Tenerif... AUSTIN!

[Evan]

3-7-5. PRECISION APPROACH CRITICAL AREA

I want to believe that, but realistically, how often is the localizer protected above CAT II? I'm guessing it is pretty much SOP at busy airports to allow departures on the runway when the arriving aircraft is inside the outer marker under CAT I conditions. With ceilings above a minimum 200' DH, that should provide a reasonable safe margin for ILS distortions.

Moreover, what does this exception mean:

1. LOCALIZER CRITICAL AREA

(a) Do not authorize vehicle or aircraft operations in or over the area when an arriving aircraft is inside the ILS OM or the fix used in lieu of the OM when the official weather observation is a ceiling of less than 800 feet or visibility less than 2 miles, except:


(1) A preceding arriving aircraft on the same or another runway that passes over or through the area while landing or exiting the runway.

(2) A preceding departing aircraft or missed approach on the same or another runway that passes through or over the area.

Which, if I understand that right would allow for the SW 737 to be in the protected area under CAT I.

Whereas:

(b) In addition to subparagraph a1(a), when the official weather observation indicates a ceiling of less than 200 feet or RVR 2,000 feet, do not authorize vehicles or aircraft operations in or over the area when an arriving aircraft is inside the middle marker, or in the absence of a middle marker,1/2 mile final.

Subpart (b) has no exceptions. That's CAT II or CAT III.

Also, the hold markings are using the Pattern "B" (ILS protected area) version for CAT II/CAT III but not CAT I:

[Gabriel]

Moreover, what does this exception mean:

That exception is for the localizer critical area, not for the glideslope critical area. The localizer critical reaches only so far down the runway, Southwest would not have intruded it until it was airborne.




The glideslope critical area, however, has no exceptions whatsoever.

Now, 2 new things I found out:
1- The glideslope critical area seems to be more case-by-case than a general geometry like the localizer critical area. You can "engineer" the relative positions of the glideslope antena, the runway and the taxiway to minimize the impact on operations. Example below.
2- In a previous comment (I think somewhere else, not in this forum) I said something that now I think is wrong. I said something like "In Austin's RWY 18L, there is an ILS protected area hold short line on the taxiway at the left of the runway, but not at the right, so I suppose that the normal hold short line in the taxiway at the right serves as ILS protected area too". (left and right as seen by a plane landing in 18L)
I now think that is wrong because: what I said in 1 (including the figure below), and I was looking at google maps again and the normal hold short lines on the taxiway at the right are not double lines as the ILS protected area lines (like the one at the left of the runway).
Now I think it is very possible that Southwest never intruded the glideslope protected area.

As of whether it illegally intruded the localizer protected area, I don't know. FedEx was in a 3 miles final when ATC cleared Southwest for take-off, so that would comply (req = inside MM or 1/2 mile final). But did he expect that Southwest would be clear of the localizer protected area by the time FedEx was 1/2 mile out? And do expectations matter or just the initial authorization? The rule is not clear to me.

In any event, this TOTALLY exonerates the FedEx crew for the crime of not going around when the ILS protected area was violated, because it wasn't or at least it would be hard for the crew to recognize if it was. Going around at once could have been a good judgment call nonetheless, but I won't criticize the judgement call of the crew that made the judgement call that saved everybody's lives out there.

Note in this example how everything is out of the glideslope critical area.

[Evan]

That exception is for the localizer critical area, not for the glideslope critical area. The localizer critical reaches only so far down the runway, Southwest would not have intruded it until it was airborne.

Yes, the glideslope protection was never an issue here. It's the localizer that matters on the threshold end. Airfields like this one keep the GS antenna on the opposite side of the runway anyway, so taxiing aircraft can't disturb it.

[Evan]

Now I think it is very possible that Southwest never intruded the glideslope protected area.

As of whether it illegally intruded the localizer protected area, I don't know. FedEx was in a 3 miles final when ATC cleared Southwest for take-off, so that would comply (req = inside MM or 1/2 mile final). But did he expect that Southwest would be clear of the localizer protected area by the time FedEx was 1/2 mile out? And do expectations matter or just the initial authorization? The rule is not clear to me.

