Approach category speeds

[azaviator08]

I know the speeds for the approach category are based on Vref, or 1.3 x Vso. Does Vref refer to the speed at which you come down on the approach? This is what I always thought. But, for the airplane that I fly we come down at 120 for the approach and the 1.3 x Vso = 88 so I am a little confused. It says if a Vref is published if not use 1.3 Vso. I cannot find a Vref in the POH, 120 is just a procedure. I usually use category B, should I be using category A??

 

[MikeD]

I know the speeds for the approach category are based on Vref, or 1.3 x Vso. Does Vref refer to the speed at which you come down on the approach? This is what I always thought. But, for the airplane that I fly we come down at 120 for the approach and the 1.3 x Vso = 88 so I am a little confused. It says if a Vref is published if not use 1.3 Vso. I cannot find a Vref in the POH, 120 is just a procedure. I usually use category B, should I be using category A??

You can use the higher category all you like. You'll just have some higher MDAs, but you'll gain maneuvering space. Use Cat E if you like. Just can't use a lower category unless meeting certain speed criteria for straight-in and missed.

 

[subpilot]

You use the category that is appropriate for your aircraft's Vref or 1.3 x Vso, or your actual approach speed... whichever is higher.

The way I think of Vref speed is that it is your reference, or baseline, speed for your approach. Do we fly Vref all the way down final? No, and actually the goal at my company is to be at Vref when crossing over the threshold. During the Approach we have a different speed known as Vtgt or approach speed and it is a higher speed that accounts for practicality (ATC flow) plus a safety margin for wind. We calculate Vtgt based on winds but the speed adjustment is referenced from the Vref speed.

 

[Hacker15e]

Does Vref refer to the speed at which you come down on the approach?

They're teaching at FlightSafety that Vref refers to the speed at which you cross 50' over the threshold. Your approach speed will be something higher than that.

Doesn't make sense to me, as all the jets I've flown compute a final approach speed and a touchdown speed.

 

[A150K]

I know the speeds for the approach category are based on Vref, or 1.3 x Vso. Does Vref refer to the speed at which you come down on the approach? This is what I always thought. But, for the airplane that I fly we come down at 120 for the approach and the 1.3 x Vso = 88 so I am a little confused. It says if a Vref is published if not use 1.3 Vso. I cannot find a Vref in the POH, 120 is just a procedure. I usually use category B, should I be using category A??

I would use Cat B...I always use CAT B in the 172 since I'm usually fly the approach a knot or two faster than 91 knots. If getting in at CAT B MDA is a concern and you want to use CAT A, then you'll have to slow down to <91 KIAS-if you're palne is incapable of approaching at those speeds, then you just can't do it.

 

[Crockrocket94]

If I compute a VREF speed of 100 and a VAPP speed of 105, then my category is based off of the VREF of 100. Which I believe is Cat B.

 

[Autothrust Blue]

I would use Cat B...I always use CAT B in the 172 since I'm usually fly the approach a knot or two faster than 91 knots. If getting in at CAT B MDA is a concern and you want to use CAT A, then you'll have to slow down to <91 KIAS-if you're palne is incapable of approaching at those speeds, then you just can't do it.

Probably prudent. The way we do things in the 172 is almost always a 90 knot final, unless we're really trying to get in.

Obligatory rant about TERPS. Category A for circling keeps you very close into the field, too — there's not a lot of wiggle room for obstacle clearance under TERPS criteria. PANS OPS affords more generous obstacle clearance while circling. This has bitten some air carrier pilots before who assumed PANS OPS-style clearances.

More reading: PANS OPS versus TERPS. TERPS circling criteria are significantly different from that of the rest of the world - mostly to permit the publication of approaches at smaller airports with nastier terrain in the vicinity. (There's no politics in my aviation!)

 

[MikeD]

Obligatory rant about TERPS. Category A for circling keeps you very close into the field, too — there's not a lot of wiggle room for obstacle clearance under TERPS criteria. PANS OPS affords more generous obstacle clearance while circling. This has bitten some air carrier pilots before who assumed PANS OPS-style clearances.

