and slightly inaccurate GPS. Aircraft like the Ford 4-AT-E Trimotor with inadequate crew resource could still only fly the pioneer way by visual reference to the scenery.

Classic era airliners like the Boeing 247, DC-2 or DC-3 had two pilots, neither of whom was a trained navigator, and neither of whom was a trained telegrapher. They used point source navigation and followed audio beams, zig-zagging from beacon to beacon. That classic phase method of navigation did not exist outside the CONUS.

So during the vintage phase of aviation, everywhere except over the CONUS, (which never had a vintage phase), a flight in an aircraft with adequate crew resource for GPS navigation begins with a visual departure flown by visual reference to the surface until clear of all potential obstructions. This is followed by a climb to design cruising level, whether or not design cruising level is in cloud, below cloud, or above cloud, directly on track to destination. Then every ten to thirty minutes, FS9 GPS is used to adjust heading left or right five degrees in units of five degrees until the flight reaches a position where it is deemed to be safe to descend again near to destination. 

Of course any aircraft may need to climb above design cruising level to clear a mountain range, or descend below design cruising level to clear ice, in the absence of de-icing equipment. In 1935 very few aircraft had any de-icing equipment beyond carb heat and pitot heat. Equally some stages may be so short that it is not possible to reach design cruising level.

Note especially that no RDF signal is needed from destination, or anywhere en route to destination. The GPS stations in the 1930s were up to 1200 miles away from both the aircraft and its destination. 


LIMITATION OF UTILITY OF RDF

The slowly updating and somewhat inaccurate GPS used by the navigator of the Titanic in 1912 was not adequate to enter a harbour blindly in fog without reference to the local scenery. Nor was it good enough to allow an aircraft navigator to find a particular runway without visual reference to the local scenery. However, the GPS of 1912 was good enough to navigate from somewhere close to Ireland to somewhere close to New York, whether by a ship, or by aircraft. With sufficient training and skill, both undersea motionless reefs, and continental mountains, marked on a (GPS) chart could be avoided. Moving icebergs could not.

Just because the GPS systems used from 1909 to the 1990s were too poor to be used as approach aids, or could not be used to avoid collision with other moving objects, does not mean that they could not be used, or were not used, for en route navigation. Of course they were. Unless radio silence was required fro combat operations GPS was the primary means of en route navigation in any vessel with a qualified crew complement and save for the CONUS continental land masses were just treated as another kind of ocean with bigger rocks and reefs projecting above their surface.

Most FS9 users never quite grasp this. Sextants are occasionally useful in aircraft with enough power to climb above all cloud, but vintage airliners needed to maintain a schedule. On many days, and on many legs, a sextant would have been as useful as a chocolate coffee pot.

Now notice that the Savoia S.73 does not have an astrodome. One or usually both of the pilots is also a qualified navigator. They are both qualified to use a sextant, but there is nowhere for either of them to stand and use a sextant. There was no sextant. The S.73 was navigated using GPS, not astro-navigation. Now think about all the other airliners and aircrew flying schedules, whatever the weather, who could not rely on post medieval navigation techniques and who had no reason at all to maintain radio silence. Most of the airliners they were flying also had no astrodome and no sextant. When flying boats were used as airliners they often did, but they also tended to lack the power required to climb above cloud to take astro shots, so they too were heavily reliant on GPS.

In the real Savoia Marchetti S.73 pilot not flying (PNF) was the navigator. He maintained the GPS plot on his lap. Every ten minutes he worked out whether the airliner was left or right of flight plan track and if necessary assigned a different heading to pilot flying (PF). In many vintage airliners the comparison gyro compass was placed where PNF could update the assigned heading for PF. 

FS9 users may have come to think of the comparison gyro compass as part of a vintage era autopilot, and it may be, but that is not its primary use. The assigned heading is always bugged, (usually by PNF), and equality maintained by PF. In FS9 we must play both roles. Only every ten or thirty minutes we must pop up the GPS window and determine whether we are converging with flight plan track. If not we bug a heading five degrees more convergent with flight plan track and then we fly it. Whether or not we intend to use an autopilot to maintain the assigned heading. An AP is a luxury in any vintage airliner. A gyro comparison compass is not.

We never bug a heading that is not divisible by five and we never attempt to navigate direct to anywhere many miles ahead. We always bug and then fly a heading that converges with our flight plan track. Unless of course our current bugged heading is holding flight plan track exactly in the current crosswind. If we are using real weather, that happy co-incidence will never last for long.