The rule is that nothing can be in the protected area after that point without causing potentially catastrophic ILS distortions. It doesn't matter if it's been there all day or just arrived. That's the rule of reality. I'm not clear on the rule of the FAA, but outcomes obey the rule of reality.

In the NOT_US, London Heathrow requires the Cat II/III protected area clear when arrivals are within 1nm out. They require landing clearance by 2nm out or, if not possible, to expect late runway clearance which must come no later than 1nm out.

So, applying that to this incident... When tower instructed SW to taxi into takeoff position, was it reasonable to expect that SW would be airborne beyond the runway by the time FedEx passed 1nm out? And what about the unexpected?

Most to the point (and I think it's your point as well) runway clearance should never be issued until the runway is actually clear. Once clearance has been given, nothing should be allowed onto the runway. Expect late clearance, fine if the rules are adhered to. Controllers may try to squeeze that 737 in and if it doesn't get off before 1nm out, instruct the 767 to go-around. But it will go-around anyway at that point because late runway clearance never came. In any case, if the runway isn't actually clear at 1nm out, that's Cat III game over.

[Gabriel]

Ummmmmmmm.

I said any, you said active…

Pretty sure ground can CLEAR you to your takeoff runway and you have CLEARANCE to cross INACTIVE runways (and maybe active ones, too since ATC might know if there’s a gap in activity.)

However, if they say TAXI to your takeoff runway, you do not_have CLEARANCE to cross other runways.

….and yes, taxi instructions should also say HOLD SHORT if that is needed.

At flyover, planes routinely cross the “crosswind” runway which is usually inactive.

As part of a taxi clearance, they can clear you to cross any runway including any active runway, but they have to spell the specific runways you are cleared to cross one by one and you need to read them back one by one. If you are in A short of B and they clear you to continue on A left on C, and C is at the other side of an active runway, you cannot cross the hold-short line for said runway just with that clearance. And even if it is not an active runway, you can still not cross it unless you KNOW it is a not-active runway. "I didn't know the runway was active" is not an admissible defense. You cannot assume that since the controller gave you a clearance that happens to go across a runway and they didn't specifically clear you to cross said runway, then it must be a not-active runway.

This is something that changed from the times you and I flew. And for a good reason.

And by the way, in the most of the rest of the world, if they clear you to taxi A left of D right on F2 cross 18L and then left on B, they can only do that if nobody is cleared to take off or land in said runway, and they cannot clear anybody to take off or land in said runway until after you crossed it. So, unlike in the US, they normally don't give you a clearance to cross a runway as part of a long taxi (unless it is a boring day or a boring airport). They would instead say "hold short of 18L" and after they take off and land a few planes and you are approaching the runway they would clear you to cross it.

[Evan]

Flightradar24 has calculated the relative positions from the ADS-B data:

The Southwest flight SWA708 entered the runway at 12:39:37.996. At this time, the FedEx flight FDX1432 was 2.35 miles from the runway threshold. SWA708 began its departure roll at 12:40:15.075 when the FedEx aircraft was approximately .676 miles from the runway threshold.

Visibility was decreasing from .25 miles down to .125 miles. FedEx reached a minimum altitude of 75' AGL passing over the runway threshold. If they initiated go-around at 150' AGL, this illustrates the probability of collision when going around at Cat IIIa DH (below 100') or Cat IIIb DH (below 50').

FedEx ground speed over the runway was 138kts. Crossing the threshold, SW was 1000ft ahead at 74kts.

[3WE]

3BS is old and out of touch

Noted.

I will have to pull up Flyover ground on LiveATC. I don’t listen to ground a whole lot, but there’s usually a few runway crossings going on on any given day, I haven’t noticed Uber-strict attention to runway crossings. Often, the tower will say taxi to the gate with me and if it’s runway 30R, you’re likely crossing 12R-30L. The instruction indeed says “cross”, but it’s an obvious, fairly active runway. I also don’t recall the magic word cleared. For guys going out for takeoff on 12L or 29, there’s going to be a crossing, altough the route to 29 or in from 11 is a typically inactive runway. Should be a good test case,

[3WE]

Flightradar24 has calculated the relative positions from the ADS-B data: blah blah blah.

