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Behind the Screen : April 2021

 

What do you consider the hardest thing in a procedure to fly in the X-Plane Simulator...  put your hands up!  Most will say the landing, and that would be a good answer, as getting the landing right will give you a huge satisfaction and a smile on your face, get it wrong and your faced with a huge X-Plane particle fire and usually a broken aircraft. But the landing procedure is not the one thing that can totally ruin in a simulation... in let us say a perfection "block to block", absolute "Nailed it" getting it all right scenario.

 

On landings they can range from the very tricky (i.e. windy), to bouncy wouncy...  "lucky there" and then getting away with it jumpy or hoppity hop landings, but those sort of flight elements are natural as well in the real world as the loads of YouTube video's show.

 

The hardest procedure I think and the one that can totally ruin a simulation as per a reflection on real world flying, is the descent from your cruise altitude to the circuit phase... tricky, that "you must be joking".

 

But it can be a horror if you don't get it right and it also can make an absolute and total fool of you, and even worse, actually make you have to do the dreaded "Call off" and circuit back around to a landing.

 

Here is the problem. Get the descent wrong too early and you will spend an eternity at a low cruise altitude and flying at a slow speed before you (finally) enter your landing circuit, the opposite and the worse is the about face situation, is coming into the last tight turn too high and you are simply "up there" and the runway is "way down there", so you are faced with that dreaded go-around, and having to accept a very embarrassed about face of having poor piloting and judgement skills.

 

Most will be shaking their little know-all heads and saying things like "Know the 30 nautical mile, to 10,000ft rule" for the correct descent, or use the Altitude Target Marker in the Primary Flight Display. But both those aspects are quite and actually still ambiguous when deciding your descent profile. First the Altitude Target Marker. the ATM is a brilliant tool to set your altitude right at the entrance marker of starting your approach circuit, and usually correct of being correct at the point of altitude. But annoyingly a lot of the ATM's will consistently move or mostly stretch as you descend if your speed changes, so you are required to readjust to the marker, there is a change in speed to still reach the correct height at the right time...  above all though it is the perfect descent tool.... but the ATM tool is only available on certain aircraft to use.

 

The 30nm by 10,000ft rule is however correct if you get your descent speed precise, but there are many other factors. Wind and the type of landing circuit you are entering...  the best is a full complete landing circuit that mostly allows you to fly past the airport in a parallel course with two 90º turns into the final approach. So your aim is to get to the correct altitude, either 8,000ft or 6,000ft along the start of the parallel circuit. These approaches are also good for flattening out the altitude corrections and speed changes, because you have the time and space to adjust the aircraft (flaps and speed) to enter the final approach, so they are always my pick if possible on any airport approach phase. The hard ones are the direct in approach were as you don't have the time to do these procedures, and sort the aircraft out. Obviously most users would prefer the direct in and land approach pattern because it shows off their flight jockey skills, but they are seriously hard work in a busy cockpit, and worse you have no backdoor if you get your descent calculations wrong.

 

On most approaches you can't trust the flightplans or STAR (Standard Terminal Arrivals) approaches either. A lot of STAR approaches put you in far to close in the final turn to the start of the ILS beams to make a decent connect, plus your altitude BETTER be absolutely spot on or you will simply miss, flyover or not connect to the beams...  a trick that I do is go well below the beam at say a 1800ft height into the start at the usual 3,000ft height at the start of the beam and this will give you time (and space) to readjust the aircraft's heading after the tight turn-in to the ILS cone, and then connect later to the beam more than usual down the slope. Also to make that last tight turn in, then reduce your speed to at least the most second last or even the full flap settings, this reduces the going out too wide on the turn with a tighter and slower turn.

 

Another trick is to use the RNAV approach charts to readjust your approach. If you look at RNAV approaches they usually start the approach phase further out than the tighter STAR approach, and then add in a few more extended waypoints to the flightplan, to make the final turn (to the runway) and put you a bit further out from the ILS approach cone. I don't think this is actually cheating, because if you are doing the RNAV approach, then you would follow these waypoint procedures anyway. In most cases I do "always" edit these final approach waypoints to get my approach totally correct, certainly when there are two tight parallel runways that are set too close together, as again get the final turn wrong and you are flying down the wrong chute (oddly Johannesburg OR Tambo approaches always do this).

 

But the calculations from TOD or "Top Of Descent" to the start of the approach phase are critical in getting that absolute perfect "Block to Block" experience. First, I never use the noted flightplan TOD marker, it is usually wrong if you want a real life profile landing... most would say "what, what...  and what!". But following, I found most marker TODs required a very steep descent of excess way of 2,000fpm, plus the express speed that steep descent causes. I accept that my TOD is usually about 20nm before that official descent point, but I will wear that aspect to get it totally right in coming down realistically at the right descent rate and hitting my altitude marker. 