LOCAL INFRASTRUCTURE CONSTRAINT

O.K. let's consider the rules of conduct for flight simulation of a SABENA Savoia Marchetti S.73 flying the London to Oostende schedule in the winter of 1939. On this flight we can use Belgian and British commercial aviation infrastructure which includes GPS widesource signals, but not point source Radio Range signals of the kind that were in use in the United States. It will be cloudy and raining a lot of the time. We do not wait for clear blue sky because we do not need to climb above cloud to take sun shots. We have nowhere to stand to take sun shots with a sextant anyway. We do not wait for high visibility at low level because we do not intend to navigate en route by reference to the scenery. 

We could use ancient pioneer era, flight by visual reference to the scenery, navigation techniques to locate Oostende, but our track mileage will be less if we use GPS to proceed in a straight line, and SABENA are not paying the other three aircrew in our virtual cockpit for nothing. We will also enjoy a much faster cruising velocity up at 4000 metres in nice thin, low drag, air.

If we have not installed a third party scenery of Croydon we will use nearby Redhill (EGKR) in FS9 instead.  We must climb out over the local terrain to somewhere safe, by reference to the scenery, potentially using a map, before climbing into or above cloud. Climbing out of Croydon or nearby Redhill that will be no problem, but in Africa which was the natural home of the Savoia S.73 it may be a significant problem due to high mountain ranges. 

Once in the cruise at an altitude of four thousand metres, potentially above, or quite often within cloud, cruising fast at high TAS in nice thin air, the goal is to transition from the en route phase to the arrival phase using GPS to decide when it is safe and appropriate to descend.  This is a short haul schedule, so we pop up the FS9 GPS window only once every ten minutes and make course changes of no more than five degrees in units of rounded five degrees until on one of those updates we decide it is time to descend. This is the key captaincy decision when navigating using GPS in the vintage phase of aviation. It is the descent through cloud that may kill us all. 

At this point the Classic phase techniques already in use in the United States and the Vintage phase techniques in use everywhere else merge and become identical. The means of terminal guidance was becoming universal. Non Directional Beacons, (transmitting in the Medium Frequency band), were becoming common. However Automatic Direction Finding (ADF) was still a rarity.

Sometimes only the middle third of a short haul flight undertaken in the vintage phase of aviation outside the CONUS will be conducted using GPS, but San Francisco to Honolulu would be RDF = GPS more than 95% of the way. In real life the way an aircraft is operated has nothing to do with the aircraft type or its date of manufacture. It depends on the current technology phase of the local aviation infrastructure. That is what we must seek to replicate and simulate within FS9.

By 1939 the R.A.F. had already had fourth generation modern phase infrastructure within Britain, but British commercial aviation which spanned an empire was stranded in the vintage phase. This constrained the operation of commercial aviation over and near Britain whether the airline was British, Belgian, Dutch, Danish or German.


PLANNING TOP OF DESCENT (TOD)

In the vintage era of aviation there were no mandatory arrival and approach procedures published by a federal agency via an arrival and approach plate. The key flight planning decision was always voluntary placement of top of descent (TOD) to terminate the limit of the GPS component of the vintage phase flight outside the CONUS. We must descend through cloud somewhere that does not risk collision with terrain in the descent. We must plan and then vertically limit the descent accordingly. 

There were no federally mandated procedures outside the CONUS, so they were employer mandated instead. In general the present day federally mandated procedure is just an amalgam of the prior employer mandated procedures many of which date back to the thirties. They are the same thing really, so if a current NDB arrival and approach procedure is available for download, it should be downloaded and followed. Even if it appears that a modern STAR has no relevance to vintage airliner operation in the 1930s it probably does. The current approach plate is always relevant. It tells us what our minimum descent altitude must be in FS9 since we must avoid masts present in FS9 whether or not they were present in the thirties, forties or fifties.

The rules for planning top of descent are therefore those explained in the original Propliner Tutorial available from Calclassic.com even though it addressed only flight in the Classic phase of aviation history.

In FS9 we will use GPS to navigate the Savoia S.73 as explained above until it is time to descend. Then we will switch to terminal guidance which is identical to terminal guidance in the classic phase already in use over the CONUS.