Who cares- even if it was 1000 feet, it was a bad failure of a lot of Swiss cheese….I sort of wish SWA AND Fed Ex had decided it was bad to continue…more regulation, procedures, oversight for ATC, and fire Boeing executives. (This is a friendly razz, “the system” performed mediocre, here.)

[Evan]

Who cares- even if it was 1000 feet, it was a bad failure of a lot of Swiss cheese….I sort of wish SWA AND Fed Ex had decided it was bad to continue…more regulation, procedures, oversight for ATC, and fire Boeing executives. (This is a friendly razz, “the system” performed mediocre, here.)

Who cares...? The system is insane if this is considered a reasonable procedure. Clear to land must mean the runway us all yours or we need to rewrite the dictionary. It's sort of like I have one sidestick and you have another and one of us has to say 'my airplane' and the other has to say 'your airplane' and stay off it. Except with runways. What we have here is a failure to communicate (read that with a flyover accent).

[3WE]

Who cares...? The system is insane if this is considered a reasonable procedure. Clear to land must mean the runway us all yours or we need to rewrite the dictionary.

Is this for a situation of 300 feet of vertical separation with no real lateral separation or a situation where you have 0.25 miles of lateral separation? You were quite focused on all the trees of exactly where and when each airplane was.

Does this also apply to cleared for takeoff, like in New York?

[Evan]

Is this for a situation of 300 feet of vertical separation with no real lateral separation or a situation where you have 0.25 miles of lateral separation? You were quite focused on all the trees of exactly where and when each airplane was.

Does this also apply to cleared for takeoff, like in New York?

Of course! Even in the big city. Anywhere. As Gabe said, expect late clearance is one thing (by 1nm, or go around) but issuing clearance and then offering that sacred runway to a common Southwest 737, well, it's quite frankly appalling!

It's the spoken words, "clear to land", that this is all about. It you want to shove in a departure, don't say those words until that departure departs.

Thems with credentials will tell of many atime when clearance came just afore the squeaking of tires on runway. And they go along with it!

Sometimes the obvious is so obvious (see: gun control) that you really have to wonder if any of this is even real.

[Gabriel]

Noted.

I will have to pull up Flyover ground on LiveATC. I don’t listen to ground a whole lot, but there’s usually a few runway crossings going on on any given day, I haven’t noticed Uber-strict attention to runway crossings. Often, the tower will say taxi to the gate with me and if it’s runway 30R, you’re likely crossing 12R-30L. The instruction indeed says “cross”, but it’s an obvious, fairly active runway. I also don’t recall the magic word cleared. For guys going out for takeoff on 12L or 29, there’s going to be a crossing, altough the route to 29 or in from 11 is a typically inactive runway. Should be a good test case,

You can receive a clearance without the word "cleared". "Turn left 270", "Climb and maintain 6000". "Cross 18L".
I think that the word "clear" was removed from ground operations except of "clear for take-off", precisely to avoid any possible confusion with a take off clearance.

"Cleared to the Papa beacon flight level nine zero, right turn out of zero four zero until intercepting the 325 radial from Las Palmas VOR" was once taken as a take-off clearance and it was a very, very bad day.

[3WE]

Sometimes the obvious is so obvious (see: gun control) that you really have to wonder if any of this is even real.

”Reality?”

It’s ok to like International cleared to land. But it’s sterile bubble mentality to not acknowledge an increase in last-second confusion, work and an increase in unnecessary go arounds that will place two airplanes in uncomfortably close proximity.

There is a trade off, but I know you cannot comprehend GRAYareas.

THEORETICALLY it might have prompted FedEx to go around sooner, but then again, it was the controller who screwed up…but maybe it’s better to not send someone around unnecessarily at JFK or LaGuardia…or you’ll have amazingly similar close passes from time to time.

Critical SA is important for both styles, and a hell of a solution for this would be adherence to IMC separation rules.

And, sure, obscure god knows we need more gun laws since we are already enforcing all of our existing laws and criminals will no doubt comply. Excuse me while I clutch my Bible…

[Evan]

”Reality?”

