TERPS circling protected area

[aterpster]

Dan Winterland:

Even at 2.3 miles radius, the circuit height is 1100'. At the PANSOPS radius of 4.6 miles, you will have to fly round finals at about 2000'! It's just not feasible as the hill in question is on the centrline.

It's only a matter of time until the new, much larger TERPs CTL criteria catches up with them.

[aterpster]

OKC465:

My memory didn't do me well on that AAL CVG crash.

I guess 121 was different. I had four rating rides during my career. The first two were in the airplane (1967 and 1969) because the sims weren't qualified. The second two were all sim (1983 and 1986.) We didn't do any CTL either on the rating ride or on any PC.

My cerificate wasn't marked either. I understand they started doing that sometime after my last rating in 1986.

[Tee Emm]

The Australian Air Services AIP has one of the most misleading paragraphs I have seen on the conduct of circling approaches and this is taken from ICAO. Discussing when to descend below the circling MDA for landing it says:

"While complying with (visual obstacle clearance) ...by day or night....at an altitude not less than the MDA, descent below the MDA may only occur when the aircraft intercepts a position on the downwind, base or final leg of the traffic pattern and from this position can complete a continuous descent to the landing threshold using rates of descent and flight manoeuvers which are normal for the aircraft type and during this descent maintaining an obstacle clearance along the flight path not less than the minimum for the aircraft performance category until the aircraft is aligned with the landing runway."

It means at night the pilot must be able to see the ground ahead and below in order to maintain minimum published terrain clearance until on final.

While the AIP is clear in the intent that the pilot must be able to gauge his height at night above terrain, he will almost certainly be unaware of the position of the critical obstacle that dictates the MDA. Therefore, to plan on deliberately descending below the circling MDA merely to suit the ideal glide path profile downwind, or base (which has nothing to do with terrain clearance but more to do with profile handling) - has led to unnecessary risk taking because once the pilot has left the published circling MDA he is entirely responsible for his own obstacle clearance. Unless the pilot is familiar with the position of terrain (such as over water or flat ground) at night, then it is wise to stay at the circling MDA until established aligned with the landing runway.

[Old King Coal]

There are some fundamental & substantial differences between the TERPS & PANSOPS Circling procedures!

See: http://www.skybrary.aero/index.php/C...S_and_US_TERPS

[aterpster]

Tee emm:

While the AIP is clear in the intent that the pilot must be able to gauge his height at night above terrain, he will almost certainly be unaware of the position of the critical obstacle that dictates the MDA. Therefore, to plan on deliberately descending below the circling MDA merely to suit the ideal glide path profile downwind, or base (which has nothing to do with terrain clearance but more to do with profile handling) - has led to unnecessary risk taking because once the pilot has left the published circling MDA he is entirely responsible for his own obstacle clearance. Unless the pilot is familiar with the position of terrain (such as over water or flat ground) at night, then it is wise to stay at the circling MDA until established aligned with the landing runway.

If the MDA is too high for the pilot to remain at it until turning final and then make a normal descent for landing (while remaining within the lateral limits of protected airspace) then descent below MDA must necessarily occur on base leg or perhaps even late downwind.

The sensible answer is to circle in such circumstances only at an airport and to a runway where you have current and good local knowledge. Otherwise, you are asking for an accident.

Why is the MDA for CTL so high at some airports? Usually big rocks, sometimes a tower. But, a tower can usually be avoided by the designers by restricting CTL to one side of the runway.

Contrary to some folks opinions, CTL can easily become a high risk operation, more so at some airports than others. Less so if the pilot is very familiar with the airport environs and is at the top of his game.

[BOAC]

Originally Posted by aterp

The sensible answer is to circle in such circumstances only at an airport and to a runway where you have current and good local knowledge. Otherwise, you are asking for an accident.

- Concur- an 'incident' I recall many years back at RAF Leuchars in Scotland where a visiting Canberra flew a left-hand night visual circuit on R09, mantaining a direct, clear line of sight to the threshold, and actually rubbed his wingtip tank on the side of Lucklaw Hill (fortunately the side sloping towards the runway.......) half way around finals.................................

[aterpster]

There are many IAPs in the mountain areas of the U.S. where the circling MDA is very high, not because of rocks in the CTL maneuvering area, but because of penetrations of the standard missed approach surface. In the latter case the pilot has lots of clearance in the CTL area, but this isn't really apparent unless the pilot is familiar with the airport.

