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-   -   High On Final? (https://www.pprune.org/tech-log/612669-high-final.html)

poldek77 29th Aug 2018 20:48


Originally Posted by FlightDetent (Post 10235292)
The (pretty common) types I flew would as per FCTM go L/G down, mid-flaps and half spoilers at 180 knots to recover excessive altitude. Gives you between -1800, -2400 fpm in a straight line. If still too high (by 2000 ft above the platform, approaching the FAP - i.e. unrecoverable - let's imagine), the unfortunate decision to do a 360 would have you complete the full circle at 4000 below the target altitude. The obstacle clearance on the intermediate segment is 500 ft. Useless trick, that gets you nowhere but in trouble.

Sorry but I wouldn't like the idea of diving in such a mountainous area at 2000 ft/min or more for a glide slope which is already pretty steep, being busy with speed and configuration change... And I suppose that while orbiting you are still able to stop your descent at the desired altitude. ;)

FlightDetent 29th Aug 2018 21:16

Give it one more read including the post I was replying to. I think you'll find we're in a perfect agreement, ​​cześć.

172_driver 29th Aug 2018 21:53

I have seen a lot of armchair experts on here before but I think this one takes the cookie.

We know absolutely nothing about what went on in the kitchen (cockpit). In contrast to a steep spiral at 230 kts, thrust idle, flaps 5, speed brake out night IMC (as some may imagine).. it could just as well have been smooth sailing at 180 kts, flaps 5, vertical speed at 1000 fpm draging it in with thrust on a moon bright night in obstacle protected airspace.

As for reporting it... CHIRPing whatever that entails... give me a break. Disconnect and enjoy the fun of flying.

giggitygiggity 30th Aug 2018 01:23


Originally Posted by Capn Bloggs (Post 10235135)
I knew somebody would rip into me for that. Pull ya head in, Giggity. I never said I pass all responsibility for terrain clearance to ATC when they are radar-vectoring me. We also don't have access to radar terrain charts. Given the gung-ho attitude of some here "she'll be right, no hills around here that I can see", that's probably a good idea.

I don't understand then why you'd ever accept radar vector below MSA without the appropriate Radar Minimum Charts? If ATC clear you on a vector below MSA, how could you cross check the acceptability of that clearance without referencing it to a chart (SRA's excluded)? Surely, in that case you would have entirely absolved yourself of any terrain responsibility and be deferring straight to the last line of defence, the GPWS.


Originally Posted by Capn Bloggs (Post 10235135)
Unless you're on radar vectors or a STAR, you ain't going below the MSA with me unless you're at the IAF. Weather in the way? Hold or go to your alternate!

If you're doing you own thing though, as it appears here, John Wayneing an orbit below the 25nm MSA because you're high and in the area of the holding pattern is not on. You're either in the Hold or your not.

Can't see the relevance of "500sqm"...

They're obviously not in the hold. They could ask for extended vectors, would that be your preferred option? It may be more or less efficient than doing an orbit but achieves the same thing. ATC won't (shouldn't - that's why you cross-refrence your radar vectoring clearances from the chart just in case) clear them to a level below MRVA based on their current position/future position. You can request an orbit, a turn, 10 more miles, or a loop if you like, ATC will either approve it or deny it. If they approve it, then surely it is a vector which you should treat the same way you ever treat a radar vector, cross-refrence it's validity against your charts, which i've shown are available (that's not to say the guy in OPs post had them). If these charts are not available in your part of the world, then I am with you, where you operate, you shouldn't ever descend below MSA unless flying procedurally.

The relevance was that 500sqm is a very large area, there will be many times that weather might appear inside one of these 25NM/90deg arcs. In that case, i'd assume most pilots would request a deviation to one side or another after first checking whether it was safe (terrain wise) and then passing that request onto ATC. ATC will either approve or deny that request based on the terrain, airspace, traffic etc. Using Flight Detents RNAV STAR 28 chart, if there was stationary weather at ETPAL i'd genuinely like to know what you'd do? Would your only option be to request direct to the hold and stay 8300ft till you get there, then descent to 6000ft in the hold and fly the approach after a couple of laps of the hold (assuming there was no other compatible procedure, for whatever reason)? I don't mean to be obtuse but I can see this as the only solution, at which point ATC will tell you to stay at 8300ft and wait a further 20 minutes so the other aircraft can pass underneath you.

In reality, every time I've flown this approach - although it's been a while - it was via that RNAV transition and ATC just issue speeds for spacing. We've simply planned to fly the thing conservatively and don't end up with this dilemma.

Escape Path 30th Aug 2018 01:25


Originally Posted by poldek77 (Post 10236730)
Sorry but I wouldn't like the idea of diving in such a mountainous area at 2000 ft/min or more for a glide slope which is already pretty steep, being busy with speed and configuration change... And I suppose that while orbiting you are still able to stop your descent at the desired altitude. ;)

I had forgotten about the steep G/S! I initially agreed with "intercept from above" as another option to what is being proposed/talked about in here. However, intercepting from above (in my type at least) is sort of a last resort, the altitude difference can't be too much or you risk not intercepting at all, and this is for a 3 degree G/S. The extra degree certainly reduces the altitude margin to be able to perform that particular manoeuvre successfully. Maybe too little margin and perhaps an even greater risk of creating a scenario for an unstable approach. The higher up you can correct your mistakes, certainly the better. Darting (I'd consider darting going down a G/S with altitude to spare at 180ish kts) down like that is certainly reducing margins for correcting mistakes. And it reduces even more by every foot you continue to go down.


Originally Posted by 172_driver
We know absolutely nothing about what went on in the kitchen (cockpit). In contrast to a steep spiral at 230 kts, thrust idle, flaps 5, speed brake out night IMC (as some may imagine).. it could just as well have been smooth sailing at 180 kts, flaps 5, vertical speed at 1000 fpm draging it in with thrust on a moon bright night in obstacle protected airspace.

Agreed. It certainly could be just a case of not too much altitude to be lost, enough to lose it on a 360 in a controlled (i.e. speed and rate of descent) manner.


Originally Posted by 172_driver
Disconnect and enjoy the fun of flying.

Certainly. I think enough evidence has been provided to hint at the possibility of a safe manoeuvre if done with all important things considered.

Chesty Morgan 30th Aug 2018 09:57


Originally Posted by Capn Bloggs (Post 10235135)
Unless you're on radar vectors or a STAR, you ain't going below the MSA with me unless you're at the IAF. Weather in the way? Hold or go to your alternate!

You know you've got windows for a reason...?

Capn Bloggs 30th Aug 2018 10:46

It's your turn, alright...


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