1/20/2011 Near Midair - AA B-777 & 2 C-17s

[SteveCostello]

Out of curiosity, what are the lateral separation rules for aircraft approaching parallel runways?

 

[TFaudree_ERAU]

Out of curiosity, what are the lateral separation rules for aircraft approaching parallel runways?

I don't know the answer to that, but I do know the reason for the reduced minima. Radar update rate, and area (like square miles) of controller responsibility. Also, the resolution of an enroute controller's scope is much much lower than that of a final approach controller's scope.

 

[SteveCostello]

I don't know the answer to that, but I do know the reason for the reduced minima. Radar update rate, and area (like square miles) of controller responsibility. Also, the resolution of an enroute controller's scope is much much lower than that of a final approach controller's scope.

Oh... I know. Not to mention the fact that the flight paths are not convergent. I just wanted to compare that separation mandate from the separation these guys had.

 

[Hacker15e]

what you guys do for normal ops is 100% unacceptable to airline ops.

Seriously? You believe there is 0% applicability? There's no airmanship or judgment aspects, or situational awareness, that are being built in all of that high performance maneuvering?

Horsepucky.

If that were the case, then no tactical background pilots would ever be hired at 121 operations.

 

[dasleben]

Seriously? You believe there is 0% applicability? There's no airmanship or judgment aspects, or situational awareness, that are being built in all of that high performance maneuvering?

Horsepucky.

If that were the case, then no tactical background pilots would ever be hired at 121 operations.

C'mon, you know that's not what he's saying.

 

[Hacker15e]

C'mon, you know that's not what he's saying.

I believe I know exactly what @jtrain is saying, but he's only partially correct.

I think John believes I want to blanket apply combat-zone and tactical flying risk management strategies to 121 airline operations, and that's utterly off the mark. I don't believe that in any way whatsoever -- but I do think there are ways that some of them apply very well.

I'm not arguing that the rules are the same or should be the same between the tactical military realm and the 121 airline ops realm. I'm perfectly aware that there are significantly different priorities which drive aeronautical decision making in the tactical military environment and in 121 airline ops. Things that are acceptable in one aren't in the other, obviously, for a multitude of reasons. I've all ready stated my complete comprehension of that on numerous occasions. To say that there is absolutely zero in common between the two in terms of ADM/risk management/judgment, though, is just ignorant. There are actually lots and lots of commonalities, and the decisionmaking skills are very easily tweaked and ported from one to the other.

I still find it an eye-roller that so many pilots see this incident as a "seconds from death" issue. I just don't see it that way. Certainly it was a big problem, and a cause for concern, though. My belief, as stated in earlier posts, is that the ("over") reaction to this situation is rooted in pilots who have a lot of time operating in the safe cocoon of IFR separation and have developed perceptions of threats based on that experience. I believe that the threat is over-rated in this situation. I still maintain that 2000' of separation -- lateral or vertical -- does not constitute a "near midair" as described in the thread title, regardless of if the FAA defines it that way or not. Yes, I understand airliners aren't that maneuverable. Yes, I understand that you can't bank up to 135 degrees and pull 6Gs to avoid a midair when you have 300 paying pax in the back that you're trying to safely get to Miami. This is a perception discussion, not a mechanics discussion. I'm talking about what pilots perceive as being dangerous compared to what may be "actually" dangerous.

Was it a bad situation? Certainly. Does it warrant a lot of discussion? Definitely. Are there lessons to be learned? Without a doubt.

Again, from my perspective it just wasn't as severe as people are treating it.

 

[seagull]

I think Hacker captured the points well, nice job!

 

[jtrain609]

C'mon, you know that's not what he's saying.

Doesn't matter what I'm saying. There's too much talking and not enough listening going on to have any meaningful discussion about this one. If I had been in either of those cockpits, I'd be cleaning my shorts out regardless of how close or not close somebody thinks it was.

 

[dasleben]

I still find it an eye-roller that so many pilots see this incident as a "seconds from death" issue.

Good post, but I don't recall ever posting that it was a "seconds from death" issue. You may have taken that ball and run with it. I've had near misses well within 2,000' separation, and it wasn't a life or death situation. My concern was that it was a mistake on ATC's part, and that 2,000' may have very well been 200', or 2', had the 777 not followed the TCAS RA.

I'm not sure where the 121 vs. Military debate started up; I fly with a lot of ex-military pilots who do fine in a 121 environment. I think that one is between you and Mr. Train.

 

[SteveCostello]

... I still find it an eye-roller that so many pilots see this incident as a "seconds from death" issue. ... I still maintain that 2000' of separation -- lateral or vertical -- does not constitute a "near midair" as described in the thread title, regardless of if the FAA defines it that way or not.

Sorry. I respect you, and enjoy reading your posts, and have learned from you, but... I have to call BS on this. You are telling me that two directly (not even off-parallel, but ~130º) converging flight paths of three LARGE aircraft, at the same altitude, each traveling in excess of 250 knots less than 2,000 feet away from each other is not a near midair? You're insane.