THE ARRIVAL PHASE

Part 3 of the Propliner Tutorial explains in detail how to fly arrivals and non precision approaches in propliners, whether they are vintage or classic era propliners. Whether over the CONUS or anywhere else that vintage/classic phase arrival and approach guidance infrastructure was, and still is, in place today.

Oostende (EBOS) still has all of its vintage and classic era terminal guidance navigation infrastructure present within FS9. Three NDBs, and two Lorenz Beams. All the vintage era infrastructure we could possibly need in a Savoia S.73 or any other vintage/classic propliner. 


GONIOMETERS

However what vintage airliners lacked was ADF to home those NDBs. Vintage era propliners had Goniometers instead. 

The standard American Goniometer is called a U.S. Army Aviation Section Signal Corps Receiver (USAASSCR), or just Signal Corps Receiver (SCR) for short. It is of course a default gauge in both of the default FS9 Lockheed Vegas. It is mounted to the left of the Altimeter in their VCs, immediately above their all important gyro comparison compass. In the Savoia S.73 the European pattern goniometer is underneath the Air Speed Indicator. It works just like the FS9 default goniometer, but I have a nasty suspicion that most FS9 users have never bothered to learn how to use a goniometer. Shame on you! Now you have another chance, and the tutorial that Microsoft could not be bothered to supply.

An ADF is also called a radio compass. It has a 360 degree compass within a circular gauge. An automated system points the ADF needle at the NDB which we tuned using the avionics panel. The Goniometer is not automatic. It uses the circular MFDF loop on top of the aeroplane, in this case on top of the Savoia S.73. We tune it the same way as an ADF though, and to the same frequency.

The MFDF loop is there mostly for use by our virtual telegrapher during the en route phase. It is mounted on a periscope stand and operated just like a periscope. The telegrapher turns the periscope until the signal minimises. Then he notes the bearing from the base of the periscope stand just like a submarine captain taking a bearing on a ship to the beam. Over the second and third world where NDBs are very few and far between our virtual telegrapher must employ the Huff Duff techniques described earlier instead. 

The telegrapher may swing the loop aerial manually during the en route phase. However just before top of descent he locks the MF loop facing forward and the telegrapher tunes the NDB that is the initial approach fix (IAF) for destination. Then he informs pilot flying that the blind flying panel goniometer is tuned. We must tune the goniometer to the NDB, by popping up the avionics window in FS9.


BEACON (NDB) APPROACH

The goniometer has no automation. The MF loop has no automation. Pilot flying (we) now turn the whole aeroplane manually until the NDB which is the IAF for our approach is on the nose, using the obscured arc goniometer (SCR) to determine when it is dead ahead. Now we home to the IAF, keeping the needle pointing ‘straight up’ just as though we had a radio compass (ADF) even though we only have a goniometer and a locked MF loop.

We can fly any vintage era, classic era, or current era NDB arrival, holding, or approach procedure using a goniometer. ADF is a ‘modern’ luxury that is not required to fly modern era approaches.

Why not repeat the exercises in Part 3 of the Propliner Tutorial using the Savoia S.73 and its goniometer. Don’t try the goniometer approach to Moosehead Lake aquadrome though. That one is strictly for the Calclassic updated Grumman Goose!

I am not going to repeat everything in Part 3 of the Propliner Tutorial here. You can download it from the Tutorials section at Calclassic.com. The only difference when flying a Savoia S.73 instead of a Goose or a Convair 440 is that we use a goniometer instead of an ADF to fly the holding pattern, the arrival, and the approach.


LORENZ BEAM APPROACH

These days everybody calls Lorenz Beams, Localizers. Around 1939 the British used to call them Standard Beams, because they wanted to pretend they were not reliant upon a German technology. However a Lorenz Beam Approach (LBA), A Standard Beam Approach (SBA), and a Localizer (LOC) approach are all the same thing. LBA gauges use a vertical LOC needle to find and then follow a Lorenz Beam (Approach) to a runway threshold.

Others like the Standard Beam Approach (SBA) gauge in the DZN L-049A Constellation for FS9 use a pair of lights to indicate left right guidance to find and then follow the Lorenz Beam (LOC). The use of a needle makes the gauge an LBA gauge following the German pattern and the use of lights makes the gauge an SBA gauge following the American and British pattern. The Savoia S.73 has a German pattern LBA gauge to the right of the Goniometer.

