Descent below MVA

[ATC124]

Recently, an approach controller at my facility was told they were wrong by to descend an aircraft below the MVA although the aircraft would clearly never go below the MVA without reaching the next MVA sector (which was lower, obviously.) The controller argued the use of anticipated separation, familiarity with aircraft characteristics/rate of descent, and the use of “best judgment”(as defined in 1-1-1).

Thoughts?

 

[DankVectorz]

A lot of trainers would write someone up for that

Bad ones

Yes they would and I’m one of them. My trainee’s job is to prove to me that he or she recognizes the conflict and positively separates them. They can start doing whatever they please on their own ticket once they certify, but I’ll need verification that they aren’t just “lucking” their way into not getting steak-sauces

Like this

 

[Move78]

If you have radar monitoring then they either bust the MVA or they don’t. That’s like saying you can’t issue a descent to an altitude occupied by another a/c until they physically cross out. Even if they’re 20,000 feet vertically separated. What slow ass facility is this argument happening at?

 

[Deuce]

You realize every plane is a certain number of miles away from a higher mva right?

 

[Deuce]

Our bad. I guess we all forgot 10s, 11s, and 12s shall not discuss interpretations or separation rules. Thanks for setting us straight.

Relax Mr cool guy steak sauce, you just said you'd a1 someone for climbing aircraft 1 who is directly underneath aircraft 2 by 4 thousand feet passing tail to tail, if that's true you're a fool and you legitimately do need to be set straight

People are taking such hardline stances here I mean what are we talking about? Is the guy 2 miles from the MVA boundary and 10k above the MVA? Obviously it's fine to descend him. Is he 100 miles from the MVA boundary 200 feet above the MVA? Obviously this is not okay. Many trainees have bad judgement and some trainers have a lower tolerance, but certainly there are some cases where it's totally safe to issue the descent prior to crossing the MVA boundary. If you're telling me that it's never okay to issue the descent prior to crossing the MVA boundary even if the guy is 1 mile away and 100 thousand feet above it, totally ridiculous

 

[SunnyATC]

I’m going to think of this thread every time I see a center flow control program for congestion.

 

[DADDYSbabyBIRD]

Idk, if they lose radio comms they're going right into that 8000 MVA at 7000. You cool betting everyone in the plane's life on that?

Just saying, either they're both "positive control" or niether one is

"If they lose comms" can be applied everywhere in a way that can be a lack of positive control.

 

[PooseMaGoose]

It is as simple as this.... If the aircraft physically proceeds below the MVA in which it is currently operating, it is a terrain loss (excluding 5-6-3 operations). "Anticipating separation" is a term only applicable to the issuance of takeoff clearances and landing clearances in Chapter 3. It is not a wise strategy to issue clearances below an MVA assuming the aircraft will have entered a lower MVA in time.. but that doesn't make it a loss.

If anybody argues to the contrary, then they must also admit that they bust sep. every single time they altitude swap two converging aircraft with ample lateral separation. Every loss needs an associated rule/paragraph in the .65 to be validated as a loss at the service area level... and there is no paragraph in the 65 that correlates to this no matter how much somebody disagrees with the operation.

 

[Move78]

Bad ones

Like this

Tried to like this more than once

 

[Termine]

What is "anticipated separation" in this context? For example, in the airport environment "anticipated separation" specifically means applying either 3-9-5 or 3-10-6.

5-6-1c says you can vector "at or above the MVA" which means that as long as the aircraft is always at or above the current MVA then vectoring is legal regardless of their eventual/assigned altitude. But are you allowed to assign that lower altitude in the first place? The main place where minimum altitudes are discussed is 4-5-6. You must assign an altitude that is at least the MEA, except that in certain circumstances you can go lower. One exception is 4-5-6a2(a) which says that when radar procedures are used you are allowed to assign altitudes "at or above the MVA along the route of flight." I guess it's up to personal/professional judgement what "along the route of flight" means.

In the final analysis I think this is legal provided the aircraft was continuously at-or-above the MVA for the sector they were in, regardless of assigned altitude. It would be way too inefficient otherwise. But as 32 said, it's not positive control. Then again, when you're anticipating runway separation that isn't necessarily positive control either.

Two addendums: to head off any argument that 4-5-6 doesn't apply because the aircraft is on a random route and there isn't any MEA in the first place, I will ask, then what other rule says you need to adhere to the MVA? I don't believe there is another rule, except 5-6-1c, and for the sake of argument let's assume the aircraft is cleared direct to a fix rather than on a vector. So 4-5-6 is what we've got, unless you want to argue that you can clear them straight to the ground and I don't think anyone is arguing that. And the other radar rule you can apply is 5-5-9b which says that if the MVA sector is to protect for a specific and displayed obstacle then you can drop the aircraft to the surrounding MVA once they're past the obstacle itself, but again for the sake of argument we'll assume that doesn't apply to your situation.

