Aircraft Categories

[IP076]

Could you provide the reference that says you are "Required" to use the higher minimums for a circling approach?

Also, you're looking for the margin above Vso. I don't know about all of you, but, on a circling approach, I'm not usually in the full landing configuration. (Usually only partial flaps) This only makes that margin smaller.

The other place a lot of people get mixed up with circling approachs is the Distance a pilot has to maintain from the runway complex throughout the manuever. Yes, you must stay within the prescribed radius, but you must also stay within the prescribed visibility requirements on the approach procedure. You have to keep the runway in sight, correct?

You can be 1.2 nm from the runway and not run into anything, but if the vis requirements are 1 sm (.87 nm) and the weather is at mins, you have to keep it in tight to keep sight of the runway.

 

[ksu_aviator]

AIM
5-4-7. Instrument Approach Procedures
a. Minimums are specified for various aircraft approach categories based upon a value 1.3 times the stalling speed of the aircraft in the landing configuration at maximum certified gross landing weight. In 14 CFR Section 97.3(b) categories are listed as follows: ...

...b. Aircraft approach categories are also discussed in the U.S. Terminal Procedures (commonly called approach plates), which states, among other things, that "An aircraft shall fit in 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." If it is necessary, while circling-to-land, to maneuver at speeds in excess of the upper limit of the speed range for each category, due to the possibility of extending the circling maneuver beyond the area for which obstruction clearance is provided, the circling minimum for the next higher approach category should be used. For example, an aircraft which falls in Category C, but is circling to land at a speed of 141 knots or higher should use the approach category "D" minimum when circling to land.

Simply put, 1.3 Vso determines your category unless you are using a higher airspeed and then that becomes your new category.

 

[IP076]

Again, that is correct. Its just that you are not "required" by law to do that. Now, does it make sense? Yes. Is it law? No.

Note that paragraph in the aim also says "should".

Legally, all you have to do is use the category that corresponds with 1.3 Vso.

Now, if you were circling at 130 in a 172 and used Cat A mins and ran into a mountain, I'm sure 91.13 would probably come up.

 

[Timebuilder]

Thanks for posting that AIM reference. When I made my post above, I was away from my reference CD.

 

[ksu_aviator]

here is the internet reference to the aim



IP, if you want to argue technicallities, there are no laws that require you to do anything in aviation. Only regulations.

You are right that any thing you are told to do in the AIM is covered under 91.13 in that going against the FAA's advice is considered Careless and Reckless opeartion.

Lets look at this.

Vref is controlling. If operating conditions require a higher Vref, your category does change (refer to (97.3). In absence of Vref, Vso x 1.3 is then controlling and the same applies.

If you fly at a higher airspeed then 135 and 121 ops spec always refer to the highest speed used. Now maybe part 91 you can get away with it, but I don't think I'd try it. I can't find the specific reg right now, but I'm sure it exists. Either way, 91.13 will always bite you if the FAA wants to get you.

 

[Deftone45075]

In the case of a turbo-prop, the affects of losing an engine on the approach would be slightly higher than a jet, however with the torques already reduced, it will not be much of a factor. Vref provides plenty of a margin above Vmca, including maneuvering.