Hi there, let’s see if some seasoned or RL pilot can help me.
I am trying to follow the RNAV procedure in the Jeppesen Charts (via Navigraph subscription) to land the FBW A320NX in the “Worlds most difficult airport” (?) (Paro, Bhutan).
If I read the chart for RNAV15Z, it is as follows:
According to the procedure, I understand that I should be at PR816 at 13,800 ft, 145 KT and then descend on a 3.5º angle.
When I try this, I end up much above the airport, so it is impossible to land.
Actually this makes sense (from the chart), because PR816 is at 9 Nm from the airport. At 145 Kt this is 3.7 minutes flight time. At ca. 900 ft/min descent (as published in the chart for this speed), I will end up at 13800 - 3.7 * 900 = 10,400 ft at the airport.
This is 3,000 ft too high (runway is at around 7,400 ft) and it matches my experience with MSFS.
So,
Either the chart is wrong (unlikely for a Jeppesen)
Or I am interpreting it not right, and the actual flight path angle should be around -7º instead of -3.5º
Or I am missing something, and may be the purpose of the chart is really to get 3,000 ft above the airport, and them to do some maneuver (in manual flight mode) to actually land.
If anybody has tried this approach, I will appreciate any insight (BTW, I tried also another RNAV approach on this airport, leading to RWY33, and the result was also the same, I always ended too high when reaching the runway).
I’m not familiar with the airport but from the chart it looks like the missed-approach point is pretty much over the runway (PR808) so it seems correct. The rest of the chart will probably tell the rest of the story but it seems you’ll be expected to perform a “circle-to-land” for either runway becoming visual at or before PR808 or otherwise execute a missed approach. The reason for this construction is most likely terrain and obstacles preventing you to fly a proper straight-in for the runway. This approach is designed rather to let you approach the airport instead of the runway.
What I do find about Paro approach is that you need to fly close to the terrain as you approach. The path that the chart is showing is pretty okay. But the glideslope is still too high. You can see even in the charts that the 3.5º is bringing the line to still be high when it gets to the runway. So you might need to descend a lot steeper than that but keep an eye on the terrain, make sure you’re clear of any hills and mountain peaks around you.
I find that approaching to RWY 33 is the easier one. The valley is longer and more straight allowing you to fly lower and easier to manoeuvre for the final landing. Like my flight here that I did months ago.
Are you sure that’s how the approach is meant to be flown? Seems to me a circling is required from the missed-approach point for landing. Its not meant to be flown steeper, certainly not under instrument conditions. As can be seen in the screenshot below, it clearly shows a visual segment after the missed-approach point, passed the runway:
The note about visual conditions needing to be met at the DA confirms that. The operator possibly needs to establish additional procedures, like go-around after missed-approach point has been passed and circling initiated, engine-out procedures etc.
VQPR can’t be approached in instrument conditions when you’re close… at least not in MSFS. Tried that before, either I crashed into the mountains, or I get disoriented very quickly. Even when it’s on a cloudy conditions, it’s better to just divert to another airport. The airport has no lights, no localiser, so even on RNAV approach, I just use the RNAV approach it to position the aircraft before disengaging AP and fly manually down to the runway visually.
That’s why you need a special license to fly into VQPR in real life… Only captains can get this license, and first officer are not allowed to fly this approach. There’s only a dozen pilots in the world certified to fly here. Which I doubt any one of them is here in this forum to give the proper answer on how to fly this approach.
Yes like any CAT-C airport, the FO can likely get and need the “license”, but they are not allowed to be the flying pilot. At least that’s often the rule for CAT-C airports.
I have flown many to CAT-C airports, this is not one of them unfortunately. There are minima (DA) for this approach, so whether a good idea or not, it is possible to approach the airfield in instrument conditions as long as you are VMC at DA for visual maneuvering. The vertical path is designed this way for a reason, I don’t have the charts myself in my EFB (NavBlue) so I can’t check. I don’t think the approach is meant to be flown straight-in.
Normally the operator is responsible to built contingency procedures, describe higher minima based on the aircraft performance etc.
Thanks to all for your replies…
I think you are right, and that the procedure which I posted is intending to leave the aircraft at decision height, 3000 ft just above the airport, and then probably circle to land would be needed.
Nevertheless, the valley is quite narrow, and there are many obstacles, so I am not sure an Airbus can do this (at least in MSFS).