[172_driver]

Where I used to fly, KSEE, was a good example of a relatively high CTL MDA. Admittedly, I just flew a light twin in there but I believe even the bigger jets (Gulf 5, Falcon 900 etc.) had to start their descent on downwind to manage their profile. Overshoot the final for 27R, you would hit the biggest rock in the vicinity of the field. Also if a balked landing was to be executed the published missed approach procedure would not be a very good idea since it would take you approximately right over the highest point (Cowles Mountain for the locals) direct to MZB VOR. Runway only 1615 m. Easy to paint yourself into a corner on a bad day, I can imagine. A basic VFR pattern south of the field might be the best idea. Local knowledge about the terrain is certainly useful.

Are there any procedures laid out at all for balked landing go-arounds below MDA during CTL? Missed approach procedures do not really take that into account, do they?

[aterpster]

172 driver:

Are there any procedures laid out at all for balked landing go-arounds below MDA during CTL? Missed approach procedures do not really take that into account, do they?

Nope, you're solo. The U.S. AIM does discuss it. In some cases they advise reverting to the ODP. That may result in a lot of problems including a climb gradient problem for a small airplane.

[BOAC]

Any more than they provide G/a patterns below DA on an ILS. Salzburg is a good example (LOWS) where the g/a for the special (200'DH) ILS is quite different to the higher 'normal' ILS due terrain.

Don't forget that in the process of manoeuvring onto the g/a for the 'other' runway if you wish to escape (visually, of course..............) you will be gaining height. Also worth remembering that there is nothing to stop you joining the visual circuit or another 'circle', but that if it is night, it is not a good idea to turn onto the g/a track OR downwind until you are at circling minima.

[4dogs]

Received Wisdom?

Centaurus,

Received wisdom is you don't commence descent below the circling MDA until lined up on final hopefully with a VASIS or PAPI available.

I presume you are talking about TERPs circling. Or is that what you are teaching for PANSOPs?

Stay Alive,

[Denti]

BOAC, the only difference in LOWS is a max speed and advise until which altitude you cannot accelerate during the turn, isn't it? Depicted groundtrack and procedure wording is the same though.

[BOAC]

LOWS - I have not looked at the plates since 2007/8 but then there was a different ground track. It must have changed.

Just checked - yes, they appear to have 'standardised' all approach g/a tracks since then apart from different speeds/bank (so I reckon it is still valid) - I always briefed the 'CatIII' g/a for a baulked landing.

[Tee Emm]

If the MDA is too high for the pilot to remain at it until turning final and then make a normal descent for landing (while remaining within the lateral limits of protected airspace) then descent below MDA must necessarily occur on base leg or perhaps even late downwind.

Surely the solution to that situation is to divert - since descending below the circling MDA at any point other than within the protected area in the final approach splay, is potentially dangerous - unless the pilot can ensure legal terrain clearance for the category of aircraft.

[BOAC]

Don't miss the rest of that post?

The sensible answer is to circle in such circumstances only at an airport and to a runway where you have current and good local knowledge. Otherwise, you are asking for an accident.

[Denti]

We need just regular training in the simulator, for example this year we do our CAT III training in SZG. But it is not even required every year.

[Tee Emm]

Received Wisdom?
Centaurus,

Quote:
Received wisdom is you don't commence descent below the circling MDA until lined up on final hopefully with a VASIS or PAPI available.

English Dictionary -Geddes & Grosset - New Edition. Page 352.
"Received"...ad. accepted, recognized'

[aviatorhi]

Slight hijack of the thread here, but my types are all unrestricted (no DAY VMC ONLY circling limitations). Now, if I am flying with a FO who does have this restriction on their certificate am I now limited by their certificate?

[9.G]

Av. I'd say you're to go with the most restrictive crew authorization. That's one of the reasons why Chinese require no circling restrictions on license. Same story goes for both pilots having unrestricted licenses but one not being qualified for the airdrome. Best example I can think of being CIA. VOR A is a circling approach using prescribed tracks.

[bubbers44]

Good old common sense will get you to the runway once in VMC conditions. Making restrictions like staying at MDA until turning final only causes you to be high and unstabilized. Any decent pilot can determine in visual conditions where he should be to make the approach work properly. Don't make something easy hard.