 

Another trick is using the Airport VOR effectively. If you reach your TOD point and check your flightplan distance it may show something like 93nm to the runway, but check the airports actual VOR distance position and it may say a completely different story in say the airport is in being only 50nm away, in other words you can actually see the airport out of the window (usually at night) and you are flying at a speed that is far higher and you are closer to your runway than you actually think you are. Get it wrong and you will certainly reach the airport sitting too high or go too long.

 

Then comes the difficult descent speed...  remember the speed in any long approach is absolutely critical to get right, and again I veer to the safe side. When changing to a descent speed I usually set the Mach down to m.63, which should translate to 250knts when at the transition altitude. The aircraft should hold the mach number until you switch it over to the knots at the correct speed you want, although a lot of Airbuses switch from m. to knts as high as 30,000ft...  but most of the numbers of say m.70 will cross around 25,000ft. Okay it does look like I am a total control freak, and real life pilots may totally abhor these sort of flying skills.

 

But you are looking at a changeover position speed of around .70, or slightly higher depending on the size and weight of the aircraft. Obviously I abhor using Airbrakes, but they are sometimes required to meet the required altitude and at the correct speed. You know if you are on the right altitude and speed if you start the STAR entrance point at around 12,000ft-10,000ft (officially it is 10,000ft in the US),If you get your calculations right, and you should hit the numbers spot on to get that perfect set target of position and speed at the right place at the start of the approach phase, once there, I then reduce the speed and then start another 500fpm descent down usually to 5,000ft to 4,000ft before the last two final slow turns or follow the approach charts just on the money, if it says 8,000ft then be at 8,000ft, but change height the moment you leave that sector and get down to the next official altitude.

 

Most of the notes here would say that I fly slow, certainly you could hold a 300knt speed on the start of landing circuit phase, and even stevens and go for 280knts, of which is the initial approach speed I use quite regularly, but slower also means more time to react, and more time to get your procedures correctly, and more importantly if something goes wrong you then have the time and space to fix it. Oddly when I compare my gate to landing times with real world times, I am usually within a very close margin, even only around 3-5 min each side of the real service times (so I must be doing something right), Once I flew LON-HKG and landed just 2 min ahead of the real BA service, something I still let everyone know about... 

 

The tricky ones can be the turbo-props, you set a slower speed and then the descent rate, but then the aircraft simply won't descend past say 500fpm, so you are simply not going down to the plan, in most cases you override the automation and set a negative trim pitch to "get that nose down", but in the time you have been wasting or wrestling with the aircraft, you are now too far past your descent point and now have to take a steeper dive to meet the altitude target (way)point. I hate that, I really do.

 

So I am not afraid of flying slow or say 250knts or even as slow at around 200kts (say a B737/A320) along the parallel circuit, it gives me time to adjust speed and height to get into the position of the final approach perfectly.

 

A lot of this descent planning goes on even before I even leave the departure airport, I check the approach charts and my assigned approach (STAR or RNAV) and make sure every waypoint is covered and correct. You would be surprised how messy (I.e. Rome) the approach waypoints are situated and following them can not guarantee a perfect approach path, and even if flying a manual approach circuit.

So any FMS flightplan that can't be checked at the final approach phase can cause havoc when you get there...  this is why I rile so much against the poor Laminar FMS tool, because it is so out of date and too hard to check or fix your flightplan at "that end" of the flight.

 

Obviously the calculations are Distance x Altitude x Speed x Current Weight x Wind Direction, you can adjust (Speed and Vertical Speed) on the descent phase to keep yourself on the numbers, but the vital point in the flightplan is the TOD, and of when to descend in making sure you don't go to long or too short...   it is a very tricky procedure and even an art form, but totally fulfilling to get absolutely perfectly right and the need to do your homework before you depart to make it perfect the other end.

 

This months Behind the Screen is a few days late, sorry about that, but the exceptional JustFlight BAe146 review was a huge one to cover and complete for the review. There was a lot of ground to cover, not only working out all the systems, but on how they actually work, then put that into actual flying practise. There is no doubt on how really complex simulation is today, or the real depth of the systems. I will be very open and say I doubt I could actually cover everything on this or any these high grade study aircraft in the very short period (say a week) on from a release, the 146 will take actually a few months to get my full ticket on the aircraft, but that is part of the deal, and part of why simulation is so very appealing and gives you the huge satisfaction when you master it...   it was like cramming in for an exam, did I pass?

 

See you all next month.

 

Stephen Dutton

5th May 2021

Copyright©2021 X-Plane Reviews

 

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I’d argue the really tricky ones are the older jets like the FJS 732 and 727. With all or most of the flap hanging out and the slower spool up on the older jet engines more than a little care is needed to keep speed and descent right. Step into the Toliss 321 or Zibo and you’ll appreciate how far aviation has come in the past few decades.

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