Unlike an NDB, Lorenz Beams promote straight in approaches to specific runways and allow much lower minima because they are precision approaches providing terminal track guidance inside the Final Approach Fix (FAF).

A Lorenz Beam Approach can be attempted without flying a holding pattern for inbound track guidance first.

Berlin and New York had Lorenz Beam Approaches in 1936. The rest of the commercial and military world soon followed. Today Oostende has a Lorenz Beam at each end of its instrument runway.


STANDARD BEACON APPROACH

The Standard Beacon Approach must not be confused with the Standard Beam Approach even though they have the same abbreviation!

The Standard Beacon Approach combines one or more NDBs with a Lorenz Beam to provide easier interception of the Lorenz Beam (LOC) via one NDB and potentially distance to go data from a second NDB closer to the runway threshold.

All three Oostende NDBs (on different frequencies!) are conveniently located under the two Oostende Lorenz Beams.

Oostende (EBOS) offers Standard Beacon Approaches to both ends of its instrument runway and because it is adjacent to the coast Oostende is a great place to practice NDB approaches with a goniometer, and Standard Beacon approaches with the Goniometer and the Lorenz Beam Receiver together in the SABENA Savoia S.73 OO-AGL.

We should practice with good visibility and only moderate cloud cover at first, but eventually with two miles visibility, and 8/8 cloud at 700 feet, until we can maintain the London - Oostende SABENA S.73 schedule whatever the weather. 


NO APPROACH PLATE AVAILABLE FOR DOWNLOAD

I have provided copies of relevant, but out of date, EBOS plates originally uploaded by IVAO, so that everyone who downloads OO-AGL can fly the real procedures for EBOS. Don’t use them in real life. IVAO are a good source of other plates. As it happens the current EBOS plates are also a free download from Eurocontrol, but some aviation regulators do not provide free downloads of their current flight safety procedures. Then we must deduce the arrival and approach procedure for our destination using an FS9 flight planner.

Study the supplied EBOS plates. They relate to an airfield whose elevation is to all intents and purposes sea level. At another airfield the procedures will usually be the same. However the courses will be the runway courses of that other airfield’s runways and the altitudes to be flown will be displaced upwards by the elevation of the other airfield.

What we are required to do at a different airfield is the same thing at different altitudes and on different headings. The concept should be easy enough to transfer to Addis Ababa when fling I-ASTI, but the inbound course will be 253 and 2000 feet QNH must become 2000 plus 7624 feet = 9624 feet = 2934 metres and so on, because the elevation of HAAL is 7624 feet, not a few feet above sea level.

Before flying any approach in FS9 it is anyway a good idea to write it out in text form so that it is the ATC clearance for the approach. It makes the approach easier to understand.



ATC APPROACH CLEARANCE TO RWY 08 at Oostende:


After studying the plate supplied we would write;

Tune ONO. Descend to cross the RWY 08 Initial Approach Fix ONO at 3000 QNH = 920 metres.

After ONO fly course 103 and descend 2000 (QNH) = 650 metres

When level 650M QNH turn left to cross ONO on course 258

Tune DD. Track to DD.

After DD fly course 283 and descend 1400 QNH = 430 metres

When level 430M QNH turn left to cross DD on course 079

Descend 500 QNH = 170 metres before DD

If runway (lights) not seen over DD at 170M QNH go missed

Missed = climb track 079 to 2000 QNH = 650 metres

Tune ONO. Track to ONO. Enter ONO holding pattern 650M QNH

Repeat procedure or divert.


This will be flown using the Goniometer tuned first to the ONO on 399.5 Kcs and then to the DD on 352.5 Kcs.

No DME is involved in this vintage phase Beacon Approach procedure. By the 21st century, in the modern phase of aviation, a VOR+DME has been established at KOK to deliver a DME cross check. We simply ignore that modern development when flying the vintage phase approach.

I hear people saying they wish more vintage and classic era approaches were available for download. Many hundreds of vintage and classic era approaches are still in use around the world and available for free download.

This particular plate was uploaded to an FS site by IVAO, but it is copyright AIS Belgium and was made available by them as a public safety and training resource. Many such plates are available as free downloads direct from the relevant federal authority. Why not use FS9 to learn to fly real propliner procedures instead of just making them up? The nice thing about the real ones is that they actually work and are compatible with real(istic) flight dynamics.