 

[SteveCostello]

Out of curiosity, I whipped up an image. Some assumptions had to be made, so I erred in the low side of things. Please... tell me if I am off base on this. Naturally, this image is not to scale, but the math is correct, based on the image that has already been provided in this thread.

Assumptions made:

1. Both aircraft are traveling at 250 knots.
2. Both aircraft are equidistant from the potential impact point.
3. The 2,000' lateral separation would be measured from the aircrafts' two closest points, in the case, that would appear to be the nosecone.

Given that information, the C-17 would be 1,013 feet from the point of impact, and the 777 would be 1,115' from the point of impact. Traveling at 250 knots each, the C-17 would have 2.39 seconds to react, and the 777 would have 2.63 seconds. If that's not a near midair, I'll aviation quit right now.

Please... feel free to double check the math, the angles, etc. I've erred on the side these guys only going 250 knots, and it has been mentioned in this thread that they were likely going much faster than that. Either way you slice it... these babies were close, and were traveling toward each other really fast. I'm not sure what I'm missing here.

 

[SteveCostello]

Huh... for some reason, the image I saved did not have the angles displayed. Sorry. Angle A, between the two aircraft, is measured at 140 degrees. B, at the C-17, is measured at 21, and C for the 777 is measured at 19. This is based directly off of the image posted earlier in the thread.

Also, the article is a little ambiguous. Did the aircraft come within 2,000' during evasive maneuvers? At the beginning of the evasive maneuver? If they came within that distance during the maneuver, then it would be interesting to know what their respective positions were just prior to any action.

 

[Hacker15e]

By my read, 2000' is the closest they approached. That is a very different situation than the one you depict in that graphic.

 

[FlyingScot]

I think at flight level while crossing the ocean you are out of the see and avoid phase of flight and are in the fat dumb and happy phase.

 

[dasleben]

I think at flight level while crossing the ocean you are out of the see and avoid phase of flight and are in the fat dumb and happy phase.

Well, I wouldn't put it in those words, but there are a lot of distractions occurring around that time. Passing through FL220, I know I'd probably be on the SATCOM talking to dispatch, reading off departure information. The other guy would more than likely be on autopilot, looking up the oceanic entry point estimate, and potentially setting up the FMS for cruise. There's a fair amount of heads-down time going on.

 

[PositionAndHold]

I know what most FOMs say, and what the FAA recommends. I'm not advocating to regularly just blow off RAs. Hell, I'm not even advocating to do it every once in a while. Probably not even 1 out of 1,000 times in the operating environment that most of you are talking about (I'm completely excluding my operating environment because it obviously does not apply in any way to commercial operations in the US NAS or even ICAO airspace).

What I am saying is that if pilots are merely a slave to what the TCAS container is saying -- both in terms of data displayed as well as commands issued -- and not using all the tools available to build their SA and then operating their aircraft appropriately, then that is what is crazy.

With respect to "exact science", all I can say is that I have about 6 years experience flying TCAS I and II-equipped aircraft (both slow and fast movers), and I have seen it be less than precise on numerous occasions. Mostly they were displayed errors in both azimuth and altitude, and calls for RAs based on predicted maneuvering out of the other aircraft that never happened or happened differently than predicted. Or, it was displays not showing aircraft that were squawking, or the opposite -- showing phantom traffic that did not exist. In the fighters, especially, we were the ones messing with the TCAS-equipped aircraft and causing them to get all hot and bothered; TCAS doesn't predict the speeds and climbing / maneuvering capability of a fighter, and because the system lags, we could be setting off RAs even when we weren't remotely any conflict for the other aircraft. More than once I have had aircraft climb or turn into me while following an RA -- a situation where I saw them the entire time, and they obviously did not see me.

As an aside, in fighter and combat operations, I give TCAS even less importance in my SA heirarchy for a number of reasons. Let's not forget that TCAS is trying to maintain some relatively large miss distances between aircraft as well as command relatively smooth and light G maneuvering to do it. In a potentially very crowded environment (for example, a 'stack' over a target where aircraft are at 500-foot altitude increments doing circles of various radii, speeds, and directions) and filled with non-squawing aircraft (like every #2 of a formation), not only does TCAS sometimes try and make me climb/descend into someone else's airspace to 'avoid' someone who is not going to hit me because of established altitude deconfliction, but it also doesn't see all of the idiotic wingmen out there who are moseying around at other-than-their-assigned-altitude and not even appearing on the TCAS display. In that situation, I go to STBY or TA, and only use the display for helping get my eyes on something I haven't been able to pick out of the sky yet visually. So, for the purposed of this discussion, I'm completely disregarding those types of experiences because we just don't see that in common carrier operations.