The other approach, which @Neo4316 pointed out (the “Star Wars Death Star trench mode”) seems to work in MSFS, if flown in manual mode. I have repeated it several times and finally managed to land in RWY15, although it must be scary as hell IRL.
On the other side, my interest in this airport was originally sparked by this video: https://www.youtube.com/watch?v=SbLHah4XUwk
Here you can see a real-life landing in RWY33 from the cockpit, and there is no circle to land, but rather what seems to be the “Death Star Trench” way.
I will keep practicing just for fun, I am beginning to use the amazing “Flight Control Reply” app, and with it is very easy to replay you attempt, and to start piloting yourself from any given point during the playback, to try to improve the outcome…
It is an interesting one, of course when you are visual you can do as you like, given sufficient ground clearance is maintained. The main problem with this approach is that it cannot be flown as a “stabilized approach” and therefore, amongst other reasons (terrain obviously) requires special training. This airport is a category C airport which generally means specialized training is required in a simulator or having approached the airport as an observer (jump seat) and the captain must be pilot flying. For some airports it might be even more strict (likely the case here).
The published approach, like what Jeppesen has published does not take into account all performance categories, also it doesn’t approach a specific runway, it allows to approach the airport rather than the runway. I found the full plate on the internet just now and it says circling prohibited. So likely the idea is to follow the approach when in IMC until VMC, after which deviation from the glidepath is required in order to land, which can be quite steep.
Obviously you can’t do that in anything bigger than a Cessna, definitely with an A320 you are not gonna dive to loose 3000 ft quickly before the runway threshold, but that’s not Jeppesen nor the CAA publishing those instrument procedures their problem. Its up to the operator to establish more strict minima or procedures (maybe visual approach only?), also the operator is responsible for establishing escape routes and climb-out procedures for engine out situations, procedures for go-around / balked landing etc. In short an engine failure should be taken into account at any point during the approach and the aircraft must be able to climb-out safely. The operator has quite a lot more responsibility and much more planning, training and approval is required before flying to such airports. With operator the airline is meant of course unless flying a private GA aircraft, there the pilot is considered as the operator.
By the way a common misconception is that an aircraft, at missed-approach point, should still be in a position to land when runway comes into view. This is definitely not always the case, of course in 99% of cases it is, on most instrument approaches, at DA the runway is in front of you and you are on a direct path towards the aiming markers. There are cases where, when at the missed-approach point there is no way the aircraft is in a position to safely land and a go-around should therefore be initiated. I have seen cases in real life where the MAP is even behind the runway without the ability to perform a circle-to-land. So when approaching minima in such case, apart from considering if sufficient visual references are available to continue approach, you should now also consider if the aircraft is in a position to land safely.
Thanks so much for your detailed explanation.
This is one of the reasons I love MSFS and this forum.
In the meanwhile I succeded to make a not-so-terrible landing at RWY15 with the Airbus.
I will try to post a video later, but in principle the technique used is:
Follow the published procedure (chart above) until PR816. Get there at 145 KT, Flaps 2
Auto-pilot off, full configuration (gear + full flap), thurst iddle and descent as fast as possible trying not to overspeed (I did not fully succeed in that, probably some airbrake would have been needed)
When the airport is on sight, target the runway, which implies flying very close to an obstacle just in the way. Anyway, this seems to be the procedure of the Air Bhutan guys, as they say in the Youtube video I linked before that they disconnect GPWS because they have to fly very close to terrain…
Configure earlier maybe, on an approach like this configure early and go slow. You need all the drag available to loose the altitude and stay on speed. Not sure if you can use air brakes on the Airbus when in landing configuration. On the Embraer I fly there is a steep approach option where a couple of multi-function spoiler panels open to a certain angle for a neutral control column and depending on control inputs deploy or retract slightly to maintain speed (retract pulling the nose up, deploy further pushing the nose down), would be a useful option for this approach, I know the A318 has steep approach capability.
Yes especially if the airport is not in the terrain database or extreme cases like this that is often the procedure but requires extra vigilance on the part of the flight crew (which is needed anyway flying this approach). I don’t think the airport is even in the terrain database as there isn’t a proper solution for modifying the Terrain Clearance Floor (TCF) and preventing nuisance alerts for an airport like this.
They likely turn off the “enhanced” functions of EGPWS which use the onboard terrain database such as the Terrain Clearance Floor (TCF) and Forward Looking Terrain Avoidance (FLTA) while keeping the basic GPWS active which only uses the radio altimeter (looking down only). Or maybe they turn everything off altogether .
