Post by volkerboehme on Jan 30, 2009 14:17:23 GMT -5
This post is intended only for those who are attempting 'realistic' vintage era 4D navigation within MSFS. It extrapolates from the worked example (Venice) which still uses NDBs as arrival fixes in the modern era to an examination of the situation around Paris which does not. Classic era navigation differs anyway.
Within navigating the Fiat G.18V it explains that the en route phase should proceed to the initial arrival fix, not the initial approach fix (IAF). Le Bourget no longer uses an NDB as its initial arrival fix, but a couple of minutes with an FS9 flight planner makes it obvious which NDB may have been used as the initial arrival fix for Paris arrivals from the south east in days gone by. The Paris area has approach aids whose range is 22 miles and arrival aids whose range is <> 70 miles. We look for the NDB to the south east whose range is <> 70 miles. That is Bray (BRY = 277 Kcs). Since the IAF is Le Bourget (BGW = 334 Kcs) (even in 2009) the arrival route is BRY - BGW. Time of descent is about 36 minutes before landing if cruising at FL180. Bray is fifty miles before Le Bourget. We receive BRY and navigate to BRY before Time of Descent. The GPS flight plan track ex Turin is to BRY, not BGW, not LFPB.
We plan roughly what level to cross BRY based on the level we must cross the IAF at BGW fifty miles further on where the arrival phase ends and the approach phase begins. For simplicity let's assume the minimum level at which we are allowed to cross BGW in 1937 - 1943 is 1000 metres QNH, (it may well have been).
Our speed (KTS) in descent will be somewhere around 2.5 miles per minute in a G.18V. On average those fifty miles will take 20 minutes. No precision is required. We always plan -500 VSI descents. 500 ft/min is 150 metres/min. So we plan to cross BRY at roughly 1000 + 20 * 150 = 4000M having cruised at 5500M. In practice we descend a little faster than 500 ft/min = 2.5 m/s but at not more than 3.5 m/s and we will be level at 1000M QNH some miles before BGW whatever the wind vector on that track actually turns out to be today.
Since BGW is only an approach aid its range is only 22 miles. We locate BGW by leaving BRY QDM 312M roughly on track to BGW. We will only start to receive BGW around ten minutes later and ten minutes before we reach BGW. During the last ten minutes of the arrival whilst we have BGW driving our goniometer we improve our tracking to BGW so that we arrive over the Initial Approach Fix (BGW) tracking 312 at 1000M QNH. At 1000M we have zero possibility of colliding with big masts. Paris had a rather well known big mast even in 1937. We won't collide with LFPB outbounds going south maintaining 700M QNH until well south of the BRY - BGW track either.
After we cross the IAF (BGW) we go beacon outbound. For the sake of simplicity we maintain our track of 312 for 30 seconds. We might 'realistically' clear ourselves to cross the FAF (also BGW) inbound at or above 500M. We descend immediately to 500M at between -2.5 and -3.5 m/s. It will take less than 500/150 minutes < 3.33 minutes to lose 500M. The instrument runway track is 071. After 30 seconds we turn left rate 1 to track 071 + 180 = 251. After we are established QDM 251 we go outbound for one minute. Then we reverse course to track inbound QDM 071. We do so at rate 1 which takes exactly one minute which is why it is called rate 1 (180 deg at 3deg/sec). Then it takes about another minute to arrive back at the BGW which has become the FAF. We concentrate on achieving a track of 071 to the BGW so that our track will be 071 after the BGW with no course guidance. QDM 071 will not take us to the threshold of RWY 07. It does not need to.
We don't really care if we are not level at 500M by the time we go beacon inbound over the BGW, but if we fly the approach procedure correctly we will be because the time from IAF to FAF exceeds 3.33 minutes. We are not allowed to land from this approach anyway. This is a beacon approach to the entire airfield at LFPB, not a straight in approach to a specific runway. We must join the circuit for the landing runway only after we identify the landing runway and identify where we must join it whilst tracking 071 towards the whole airfield from the Le Bourget Final Approach Fix at 500M. We must identify and avoid all the airborne AI traffic in our vicinity. We must remain at 500M tracking 071 towards the airfield until we have done all of that. Only then do we descend below 500M QNH to join the circuit at 400M QNH for the landing runway, even if the landing runway is 07. Real ALI crews were also required to achieve 200 KmIAS and to extend the GEAR fully and successfully before descending into the landing pattern anywhere.