Why not fly the procedure above in FS9 in steadily worsening weather which you control with the user menu until you can land the SABENA S.73 OO-AGL at EBOS in a fully realistic way with the visibility down to only 2 miles and 8/8 cloud at 700 feet.

Save a flight as start position to the west of Oostende descending through 1000 metres QNH and then practice, practice, practice in ever worsening weather. When the visibility is poor we may be too high to execute a straight in approach to RWY 08. No problem. We are then required to fly a tight left hand visual circuit at 500 QNH = 170 metres and then land on 08 from that visual circuit.

Now notice that if the wind requires the landing runway to be some runway other than 08 we can still fly this approach to 08 and then join the visual circuit for the landing runway. In a propliner the runway we make an approach to is often not the one we are cleared to land on. We must often ‘circle to land’.

Look carefully at the bottom of the real plate and you will see that propliners intending to circle to land must arrest their descent at higher altitudes according to their size. Vintage propliners with multiple engines can all be treated as class B, or single engine as Class A. In the Savoia S.73 (Class B) if the landing runway is not 08 we will arrest our descent at 660 feet QNH = 200M, cross DD maintaining 200M QNH and then circle to land at 200 metres. Whether the landing runway is 26 or 32 or 14. 

Circling to land on 32 or 14 after approaching 08 presents a nice skill challenge in OO-AGL. In 1939 many runways at international airports on major routes were only that size. We should also practice nil wind (worst case) departures from RWY 14 at EBOS. If we never attempt to use runways of that size in vintage propliners we will never understand what vintage propliners are all about. The Savoia S.73 is a huge bushplane whose airfield performance is as good a Beaver. It is a giant bushplane. It was optimised for use from African bush strips, not modern international airports.

Note that EBOS still has no co-located DME associated with its Lorenz beams even today. The DME needle on the LBA receiver will indicate zero whilst we fly the Goniometer approach and if we do not tune the Lorenz Beam, whilst we conduct Goniometer approach training, the LOC needle will give no guidance either. We don’t really need it. The Beacon Approach to EBOS QFU 08 explained fully above will always get us down, if we have acquired the necessary skill.


LBA + DME TRAINING

To conduct LOC+DME training we must continue down the SABENA route to Lille (LFQQ) south of Oostende where the Lorenz Beam has a co-located DME that will deliver height required data if we tune QFE by subtracting 157 feet = 48 metres from QNH. 


HEIGHT not ALTITUDE (QFE not QNH)

In both the vintage and classic eras of aviation approaches were flown with the Altimeter set to QFE so that they displayed height above destination runway, and not set to QNH to display altitude above sea level.

The use of QNH to fly approaches, with an altimeter displaying altitude, is a concept from the modern phase of aviation history. Consequently it is the default within FS9, but when flying either a an Lorenz Beam Approach (LBA with no NDB under the beam) or a Standard Beacon Approach (SBA with an NDB under the beam) we must always reset the altimeter from QNH to QFE.



SETTING QFE in FS9

To set QFE we need to know the altitude of the destination runway. We should always know that anyway during flight simulation, but it was even more important before the modern era. It can be discovered using a flight planning tool. Super Flight Planner is about the best freeware tool, but FS9 has a default flight planner that will allow us to discover the altitude of our destination runway. To set QFE we simply mouse the Kollsman knob on the Altimeter to subtract runway elevation from current altitude. We should work it out on the back of an envelope or if necessary with the Windows calculator first.

Ideally we will always download the real and current approach plate for our FS9 destination. That will tell us the real elevation to use of course, but not all AF2 authors use the data they should use when creating an AF2.bgl. That includes Microsoft.

Oostende is at an elevation of only 15 feet above sea level. We wind the altimeter down by 15 feet or 5 metres to set QFE instead of QNH. Our altimeter now displays height not altitude.

We do this just before we cross the Final Approach Fix of the approach, or just before intercepting the Lorenz Beam, whichever is the sooner. That is the moment when we lose interest in our vertical displacement from the sea (our altitude) and gain interest in our vertical displacement from the instrument runway (our height).

When flying I-ASTI into Addis Ababa in the winter of 1939 we must instead subtract 7624 feet (2324 metres) from the current reading on our altimeter to obtain a QFE height reference since that is the elevation of the instrument runway at HAAL within FS9.



REAL PROCEDURES

The reason that QNH is the international default today is mostly the invention of the Radar Altimeter. In the modern commercial and military cockpit the RADALT can display current height whilst the Altimeter continues to display current altitude.