In instrument conditions it would be useful to have the EGPWS working though without nuisance alerts, I don’t know about the Airbus but the aircraft I’m familiar with the terrain display is also removed when inhibiting the EGPWS as it is part of the system.
at 03:10 comes the scariest part (the terrain sweeping approach)
My computer is 4 years old and I use a 1050 2GB VRAM card, so the MSFS quality is far from perfect. I’ll have a new machine in the next days, so hopefully I will have to reshoot that.
Also, forget the silly soundtrack which is a family joke - it’s the music from a Pink Panther videogame I used to play with my son when he was a kid, something like twenty years ago…
Cool! If I were you I would configurate early, ditch the RNP approach (at least the vertical path) when visual and stay in the valley. Also that last part, when staying more to the left in the valley you could fly a more suitable and stable descent path towards the runway instead of diving towards the runway flying straight-in over that little hilltop. It requires some low level maneuvering to get lined-up with the runway, but I think its a better option and safer compared to diving towards the runway on a late stage during the approach. I thought I saw the same in that real world video of the approach?
By the way what is that fence doing there so close to the taxitrack? Looks like you are almost poking the wingtip through it.
Thanks again, @anon50268670!
Actually, I ditched the vertical path approach, everything since gear-down is 100% manual.
When I tried to circumvent the hill instead of over-flying it I did not succeed, probably I am not skilled enough (also, I use the Airbus TCA stick with the left hand, as it would be in the cockpit - captain position- , and I am right-handed so I am not so comfortable with this).
About the fence, I assume that this taxiway is intended only for smaller craft. I imagine the Airbus would turn on the runway end, and taxi back via the runway until close to the terminal.
I think there is one of the “Landing Challenges” in MSFS (using the stock Airbus) which is Paro RWY15. I will check that as well…
Its more difficult in a sim compared to real life as you can easily look around and determine the bank angle required and adjust where necessary. Maybe in VR it is easier? Its a better option than flying over that hill as it is very easy to pick-up speed which needs to be bled off before touchdown or become unstable on thrust setting before touchdown.
However, there is no way I can get even close to the runway with this…
Also, the landing challenge is with the stock A320Neo, which behaves completely different than the FBW 320 which I am used to, and I do not have the throttle calibrated for it.
Keep in mind that this is an RNP AR “Cloud Break” procedure. Its not specifically stated in the Jeppesen charts, but it is stated in Bhutan’s AIP document with its accompanying navtech style charts that you can find via google. Regardless, this is NOT an approach that flies you on a nice 3 degree path towards a runway. Once you break through the clouds, you are supposed to maneuver visually.
I’m not exactly sure precisely how this actual approach is supposed to be flown after “cloud break”, as most of the youtube videos I’ve found in the past are based on a dated VOR approach that requires you to fly over the airport from the south, make a course reversal on the first valley to your left by turning towards it, then right hand tear drop descending turn (to ~9500’), aim for a temple in front of you, do a steep 30 degree bank right bank towards a small house (Mr. Smith’s House), and then line up with the runway with a tight left turn after just clearing the house.
Normally when I do this approach in the sim, if I can breakout the clouds and be visual by PR816, I can disconnect the autopilot, stay on the lateral path, pitch the nose to 0 degrees on the PFD, and maintain about a 2000 fpm descent (fully configured of course). This puts me on a nice profile that puts me at about the right height when flying towards the temple (reference some youtube videos on what the picture should look like). I don’t know if this is actually how they do it or not (they do literally fly towards a temple and make a hard bank for a house though!), but it certainly saves a lot of course reversals, which you would likely have to do after crossing overhead the field.
Now, if you are not visual by the FAF, then you can continue down on the published path. You can normally do a course reversal in one of the valleys after crossing the runway, but you will need to make another (like the one I described above) to line you back up with the temple for runway 15.
Hmm, with a commercial aircraft? Don’t think this is the proper way to fly these approaches. When breaking out of the clouds and not in position to land safely from an energy management perspective or passing the missed approach point, whichever occurs first → execute missed approach. I doubt they screw around with an A320 in the valleys there in real life.
The operator might prescribe something like that, we had a visual engine failure climb-out procedure at Innsbruck for example in which we had to follow the Inn valley until so QDR and DME (widest point) before turning around and fly back down the valley. But this seems a little more critical compared to Innsbruck.
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