We may NOT make a straight in approach QFU 07. This is the approach we must fly for all the runways at LFPB 1937-1943. The approach phase is followed by the circuit phase; whatever the landing runway. We are not the only aeroplane in the sky over Paris. We are not allowed to wander where we like at any altitude we like. Paris introduced ATC regulations in 1919.
When we arrive from Croydon the arrival fix is down at Villacoublay (HOL = 315 Kcs) which we will plan to cross lower than BRY because as we turn left over HOL the BGW is only 20 miles or so further on and already in range. This may seem a long way round but this arrival procedure separates us (laterally and vertically) from the outbound tracks and military airfields around Paris, so if we are lucky, and the cloud base is above 500M QNH, and the visibility is => 10 miles, and there is no holding delay, ATC may allow us to descend directly to 500M to cross BGW at 500M and then track 071 from BGW whilst trying to identify LFPB maintaining 500M.
Flight simulation is a 4D process with many operating targets most of which are 4D (altitude and time) navigation targets, many of which are not aircraft specific. The more carefully we plan and fly our target 4D profile the more realistic the simulation becomes. At modern major airports we may need to use an FS9 flight planning tool in conjunction with the real procedures from the internet;
www.calclassic.com/propliner_tutorial_charts.htm
to 'backdate' the modern real arrival to use vintage era terminal guidance navaids and plan our vintage era 4D arrival phase and our 4D approach phase before we ever descend to begin the 4D circuit phase. To increase the realism of our experience we must avoid descending far too soon to circuit altitude at random times and places, joining circuit patterns from random directions, or joining circuits at random IAS, and in random aircraft configurations. All pre war propliners are slow enough to fly standard visual circuits (see 2008 Propliner Tutorial Part 7), but they must be decelerated before joining them.
LFPB still has a Lorenz Beam on RWY 07. LFPB had a Lorenz beam in 1937 too. The only way to qualify for a straight in approach to 07 is to fly the beam approach instead of the beacon approach above. The minor difference in procedure is explained in the G.18V tutorials using Venice as the worked example.
In the modern phase of aviation history Le Bourget is so close to De Gaulle that LFPB inbounds are likely to be under radar control in 4D from a great distance, and since most are noisy public nuisances they are forced to stay much higher for much longer during the modern arrival phase.
FSAviator
Within navigating the Fiat G.18V it explains that the en route phase should proceed to the initial arrival fix, not the initial approach fix (IAF). Le Bourget no longer uses an NDB as its initial arrival fix, but a couple of minutes with an FS9 flight planner makes it obvious which NDB may have been used as the initial arrival fix for Paris arrivals from the south east in days gone by. The Paris area has approach aids whose range is 22 miles and arrival aids whose range is <> 70 miles. We look for the NDB to the south east whose range is <> 70 miles. That is Bray (BRY = 277 Kcs). Since the IAF is Le Bourget (BGW = 334 Kcs) (even in 2009) the arrival route is BRY - BGW. Time of descent is about 36 minutes before landing if cruising at FL180. Bray is fifty miles before Le Bourget. We receive BRY and navigate to BRY before Time of Descent. The GPS flight plan track ex Turin is to BRY, not BGW, not LFPB.
We plan roughly what level to cross BRY based on the level we must cross the IAF at BGW fifty miles further on where the arrival phase ends and the approach phase begins. For simplicity let's assume the minimum level at which we are allowed to cross BGW in 1937 - 1943 is 1000 metres QNH, (it may well have been).
Our speed (KTS) in descent will be somewhere around 2.5 miles per minute in a G.18V. On average those fifty miles will take 20 minutes. No precision is required. We always plan -500 VSI descents. 500 ft/min is 150 metres/min. So we plan to cross BRY at roughly 1000 + 20 * 150 = 4000M having cruised at 5500M. In practice we descend a little faster than 500 ft/min = 2.5 m/s but at not more than 3.5 m/s and we will be level at 1000M QNH some miles before BGW whatever the wind vector on that track actually turns out to be today.
Since BGW is only an approach aid its range is only 22 miles. We locate BGW by leaving BRY QDM 312M roughly on track to BGW. We will only start to receive BGW around ten minutes later and ten minutes before we reach BGW. During the last ten minutes of the arrival whilst we have BGW driving our goniometer we improve our tracking to BGW so that we arrive over the Initial Approach Fix (BGW) tracking 312 at 1000M QNH. At 1000M we have zero possibility of colliding with big masts. Paris had a rather well known big mast even in 1937. We won't collide with LFPB outbounds going south maintaining 700M QNH until well south of the BRY - BGW track either.