When a cockpit has no RADALT, but has two altimeters, only pilot flying (PF) sets his altimeter to QFE to display height. Pilot not flying (PNF) retains QNH. That is the procedure in the Savoia S.73 cockpit.

Remember on the approach plate the elevations of mountains and masts are all altitudes (QNH). During final approach from the FAF or along the LOC PF loses his altitude frame of reference to concentrate on height. PNF continues to monitor altitude.


USING an LBA gauge

Take a hard look at the Lorenz Beam Receiver to the right of the Goniometer in the S.73 panel. It looks like an ILS receiver, but if you try to use it as one it will kill you.

The vertical needle is a LOC needle and it is used just like a LOC needle, but the horizontal needle is NOT a glideslope needle. It is a DME needle. It shows distance from the threshold of the instrument runway PROVIDED of course that the Lorenz Beam (LOC) in question has co-located DME in real life and therefore in FS9.

It is used as a DME needle in any approach that requires LOC co-located DME. However it has a second and primary usage which is why we always fly an LBA or SBA approach using QFE.

The horizontal needle of an LBA gauge is the HEIGHT REQUIRED needle. 

There are five check marks. These are at 8, 6, 4, 2 and 0 nautical miles DME.

However the Lorenz Instrument Landing System is European and metric. When a LOC/DME approach is flown using a metric altimeter set to QFE these LBA check marks must be crossed at 800, 600, 400 and 200 metres QFE.

The whole point of using QFE to fly the Beam approach is that these required height values never change for any runway, anywhere. They are identical at Oostende and at Addis Ababa, because by setting QFE we see displacement from the runway (our height).

As we descend along and track the Lorenz Beam (LOC) using the vertical needle for guidance we as Pilot Flying make sure our altimeter set to QFE never reads less than 800, 600, 400, 200 at each check mark as we descend along the Beam. Anywhere and to every runway. *But we must set QFE on the PF altimeter first.*

In the days before radar altimeters this was how height had to be monitored and how descent on the beam was monitored.

When we reach the penultimate check mark at 2 DME we should be at a height of 200 metres, anywhere and everywhere, and in accordance with (most) vintage era beam approach minima we must start a missed approach if we cannot see the instrument runway (lights) at that moment. The missed approach procedure is on every approach plate.

In 1939 we would not set off from London to Oostende, or from Oostende to Lille if the cloud base was below 200 metres or the visibility was less than 2 miles at destination. In FS9 we always check this before take off using freeware FSMETAR to obtain the destination actual (weather) that FS9 is using to generate cloud and visibility at EBOS or LFQQ. If we allow real weather to update during the flight, or allow user defined weather a non zero rate of change, it may deteriorate of course.

These procedures are specific to the LBA receiver in the Savoia S.73 package of which this file is a part. These procedures do not apply to all gauges with the same bitmap. They may have different code content. They may not be metric either.

Users of FS9 must be realistic concerning their own ability. Every FS9 user should teach themselves to fly NDB approaches (Beacon Approaches) using the Propliner Tutorial from calclassic.com. Every FS9 user should teach themselves to fly Lorenz Beam Approaches, Lorenz Beam + DME approaches and Standard Beacon Approaches using this tutorial in conjunction with the original Propliner Tutorial Part 3, BUT each user of FS will at any stage of their self training have a skill level less than a real 1939 airline pilot, (unless they are a real instrument rated pilot of course), and every user should use these tutorials to determine what their own level of skill and training currently is.

We must all determine what *our* cloud base and visibility minima are and observe them until more and more self training allows us to reach higher standards of skill, until we too can hand fly an approach in 2 miles visibility and with a 700 foot cloud base at EBOS, or LFQQ or anywhere else in FS9.

Happily the lumbering Savoia S.73, with realistic flight dynamics, carefully encoded gauges, and correctly encoded FS9 scenery projection, makes an ideal instrument rating trainer. Unlikely as it may seem the huge lumbering bomber equivalent (S.M.81) of the S.73 airliner was the real instrument rating trainer of the Regia Aeronautica. 

There is so much more to do with well designed FS9 freeware releases than use them as radio control models for thirty minutes before losing interest and demanding another passing visual novelty. Used wisely and well the Savoia S.73 can deliver hundreds of hours of self training and skill enhancement within FS9.

