Circling Minima

[flatron222]

For circling which minima to be used.

Example Rwy 27 Minima circle to land 1780ft

Rwy 07 Minima cicle to land 1850

I would make an app for rwy 27 but than break out and land on 07...

Pls advise what is the circling minima should be ued:eek:

[arba]

which approach plate you use? on that, your circle to land MDA is written.

[eckhard]

My understanding is that all minima are those which apply to the instrument approach being used (as already mentioned by Arba, above).

In your example, you are flying the instrument approach to RWY 27, so you would use the circling minima for RWY 27 (1780ft). This would be applied for the circling manoeuvre from RWY 27 to any other runway.

In my experience, circling minima are usually the same for all instrument approaches to all runways at any particular airport; after all, you are going to manoeuvre in a pre-defined area irrespective of your initial track. The terrain clearance in this area is what should determine the circling MDA.

Some airports will divide the circling area and publish different MDAs for the two sectors. This is normally done to avoid a prominent obstacle and thereby achieve lower minima.

The difference in the minima for the two runways in your example is puzzling. I would venture that it derives from the different threshold elevations. I would have thought that using the airfield elevation would be easier. This could be an error on the part of the approach designer. In practice, use the higher of the two minima and you should be OK. Do you have a chart that you could show us?

The important thing is to understand the dimensions of the circling area and the actual terrain clearance that the circling MDA gives you. This varies according to whether the approach was constructed using TERPS or PANS-OPS criteria. Also, remember that there is a maximum speed for circling, dependant on aircraft approach category (A,B,C,D).

The circle-to-land manoeuvre is one of the most challenging ways of completing an instrument approach and landing, especially in poor weather or at night. A good understanding of the parameters and a clear plan vis-a-vis use of autopilot modes, gear/flap settings and speed control is vital to avoid the many accidents that have befallen many of our colleagues.

Don't forget that the missed approach for a circle-to-land is the one relating to the instrument approach that you have flown. Have a plan in mind regarding tracks to follow in the event of losing visual reference during the manoeuvre. Generally, a turn towards the airport is a good first move.

Hope this helps and take care,

Eckhard

[BOAC]

As eckhard says - this is very confusing - the minima are normally the same for all approaches - can you tell us which airfield and which chart producer?

[bfisk]

This situation can be created if there are significant obstacles or terrain to one side of the airport (the far side), but that are outside the circling area.

Example: The airport is located near a coastline running north-south; the sea is to the west and to the east there is high terrain. The runway is oriented 09/27, ie perpendicular to the coast. There are straight-in instrument approaches to either runway, and both have circling minimas.

The approach to the 27 runway takes your over the high terrain, and when beyond it, lets you down on a glideslope; let's say to 200 feet. The missed approach takes you out over the sea and is as such not controlling. However there's a few buildings and towers to the north of the airport, so the circling minima is higher; let's say 700 feet.

The approach to 09 takes place over water. However to ensure missed approach capability, because the missed approach takes you toward the high terrain, the minima is much higher; let's say 1000 feet. Obviously the circling minima for this approach could not be 700 feet, as for the other one, because if you flew down to 700 feet to have a look-see, and there was nothing, you would be beyond the design criteria for the missed approach.

It can be solved a number of ways: leave it be, design another missed approach if possible, or publish lower minima based on higher missed approach climb gradients (not standard for PANS-OPS but is done in some places).

:ok:

[galaxy flyer]

To answer the OP, use the minimimsfor the instrument approach flown. In your case, you flew an approach to 27, circle to land 07, one would you the circling mins on the 27 approach.

GF