Again, look at the conflicting commands seen in this exact situation and look at the lines on the admittedly non-scientific map posted -- there's direct evidence that the system isn't perfect. Even if we flew in a perfect world where every aircraft was flying around with a TCAS II or better system on board (and obviously we know that is far, far from the truth), this would not be a perfect system. Bearing in mind that there are a whole crap-ton of aircraft operating in the National Airspace System that aren't so well equipped, then it's just not possible to christen the system as the Saviour. Is it good? Yep. Does it provide value? Absolutely -- I think it's a magnificent system and I really like flying aircraft that are so equipped. In no way, though, does it replace my duty as an aviator to clear my flightpath, nor does it replace my responsibility to build and maintain SA, and respond appropriately to possible conflicts. TCAS is a single piece of information in building that SA.

But, hey -- if the FAA's printed information on it says it's perfect and precise, then I guess it is, right?

I have roughly the same amount of experience with TCAS. All of it being TCAS II and most of that with change 7. While I fully agree it can give false targets and not refresh fast enough to spot traffic. When it comes to deconflicting two aircraft, it does a tremendous job. It pretty much saved our bacon comming out of OXR last week. Some one was sneaking out of the LA Class B as we were level at 5,000 doing 250kts. We were busy trying to find previously called traffic. All of sudden he flips on his tansponder, twelve o'clock, same alt, opposite direction, less than a mile. As we see him on TCAS, and start to look, it gives us the descend RA. At the same time, he pops up on Mugu's radar while we're in the middle of the RA. He came across the top of us, head on at about 500ft, never even knew we were there. That all happened in about 30 seconds. We were both heads up looking out the front for traffic and I really don't think we would have seen him. Small piper head on, not moving laterly, makes for a small target.

In fighters TCAS might just be another SA tool. In transport aircraft, It's much, much more than a simple SA tool. While nothing replaces a good heads up visual scan, I'll take TCAS every day of the week and twice on Sunday.

It works. It's saved numerous lives over the year. There's a reason why it's mandatory.

 

[Chief Captain]

Not sure about military separation standards, but here's how I gauge it.

If we get a TA, it's fairly uncommon, and enough to make you perk up and pay attention

If it gets to the RA stage, multiple levels of safety have failed, and TCAS had to step in to prevent an accident.


The only time I wouldn't consider an RA event as serious is if I 100% positively have the traffic in sight, and I'm manoeuvring accordingly. That wasn't the case in this incident.

 

[genot]

Out of curiosity, what are the lateral separation rules for aircraft approaching parallel runways?

Depends on distance between centerline and if visual approaches are in use. For visuals, they can be side by side with 2,500 feet between runway centerlines provided the intercept angle is 30 degrees or less. Those same runways in IMC are 1.5 miles in trail between aircraft going to different runways. Anything less than 2,500 is either same runway separation (in lieu of visual) which is typically 2.5 miles at most major airports, or 3 miles if no runway occupancy study has been completed. Of course if PRM approaches are in use, you can run simultaneous ILS's much, much closer than 2,000 feet.

 

[genot]

Not sure about military separation standards, but here's how I gauge it.

If we get a TA, it's fairly uncommon, and enough to make you perk up and pay attention

If it gets to the RA stage, multiple levels of safety have failed, and TCAS had to step in to prevent an accident.


The only time I wouldn't consider an RA event as serious is if I 100% positively have the traffic in sight, and I'm manoeuvring accordingly. That wasn't the case in this incident.

At least in my experience I disagree that if TCAS steps in it automatically prevented an incident. Or that every time an RA is received that automatically means multiple levels of safety have failed. Does it at times? Absolutely. 95% of the time I've seen an RA however , it was between two positively separated aircraft who were aware of what each other were doing with a timely and detailed traffic call. I'm sure receiving an RA isn't exactly a gentle experience and I can absolutely agree that receiving one when you don't see the traffic, even if the other traffic sees you is a rather serious matter. Having said that, the TCAS software isn't aware of the actual plan of action and can and does act on normal separation.

 

[derg]

I think of it like this:

3G's in a military jet, probably standard ops I guess. I don't know.

3G's in a transport category aircraft with 221 people behind the locked cockpit door, FOQA is going to start screaming and you're probably going to get a call from the chief pilot.

What's no big deal in one operation can be a HUUUUUUUUUUUUUGE deal in another so I have to look at it from the perspective of what I do.

I had a close call over S. America -- I'm not sure how close it was, but it was big enough so that if I didn't turn off the autopilot and manuever the aircraft immediately it would have been pretty loud I think. But there were a lot of phone calls being made after that one.

I got within a mile of a Navajo one day on arrival into CVG one night and the controller called our arrival gate to apologize.

In the civilian world, especially the airline world, we don't like to see other airplanes which we're not flying parallel with, or if we know are under positive control. When JFK vectors us too low over Long Island during the weekend, it's nerve-wracking because the weekend warriors are out and people bust airspace all the darned time. AND you gotta watch out for the "elevators" with the skydivers too.

Over the ocean, merging traffic, oh yes, that would certainly pique my interest for sure. Hell, we even have a procedure for crossing tracks when we're on a random route to be sure we're "seen" and are alert of the potential of other aircraft. The oceanic sectors can be the wild west at times and if you add a rookie or two (not saying the 777 or the C-17's were by any means), it can get downright dangerous if you're not careful.