After we cross the IAF (BGW) we go beacon outbound. For the sake of simplicity we maintain our track of 312 for 30 seconds. We might 'realistically' clear ourselves to cross the FAF (also BGW) inbound at or above 500M. We descend immediately to 500M at between -2.5 and -3.5 m/s. It will take less than 500/150 minutes < 3.33 minutes to lose 500M. The instrument runway track is 071. After 30 seconds we turn left rate 1 to track 071 + 180 = 251. After we are established QDM 251 we go outbound for one minute. Then we reverse course to track inbound QDM 071. We do so at rate 1 which takes exactly one minute which is why it is called rate 1 (180 deg at 3deg/sec). Then it takes about another minute to arrive back at the BGW which has become the FAF. We concentrate on achieving a track of 071 to the BGW so that our track will be 071 after the BGW with no course guidance. QDM 071 will not take us to the threshold of RWY 07. It does not need to.
We don't really care if we are not level at 500M by the time we go beacon inbound over the BGW, but if we fly the approach procedure correctly we will be because the time from IAF to FAF exceeds 3.33 minutes. We are not allowed to land from this approach anyway. This is a beacon approach to the entire airfield at LFPB, not a straight in approach to a specific runway. We must join the circuit for the landing runway only after we identify the landing runway and identify where we must join it whilst tracking 071 towards the whole airfield from the Le Bourget Final Approach Fix at 500M. We must identify and avoid all the airborne AI traffic in our vicinity. We must remain at 500M tracking 071 towards the airfield until we have done all of that. Only then do we descend below 500M QNH to join the circuit at 400M QNH for the landing runway, even if the landing runway is 07. Real ALI crews were also required to achieve 200 KmIAS and to extend the GEAR fully and successfully before descending into the landing pattern anywhere.
We may NOT make a straight in approach QFU 07. This is the approach we must fly for all the runways at LFPB 1937-1943. The approach phase is followed by the circuit phase; whatever the landing runway. We are not the only aeroplane in the sky over Paris. We are not allowed to wander where we like at any altitude we like. Paris introduced ATC regulations in 1919.
When we arrive from Croydon the arrival fix is down at Villacoublay (HOL = 315 Kcs) which we will plan to cross lower than BRY because as we turn left over HOL the BGW is only 20 miles or so further on and already in range. This may seem a long way round but this arrival procedure separates us (laterally and vertically) from the outbound tracks and military airfields around Paris, so if we are lucky, and the cloud base is above 500M QNH, and the visibility is => 10 miles, and there is no holding delay, ATC may allow us to descend directly to 500M to cross BGW at 500M and then track 071 from BGW whilst trying to identify LFPB maintaining 500M.
Flight simulation is a 4D process with many operating targets most of which are 4D (altitude and time) navigation targets, many of which are not aircraft specific. The more carefully we plan and fly our target 4D profile the more realistic the simulation becomes. At modern major airports we may need to use an FS9 flight planning tool in conjunction with the real procedures from the internet;
www.calclassic.com/propliner_tutorial_charts.htm
to 'backdate' the modern real arrival to use vintage era terminal guidance navaids and plan our vintage era 4D arrival phase and our 4D approach phase before we ever descend to begin the 4D circuit phase. To increase the realism of our experience we must avoid descending far too soon to circuit altitude at random times and places, joining circuit patterns from random directions, or joining circuits at random IAS, and in random aircraft configurations. All pre war propliners are slow enough to fly standard visual circuits (see 2008 Propliner Tutorial Part 7), but they must be decelerated before joining them.
LFPB still has a Lorenz Beam on RWY 07. LFPB had a Lorenz beam in 1937 too. The only way to qualify for a straight in approach to 07 is to fly the beam approach instead of the beacon approach above. The minor difference in procedure is explained in the G.18V tutorials using Venice as the worked example.
In the modern phase of aviation history Le Bourget is so close to De Gaulle that LFPB inbounds are likely to be under radar control in 4D from a great distance, and since most are noisy public nuisances they are forced to stay much higher for much longer during the modern arrival phase.
FSAviator