This tutorial is an addition to Part 3 of the Propliner Tutorial, not a replacement. Much that is relevant to flying the Savoia S.73 realistically is not repeated here.



AFTER WW2. 

En route to EBOS we use GPS to ensure that we descend through cloud early and over the sea. On the other hand if simulating a British South American Airways (BSAA) Avro Lancastrian schedule from Buenos Aires to Santiago in 1947 aboard the ‘Star Dust’, unlike the real captain, we must ensure that the navigator and telegrapher use GPS to instead ensure that we descend plenty late enough to have crossed the Andes before initiating descent. 

What most commentators on these issues fail to comprehend is that the headwind encountered is irrelevant and the cloud base is equally irrelevant. Flight by visual reference to the surface scenery is irrelevant. The flight must be conducted using RDF based GPS else we are all doomed to die on a glacier on the wrong side of the Andes. The telegrapher in Santiago can D/F our normal H/F wireless traffic (COM not NAV) signal and tell us when we are due north of Santiago, and until then we must not descend. Above all we must never pretend that sextants and 'dead reckoning' can be used to navigate aeroplanes safely during scheduled operations. By 1947 thousands of aircrew had already died trying, and even in the U.K. it was almost time to end the pretence. The 'Star Dust' disaster would just hasten the end of that long standing pretence.

However in 1947 there existed many (British) aircrew who had been so extensively indoctrinated in maintaining radio silence during combat missions that they neglected to obtain the necessary RDF bearings to create the GPS plot when they became airline aircrew after WW2. BSAA propliner, after BSAA propliner, manned almost entirely by ex RAF Bomber Command aircrew, became lost with fatal consequences. None of these losses was mysterious. The aircrew did not obtain the necessary RDF bearings to create the necessary, but not always mandatory, GPS plot.

This was the era of make it up as you go along aerial navigation. No mandatory flight planning procedures, often no worthwhile flight plan at all. The crew just glanced at the GPS plot and decided what to do next. The flight meandered backwards and forwards across the flight plan track turning five degrees right and five degrees left depending on which way the mid course line was. Only TOD was ever really planned and checked at all, and some captains and some navigators just guessed, (dead reckoned), that too. They soon reckoned wrongly and were soon dead. 

We should always plan TOD carefully. During vintage phase navigation TOD has nothing to do with the runway location. It has everything to do with where the initial approach fix (IAF) is and the bearing from which we must approach the IAF to remain clear of mountains.

If when simulating operation of a BSAA Lancastrian setting off from the Azores to Bermuda in the late 1940s, we use dead reckoning, or better still a sextant, then we can personally simulate starting the Bermuda Triangle myth because we have no chance of finding Bermuda in bad visibility. It could not be located without RDF in the late 1940s any more than Howlett Island could be found by a Lockheed Electra with no trained or qualified telegrapher aboard a decade earlier. A highly qualified navigator had never been enough to keep anyone aboard alive. In the vintage phase of aircraft navigation GPS required a qualified telegrapher too. The Savoia S.73 always had one. He was there for a reason.

There has never been the slightest mystery why BSAA Star Dust or Earhart and Noonan disappeared 'without a trace'.

The 'trace' in question is the line on the ground or ship based D/F operator’s oscilloscope that shows the bearing of the transmitting vessel. He tells the on board telegrapher what that bearing is using Morse code. The WTO decodes it and tells the navigator. The navigator updates the GPS plot and nobody dies. If the vessel had no trained WTO everybody died sooner or later. If the qualified WTO, (who was rarely the captain of the vessel), was never ordered by the navigator or the captain to obtain a radio bearing everybody died sooner or later.

In the vintage phase of aviation history the key to survival was a large crew complement, professionally trained and qualified in diverse but essential skills, and above all who were sufficiently well trained and indoctrinated in the use of RDF based GPS. Those with the wrong training and the wrong indoctrination had ‘the right stuff’ for combat flying in radio silence, but ‘the wrong stuff’ for airline flying in safety. 

British airlines like BSAA were still stranded in the pre Zeppelin era of aviation history, even in the late 1940s. BOAC were reliant on wide source infrastructure and still not subject to adequate safety regulation of the type that had been introduced over the CONUS from 1932. Both British airlines still had the fatal accident record to match. Aircraft have such short endurance that they are much more vulnerable to navigation error than ships.


TIME TO RECAP.

