Originally Posted by Algol
No mention was ever made to me of a 25kt tailwind built into the design (this company was PANS-OPS).
This is from PAN-OPS DOC 8168 "Volume II Construction of Visual and Instrument Flight Procedures"
7.2.2 Parameters
The parameters on which visual manoeuvring (circling) radii are based are as follows:
a) speed: speed for each category as shown in Tables I-4-1-1 and I-4-1-2 in Chapter 1;
b) wind: ± 46 km/h (25 kt) throughout the turn; and
c) bank: 20° average achieved or the bank angle producing a turn rate of 3° per second, whichever is the lesser
bank. (See Figures II-4-1-App A-2 and II-4-1-App A-3 in Part II, Section 4, Appendix A to Chapter 1,
“Parameters for holding area construction”).
7.2.3 Determination method
The radius is determined using the formulas in Section 2, Chapter 3, “Turn area construction”, by applying a 46 km/h
(25 kt) wind to the true airspeed (TAS) for each category of aircraft using the visual manoeuvring IAS from
Tables I-4-1-1 and I-4-1-2 in Chapter 1. The TAS is based on:
a) altitude: aerodrome elevation + 300 m (1 000 ft); and
b) temperature: ISA + 15°.
The 25 kts is built in. TERPS also has 25 kts built in however there are other differences.
Originally Posted by vilas
The airbus procedure is to start levelling off at height 1/10th of the vertical speed at the moment by push to level button, which is appx. 70 to 90ft before the MDA so you level off at circling MDA and well above NPA MDA.
Not all Airbus have a level off button, to achieve this on a lot of A320s you would press the V/S, on the wide-bodies there is an ALT button or you can press V/S.
Originally Posted by lederhosen
Anyone care to suggest what descent rate you need in Dalaman if you turn base at 2400 feet at three miles. The fifty feet increment presumably could be corrected downwind, but I am struggling with achieving a stabilised approach from high minima like this one.
Your question has gone unanswered basically because there is no stable way to do what you are asking. You will be at 2300 ft above the runway, so you will want to start descending at 2300/318=7.23 nm track mile from the threshold, about 15 seconds after passing abeam the runway at 750 fpm at your 150 kts.
Practically you cannot do this in marginal conditions as you will not have the runway environment in sight late downwind. In marginal conditions the procedure while technically legal, is not not practically smart. In marginal conditions do the VOR-DME3 from the NW and "circle" to final where you can continuously have the runway environment in sight.
If you are actually flying down the ILS to do a cloud break, and your intention below the cloud ceiling is not to circle but to conduct a right hand visual circuit, as long as your company permits this, ATC clearance, required visual conditions etc there is no reason why you cannot descend down to 1500' on crosswind or downwind. Then fly a normal 1500 ft circuit to land, back to something sensible and you are used to.
Originally Posted by RAT 5
When you are about 90degrees to go you will be entering the +/-30 degree cone to the centre line where you can start a visual descent.
There is no ICAO requirement to be within 30 degrees of the centreline, I have seen in the order of 13 different company variations for when a descent may be commenced, the ICAO requirement is to keep the runway environment in sight. On an airliner with the cockpit viability the way it is, gives rise to this sort of sensible constraint being put in place. In the Dalaman example raised above the VOR-DME3 is offset by 40 degrees making it a circling approach (more than 30 degrees offset), you can however descend down below the MDA on that 40 degree offset if you keep the runway environment in sight and have the required charted criteria.
Originally Posted by RAT 5
By the way, Airbus don't allow setting the MDA in the ALT window.
Nothing stopping you having the circuit altitude set for a visual circuit.