Approach speeds

[FlyingForFun]

It's amazing what you don't even realise you don't know. I discovered, only recently (much to my embarassment), that PANS-OPS specifies a maximum speed to be used on a racetrack or reversal procedure for each approach category.

For example, for a Category A aircraft, the maximum speed to be used is 110kts.

I compared this to my company's standard procedures. We operate Cat A aircraft (BE76) with a threshold speed of 76kt. However, we use a much higher speed on the approach (100kt) in order to avoid ATC disruption with faster aircraft behind us, and reduce the effects of cross-winds - only slowing first to 85kt then 76kt when visual and on short final. This seems to be fairly standard procedure (from my own experience, at least) across the training industry and most of the light aviation industry as far as light twins are concerned.

So far, so good. But our speed at the start of the approach will typically be higher than the 110kt specified by PANS-OPS.

Our SOP is to fly to the IAF, and fly the hold, at 120kt. We leave the IAF at 120kt, then lower 10 degrees of flap which will slow us to 110kt. At the FAF we lower gear and 20 degrees of flap, which slows us to 100kt.

Is this allowed? I guess the 110kt maximum is there to ensure a maximum radius of turn, so if we have reached 110kt before making a turn, can we still follow a Cat A procedure?

And if the answer is No, are we allowed to fly a Cat B procedure, with Cat B minima, despite the fact that the type is a Cat A type (based on the stall speed/approach speed from the manual)? Are we then allowed to revert to Cat A once we have slowed the aircraft to below 110kt (assuming the procedures for Cat A and Cat B are the same up to this point, but Cat A maybe has a lower vis minimum)?

Any thoughts welcome!

FFF
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[airseb]

interesting question though I seem to believe that these definitions have to do mainly with:

the final categorie's approach speed defines the tax you pay on the approach and landing. typically the A321 should be CAT C for it's landing speed (142 kts) but is consideres B for the taxing

also the speeds are used to define approach construction protections. that's what is used to give you a racetrack return time that depends on your categorie. these times (if they're given in time and not in distance) usually depend on the categorie of the aircraft. same is true for an inversion procedure or a circling.

what you should do though depends on what procedure you're flying, i guess. if you're flying your racetrack at 180 kts it's good sense to consider the cat B times.

seb

[ft]

Check this thread (http://www.pprune.org/forums/showthread.php?p=3149807) out.
Basically and IIRC, and this I have no authority on so go to the source if it is critical, PANS-OPS defines a speed range for the various categories for various phases of flight. Your aircraft is certified for a given category, but if you for one reason or another cannot or will not maintain the speed range of that category for any given phase of flight, you must also upgrade your category accordingly and fly the procedures, minima etc for the speeds you are in fact using.
Rgds,
/Fred

[An Paddy Eile]

FlyingforFun,

The procedures you are flying will likely be designed for Cat A & B aircraft at least if not for A, B, C & D. In terms of procedure turns, if Cat B, C or D aircraft are allowed to use the procedure then the protected area will cover the highest speed that can be used. So you could in theory wizz around the procedure turn in your Duchess at 200 knots and still be OK.

As a further explanation - I previously flew for a turboprop operator. When operating into big airports with procedures designed to be used by any aircraft we could complete the initial approach at any speed we liked. We just need to be sure that we were at the appropriate speed for our category (B) for the final approach. But, when we flew into small regional airports, some of the procedures were authorised for use by A & B aircraft ONLY. This would usually be expicitly stated on the appraoch plate or you would simply realise that only Cat A and Cat B minima were published. We then had to ensure we flew the procedure turns at a max of 140 knots.

But if the entire procedure is designed for Cat A only, then you are correct. You can not fly the procedure turn at 120 knots. If only Cat A minima are published for the approach, then this is the case.

[An Paddy Eile]

Just wanted to add:

It is exactly the same case for holding. As far as I remember the PANS OPS holding speed for a Cat B Turboprop was something like 175 knots, but it sepcifically says "for holdings limited to Cat A & B only" or something like that. The important bit is the word "holdings" which means holding patterns. So you only need to fly the hold at that speed or less if it was designed for A & B only. Otherwise you could fly a regular published hold in your C150 at 220 knots and not break any rules (other than you AFM speed limits!) or bust any airspace or protected areas.

Of course it doesn't make sense to hold at 220 knots in an average turboprop but you could legally do it all the same.

[FlyingForFun]

Some good thoughts.

FT, thanks for the link, which doesn't directly answer my question by does raise some interesting points.

Eile, your reply (that the procedures are generally the same for Cat A and B) is what my colleagues said when I discussed it with them. However, they will normally have different RVR minima for the two categories. And there is one particular airport we go to where the approach is given for Cat A only. It's these specific cases that I'm interested in.

You said, regarding flying a Cat A/B approach, that:
We then had to ensure we flew the procedure turns at a max of 140 knots
Were you allowed to fly the procedure up to (but not including) the procedure turn at greater than 140kts? If that's the case, then it pretty much answers my question, since we will always be at 110kt before a procedure turn on any approach.

Thanks for the all the replies so far!

FFF
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[Oktas8]

It's not only turn radii that determine approach category, but also distance covered on time-based straight lines (that is, where outbound distance is timed rather than DME based). You are supposed to fly the entire approach at the correct speed to ensure that you don't get too far from the start point before the turn.

ICAO has tried hard to develop standards and recommended procedures that work everywhere in the world, from Canadian winters to Afghan summers. The rules might seem a little silly around benign terrain and well designed airfields in SE England.

What you suggest would probably work just fine in Britain, but how could you safely remember to apply this set of procedures in EGBH and that set of procedures in say Tibet? The men in white coats at ICAO seem to think it's best to have one set that work everywhere.

Cheers,
O8