It’s ok to like International cleared to land. But it’s sterile bubble mentality to not acknowledge an increase in last-second confusion, work and an increase in unnecessary go arounds that will place two airplanes in uncomfortably close proximity.

There is a trade off, but I know you cannot comprehend GRAYareas.

I really have no idea what you're getting at there. Cleared to land must be BLACK and WHITE. There is no room for grey area there. You either have the runway to yourself or you aren't cleared to land.

I assume that there is a practical reason for not just giving each arrival a clean 2nm (or greater) clearance and holding everyone else safely behind the stop bars at that point. I assume that reason is a long line of planes on the taxiway and pressure from the airline operators who want to keep things moving on time. There is also the concern about burning too much taxi fuel. So, like RVSM, there needs to be a compromise on the margin of safety. With RVSM, the compromise involved more reliable automatic flight height-keeping equipment. Now you can cross corridors with 1000' vertical separation but only when operating on digital autopilot. That's written in black and white. With reduced separation clearance, for lack of a better term, there must also be black and white rules to keep things safe. And there are. The example I gave for Heathrow seems to be the minimal provision to keep things safe on lateral separation: clearance no later than 1nm out or go-around. No grey area to contend with.

So... Heathrow: SOP is cleared by 2nm out. There's a line up and they think they can get a departure in there so they tell the departure to taxi onto the runway for immediate departure and tell the arrival to expect late clearance. So far, safe enough. The arrival will now be prepared for go-around. In almost every case, the departure will get off before the arrival reaches 1nm out and the tower will then clear the arrival for landing. Everything goes smoothly. However, if something goes wrong and that departure is still on the runway when the arrival reaches 1nm out, either the tower instructs them to go-around or they go-around anyway because they've reached the decision distance, for lack of a better term, without getting clearance to land. Hopefully both. Again, inconvenience but no significant danger for the rare (not common) circumstance.

What we have here is a failure to communicate. The tower communicated a lie to the 767 (that the runway was and would remain clear), removing that layer of swiss cheese that a late clearance provides. The tower also communicated a sin to the 737 (to proceed onto a runway that had already been cleared for the 767). The 737 accepted that sinful act and the entire safety culture just imploded right there.

What should have happened here? See Heathrow. Tell the 767 to expect late clearance. Get the 737 on the runway. If it isn't off by the go-around time, tell the 767 to go-around, or at least never give them clearance to land. Or just keep the 737 behind the stop bar for another minute or two until the 767 lands.

Two essential things:
- Cleared to land means cleared runway. No grey anything.
- Clearance to land must never come beyond a point at which a go-around can be safely executed with another plane parked on the threshold (including a contingency factor for delay or error). .5nm is too close. And these stories I read from pilots getting late runway clearance moments before touchdown lead me to believe this is a more widespread problem than we think.

[Gabriel]

”Reality?”

It’s ok to like International cleared to land. But it’s sterile bubble mentality to not acknowledge an increase in last-second confusion, work and an increase in unnecessary go arounds that will place two airplanes in uncomfortably close proximity.

I would think that it is almost the opposite. Less confusion, less work, and yes, and unnecessary go-around may happen which is preferable to a necessary go-around not happening, and if you are concerned due to the close proximity of the go-around and the taking-off plane, I wonder what you think of the close proximity if said plane in the same situation landed instead.

There are always trade-offs and grey areas, but some greys are preferable to others. And this approach to "cleared to land" is on of the most clear-cut in my opinion.

THEORETICALLY it might have prompted FedEx to go around sooner, but then again, it was the controller who screwed up…but maybe it’s better to not send someone around unnecessarily at JFK or LaGuardia…or you’ll have amazingly similar close passes from time to time.

ATC screwed up, yes, but Swiss Cheese layers should cover each other's holes. Here it took a pilot brining a slice that was not part of the system to prevent a total air disaster. There was exactly zero layers of cheese in the system to cover for this kind of screw up.

And a go-around in JFK? What's with that? EVERY approach WILL end in a go around except that maybe you will not need to and will end up landing instead. That is (or should be) the mindset for pilots, ATC, and whoever designs the procedures and rules.

Critical SA is important

In another breaking news, the sky is blue.