The S.73 was carefully designed to utilise vintage phase en route navigation techniques and, as soon as they were available, location by location, also classic phase terminal guidance techniques such as Beacon approaches and Beam Approaches. The departure was always flown visually, just as it had been in the pioneer era. On some flights, if the weather permitted, the crew could just follow a coastline in the en route phase, but there was no coastline, river, or railway for SABENA aircrew to follow crossing the Sahara or the vast equatorial rain forests of the Belgian Empire where SABENA Savoia S.73s did most of their flying.

Do not confuse the wide source GPS signals used by the WTO and navigator in the S.73 with the point source radio beams used by the two pilots of a DC-2 to navigate over the Continental United States (CONUS) in the same timeframe. 

The S.73 did not zig zag from one beacon to another beacon. It used radio signals from a Global Positioning System whose radio source was up to 1200 miles away in any direction. The navigator who was Pilot Not Flying, used that GPS plot to give vectors to Pilot flying, often reaching across to set the revised assigned heading on the gyroscopic comparison compass. He vectored pilot flying just like a radar controller who looks at where a blip is on a radar screen and roughly estimates the heading required to get to somewhere else on the same radar map. There is no beacon and no beam pointing to that waypoint.

In the 1930s point source navigation (Radio Ranges) existed only over the CONUS and along some parts of the Lufthansa network. Because low frequency (L/F) band radio ranges were also blind bombing beams, and were much used for blind bombing by the Luftwaffe 1939-45 there was a great deal of reluctance to install them after WW2. Nevertheless under pressure from the United States, most of Europe nevertheless adopted point source Radio Ranges in the late forties, only to replace them as quickly as possible with VHF Omni Ranges (VORs) from the mid fifties. In the second and third world the vintage phase navigation techniques lasted much longer.

With only two crew the DC-2 and DC-3 were poorly suited to European aviation infrastructure in the vintage phase of aviation history, but ideally suited to the classic phase that arrived in the late forties. They needed long range point source beacons creating beams for pilots, who were not navigators, to follow. They only existed within the CONUS and certain parts of the Lufthansa route structure prior to the late forties. Airlines like KLM and Aeroflot purchased DC-3s before WW2. They were fast, but they were a poor choice. Aeroflot and the Soviet Air Force soon redesigned the DC-3 to have a dedicated telegrapher so that Soviet GPS could be employed, thus creating the Lisunov Li-2.

When the Li-2s and later multi crew Soviet propliners were pensioned off by the Soviet Union in the sixties and seventies they were still optimal for use in many third world nations which still relied on vintage phase wide source navigation. In some parts of the third world the vintage phase lasted into the nineties. Vintage phase navigation is not about dates. It is about infrastructure and development in different nations at different times.

No precision is required or involved when navigating the Savoia S.73 and analogous aircraft, during the en route phase within FS9 during vintage phase en route navigation. Once every ten minutes we pop up the GPS window and turn five degrees right, or five degrees left, depending on which side of the desired track we seem to be. That is all. Nothing more. Nothing less.

The key captaincy decision is Top of Descent. We must descend through cloud somewhere safe. This may be well before the coast, or well after the mountain range. It just depends on the current leg and the nature of the obstacles that may kill us on that leg.  

Of course GPS is still available in a Savoia S.73 below cloud and at low level because it has the huge crew complement of specialised air crew needed to make use of vintage phase GPS. HF signals can be received at low level. MF signals used to drive the needle of a Goniometer or an ADF may suddenly disappear of we descend below the curvature of the earth or pass behind the shadow of a mountain. They bend. They wander. They are inaccurate. It is only safe to use Goniometers or ADF at short range.

The thing to remember is that vintage era HF band GPS was very long range, but slow to update. We should look at the GPS picture only once every ten minutes, then roughly adjust our heading based on what we see, then close the GPS until we are due another update in tem minutes time. After using GPS to descend safely through cloud, on a safe bearing, towards the IAF, we transition to using classic era terminal guidance with the Goniometer and at major airports the LBA receiver, which may or may not be able to provide DME as well as LOC data. Like everything else in aviation that depends on the local infrastructure outside the aeroplane.

We use the panel clock to time our GPS updates. Updating late is OK, but allowing ourselves to update at intervals of less than 10 minutes, or allowing continuous display of the GPS is cheating. Vintage phase GPS did not have that continuous and instant update capability.

FSAviator 12/07