Raise the mins?

[172driver]

You are in a category A aircraft shooting a straight in approach at 120 knots due to an ATC request, icing, or whatever reason. Do you raise the minimums to the next highest category if landing straight in?

I've always been taught to stick with the published mins for my a/c category unless circling. The AIM, IFH, and approach plates specifically state to raise them when circling but don't seem to cover the straight-in at a higher airspeed. Does this omission imply not raising them? I think so. So does our local DPE.

Unfortunately, AOPA and my local FSDO seem to disagree with this. They both say you must raise to the next highest category, whether straight-in or circling.

I know we're splitting hairs here, as the mins usually don't change by more than a 1/4 mile or so. Nevertheless, I would like to hear what you guys and gals have to say about this one. Anyone?

 

[tarp]

Do you use Jepps or have access to them?

There is a wonderful explanation in the Introduction Glossary under the term Aircraft Approach Category.

In it you will see that a Category A aircraft is predicated on a final approach speed of <91 kts. Jepp further defines this speed as Vat or the speed the airplane would be at in the landing configuration, 1.3 Vso just passing over the threshold of the runway. So, in your example would you be crossing the threshold at 120 or <91 kts?

To continue what Jepp says, the Category A aircraft has a speed "range" of 90-150 kts on Initial approach and a speed range of 70-100kts on the final approach segment (before reaching Vat). This may be the killer in your scenario. If you are still holding 120kts screaming down short final, you probably have to adjust up to the next category since the max speeds for the missed approach are predicated on 110kts on the final leg.

Your example was just a bit extreme since you took a Category A aircraft and flew it at speeds close to the top end of Category B. It always stuck in my mind that 110 (for A) and 140 (for B) are kind of "top end" numbers. Trying to do course reversals or to stay within parameters for holding on the approach are tough if you are screaming above these speeds. So 120 is excessive for Cat A and you should just go ahead and use Cat B #'s. Just like 150 is an excessive speed on the approach for a Cat B aircraft and therefore should be jumped to Cat C.

The one funny thing in all of this is when do you get told to hold 120kts to the Marker? Yeah about 4-8 miles from the marker. Are you now going to divert attention away from your planned approach or are you just going to plow on in and make it work. The only time you will be second guessed is if something bad happens.

 

[172driver]

Sounds reasonable but this is an ICAO table and there is a separate definition in the Jepps for USA TERPS which is much less clear.

 

[avbug]

An aircraft fits into only one approach category. However, any time maneuvering must be conducted above the upper limit of the approach category for your aircraft, you should use the next higher category minimums...the minimums applicable to the speed being flown.

See AIM Para 5-4-7 (b):

"...An aircraft shall fit into only one category. If it is necessary to maneuver at speeds in excess of the upper limit of a speed range for a category, the minimums for the next higher category should be used."

Lest one confuse this with the traditional similiar requirement for circling, the paragraph above is specifically iaddressed separately from circling.

If you're maneuvering at a speed in excess of the category for your aircraft, use the speed applicable to the speed you're using. This applies regardless of weather you are circling, or not.

 

[172driver]

So, maneuvering is not the same as circling? What, then, is maneuvering? Stabilized ILS straight in? Non-aligned final approach course? Side step?

I sure wouldn't define a straight in landing from an approach as maneuvering the aircraft though I suppose one could make the argument that the entire flight is considered maneuvering. I always assumed maneuvering from an approach meant circling to land.

 

[bozz66]

I agree that it just doesn't apply to circling minimums. I'm looking at an approach plate for Del Rio, Texas (DRT). Even the straight-in minimums for the NDB Rwy 13 are divided up into different approach categories. The visibility is ¾ for category A and B, 1¼ for cat C and 1½ for cat D. It is clearly raised whether circling or not.

 

[avbug]

172 driver,

Fortunately, it doesn't matter how you might define something. You may legally under Part 91 use the minimums appropriate to your aircraft category, which does not change. However, the AIM, TERPS, etc, is clear on the matter. If you are maneuvering (read, flying) at a speed near the upper limit of the particular category, you should use the next higher category.

Note the language used. Not when flying at a speed above your category, but even when operating near the upper limit of the category, you should use the minimums for the next higher category.

Are you required to? No. Should you? Yes.

This is specified as being critical when flying a circling approach because circling obstacle criteria, and associated minimae, are predicated on a radius from each runway end based on speed. If you are near or in excess of the upper limit of your category speed, you must use the next higher minimae in order to meet obstacle clearance requirements.

Regardless of circling, you should use the next higher minimums when above the category limits for your airplane, or operating near the upper category speed limit.

 

[TXCAP4228]

Missed appraoch

172 Driver, if you are still traveling at 120 knots by the time you get down to DH for an ILS that assumes 60 knots, your protected area is cut in half if you have to execute the missed approach.

Straight in or not, while climbing and turning to execute the missed, that 50ft/100ft/whatever difference (in MDA or DH) was planned in the terps to be enough to give you a suffcient area to execute the missed safely.

It doesn't have to have anything to do with circling, though that is one consideration.

 

[Checks]

"my local FSDO seem to disagree with this".

Doesnt surprise me.

If you are flying a CAT A aircraft you always use the CAT A mins for straight in. If you circle then use the appropiate category for the speed you are indicating.

 

[avbug]

Not so. You should use minimums appropriate to your speed, regardless of weather circling or flying straight in.

Again, note that we are directed to the next higher category, even when operating close to the upper limit of any given category. Even though we may not actually be flying fast enough to qualify for the next higher category, we are to use those minimums. Asked and answered: see previous.