Thats why even in a 172, you can fly Cat D or even E if you like. You fly your same approach speed, just accept a higher MDA. And you get larger circling maneuvering room, if you so desire.

 

[Autothrust Blue]

Thats why even in a 172, you can fly Cat D or even E if you like. You fly your same approach speed, just accept a higher MDA. And you get larger circling maneuvering room, if you so desire.

The Company's chief pilot would be very pissed if I flew the airplane at 165 knots, but yes.

 

[MikeD]

The Company's chief pilot would be very pissed if I flew the airplane at 165 knots, but yes.

You missed what I said . Fly it at 90 knots or whatever your approach speed is, but take advantage of the extra circling distance available, which usually doesn't come at that much of a price in heightened MDA.....terrain/obstacle dependant, obviously.

 

[Autothrust Blue]

You missed what I said . Fly it at 90 knots or whatever your approach speed is, but take advantage of the extra circling distance available, which usually doesn't come at that much of a price in heightened MDA.....terrain/obstacle dependant, obviously.

*ding* Re-read, realization, nod.

 

[MikeD]

*ding* Re-read, realization, nod.

Haha, no worries. I just say that because flying the higher category's MDA and taking advantage of it's respective circling distance provided is perfectly legal. Again, depending on the obstacles and terrain around, generally the differences in MDA isn't that much, and sometimes if it is, then you'll see notes like "Cat E circling N/A" or something to that effect. Of course, if WX is right at mins for circling, then doing this may not be an option and you might have to use your normal approach category numbers.

In the 117, circling speed was generally around 190ish, up to 210 Ive seen when heavy. That 4.5 NM of TERPs airspace got eaten up rapidly.

 

[LOC-D]

Doesn't the circling protected area for the different categories go out the window the moment you descend below MDA ? When you start the circling maneuver, it's pretty much see and avoid right ? So even if you do fly outside the protected area, as long as you see and avoid any obstacles, you should be fine.

 

[fish314]

Doesn't the circling protected area for the different categories go out the window the moment you descend below MDA ? When you start the circling maneuver, it's pretty much see and avoid right ? So even if you do fly outside the protected area, as long as you see and avoid any obstacles, you should be fine.

I've always learned to do the circling maneuver AT the circling MDA (or above, wx permitting), and to only descend below the circling MDA once aligning with the landing runway and on a normal glideslope to land. So when I'm tooling over the hangars or the sides of the airfield (or McDonalds' or whatever), I'm still at the circling MDA and protected. As I'm bringing it around to the clear zone for the landing runway, then I'm getting below that.

 

[denver]

Haha, no worries. I just say that because flying the higher category's MDA and taking advantage of it's respective circling distance provided is perfectly legal. Again, depending on the obstacles and terrain around, generally the differences in MDA isn't that much, and sometimes if it is, then you'll see notes like "Cat E circling N/A" or something to that effect. Of course, if WX is right at mins for circling, then doing this may not be an option and you might have to use your normal approach category numbers.

In the 117, circling speed was generally around 190ish, up to 210 Ive seen when heavy. That 4.5 NM of TERPs airspace got eaten up rapidly.

This is a great idea on a night circle in a faster aircraft. I circle at 110 but using Cat C allows for more room when it is black and the VASI is broke. There is almost never a difference in MDA untill Cat D and only slightly higher visibility at Cat C so you can still see the airport at the circle limit area as per Cat. I try to never have to circle at night in bad weather.

 

[Blackhawk]

They're teaching at FlightSafety that Vref refers to the speed at which you cross 50' over the threshold. Your approach speed will be something higher than that.

Doesn't make sense to me, as all the jets I've flown compute a final approach speed and a touchdown speed.

That really does not make sense. If you are circling you do so not at your 50' speed but at your approach speed- so you should be using those approach speed minimums.

 

[Hacker15e]

That really does not make sense. If you are circling you do so not at your 50' speed but at your approach speed- so you should be using those approach speed minimums.

They weren't teaching to circle at Vref...I was just stating how they defined Vref. They advocated circling at something in the neighborhood of Vref+20