 

[Phanatical]

Looks like we can’t assign 10,000 to anyone going towards the Rockies anymore

 

[DADDYSbabyBIRD]

Similar one at mine but an a/c was over a 7000 ft MVA at 9000 and issued 7000. Problem is that on their heading 30 miles away was an 8000 ft MVA so yeah not positive sep.

30 miles away? Are they going to be turned before it? If yes, then it's perfectly fine! If we used this logic with everything we couldn't do our jobs.

 

[Rico]

I always try to be decent both above and below the MVA.

Radar controllers get to anticipate separation. This is the way.

 

[slater]

Go 4 it. Anticipate that shit. Just gotta watch them more tho.SWA nope. AAL 737, all day long.

 

[Move78]

They’re also always a certain number miles away from a head on. Buncha bored dipshits in QC.

 

[Deuce]

Y'all need traffic

 

[Dolan]

It is not a wise strategy to issue clearances below an MVA assuming the aircraft will have entered a lower MVA in time.

But this is wrong. We assume this kind of thing all the time. Swapping altitude with two planes pointed at one another 100 miles apart is an example. Turning a base toward a higher MVA without anything assuring the aircraft won't accelerate to 1000 miles an hour straight across final into terrain is another.

Airplanes are bound by the laws of physics and basing how you work around this inescapable fact is never an unwise way to work.

 

[DADDYSbabyBIRD]

This conversation reminds me of a trainer I once had that wrote me a box 1 for climbing an aircraft that was 4k below an crossing aircraft as the targets merged. Told me I has no positive separation... like the aircraft was going to magically climb multiple thousands of feet in the 1 second before we had divergence.

 

[jdatc]

Relax Mr cool guy steak sauce, you just said you'd a1 someone for climbing aircraft 1 who is directly underneath aircraft 2 by 4 thousand feet passing tail to tail, if that's true you're a fool and you legitimately do need to be set straight

This sounds like a center math problem.

But let’s use 3000’ and pretend they are right for direction.

Aircraft A has a ground speed of 420knots leaving Denver headed to JFK flying at FL330. Aircraft B has an airspeed of 360knots and has left JFK flying to Denver at an altitude of FL300. As aircraft A passes over aircraft B, you grant aircraft B’s request to climb to FL340.

At what climb rate would it set off the snitch, and they have less than 5 miles assuming an instantaneous climb at the very moment they passed each other.

13 mile a minute closure rate, means that they would be 5 miles apart (and thus separated) in ~23.07seconds. To lose separation would require the climbing aircraft to reach FL321 in 23 seconds per se.

So if they suddenly managed a 5500 foot per minute climb rate, you’d totally have a deal… maybe.

Now imagine if we add 3 seconds for us to transmit it to them, and 3 for them to read it back, executing it immediately upon completion of the read back. ~2100 feet in 17 seconds. Isn’t that a greater than 7500fpm climb?

i like maths!

 

[Dolan]

I never said I would A1 somebody for that. I said i would “write them up” because they didn’t show me that they saw it.

That's cool. I'd write them up for not doing it because it's completely safe and there's other things that need to be done.

It's almost like there's almost as many opinions on this stuff as there are controllers...

 

[32andBelow]

This sounds like a center math problem.

But let’s use 3000’ and pretend they are right for direction.

Aircraft A has a ground speed of 420knots leaving Denver headed to JFK flying at FL330. Aircraft B has an airspeed of 360knots and has left JFK flying to Denver at an altitude of FL300. As aircraft A passes over aircraft B, you grant aircraft B’s request to climb to FL340.

At what climb rate would it set off the snitch, and they have less than 5 miles assuming an instantaneous climb at the very moment they passed each other.

13 mile a minute closure rate, means that they would be 5 miles apart (and thus separated) in ~23.07seconds. To lose separation would require the climbing aircraft to reach FL321 in 23 seconds per se.

So if they suddenly managed a 5500 foot per minute climb rate, you’d totally have a deal… maybe.

Now imagine if we add 3 seconds for us to transmit it to them, and 3 for them to read it back, executing it immediately upon completion of the read back. ~2100 feet in 17 seconds. Isn’t that a greater than 7500fpm climb?

i like maths!

If the trainee said all that they’d have more leg to stand on. They usually don’t even understand what they are doing they are just emulating something they saw someone else do.