TACA aircraft crashed in Honduras
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RWA,
Of course I'm 'confused,' Lemurian.
But please educate me as to how (at the critical flaring stage) I could make certain sure that I had only applied a maximum bank angle of 5 degrees? Especially in an A320, that provides no 'feedback' on the sidestick? And PLEASE don't say 'by looking at the indicator on the panel'..........
So, in fact the *feedback* you'd be looking for is the position you'd want your aircraft to be at compared to where it is now. Correct ?
In all these cases, you'd just move your controls, be they yoke, stick or sidestick in order to achieve the desired result and you do not need to be a genius to fly a 'Bus. And forget all the shat about roll rates and so on...just pilot the damn thing and keep things simple.
Try and find a 737 landing vid from the cockpit and put the volume on full : you'd hear the click-clicks of the yoke that has a rather large neutral point (and CWS engagement, too, if IIRC). Would you still base your attitude estimation on those very poor references ?
As for the 5° limitation, they are quite all-encompassing of every airliner I have flown, the one where it was the most important was the 744 and it has to do with the geometry of the airplanes. Don't look for extraterrrestrial gremlins here.
my priority when landing was ALWAYS airspeed. Especially when gliding. In my experience (right or wrong) the wrong airspeed (either way) is more 'life-threatening' than attitude will ever be.
What really annoys me is people who have a bias, for or against and as a corollary, an agenda.
Prejudice is no argument .
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In each exchange re: AB & B, I've noticed a lean. It is generally subtle, though not always, and involves, I think a slightly different "approach" to flying. Bus adherents seem to be planted in a circle that tends toward automated, equipment dependent aviating. Boeing pilots, Stick and Rudder. The tipoff in the Bus argument is that peeping at the panel on very short final is preferable to peeking at the wingtip, or Horizon. One is left with the impression that Bus pilots think the trend is better when it favors CATIII autoland, Boeing pilots, see and react. There is no doubt in my mind that Piloting each type requires a different style.
Airfoil
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Funny, 'cos my experience of the posters on here is that there are automation fans and stick-and-rudder folk flying both manufacturer's aircraft. It's true that some pilots prefer the less cluttered AB flight deck arrangement and choose to fly AB as a result and others who prefer the denser, more hands on B design, but to say that the former are automation junkies (and indirectly knocking their stick and rudder skills as a result), or that the latter are more hands-on stick-and-rudder guys (and possibly implying an old-fashioned mindset in the process) is a gross overgeneralisation and a disservice to pilots of both.
Case in point, one of the most stalwart of the old guard on here (to the extent that he sometimes rubs people the wrong way) was flying the most technologically advanced aircraft of his generation and still has a great affection for it to this day. I bet he'd have something to say if you reckoned he was an automation junkie.
Case in point, one of the most stalwart of the old guard on here (to the extent that he sometimes rubs people the wrong way) was flying the most technologically advanced aircraft of his generation and still has a great affection for it to this day. I bet he'd have something to say if you reckoned he was an automation junkie.
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Face it, flying a jet has very little to do with visual cub piloting...
Part of being a jet pilot, I would guess and actually, the PFD is always in our line of vision and scanning it is an acquired technique...A second nature
Part of being a jet pilot, I would guess and actually, the PFD is always in our line of vision and scanning it is an acquired technique...A second nature
Are you flying single pilot Lemurian ?
Because the guy on your side is a Monitoring Pilot, his job is to monitor you and as part of your Standard Operation Procedures he should call you if your BANK or PITCH are approaching the limits.
During flare, I'm afraid, it is not time to look anywhere else … than outside !
Is there really a need to add anything to here ... or to the following:
Originally Posted by RWA
But in the sort of aircraft I was used to, to bank slightly into wind, I'd have applied pressure to the yoke (mere 'stick' sometimes) and also a touch of opposite rudder until my eyes - and the seat of my pants - told me that I'd managed to eliminate all or most of any drift
Lemurian, would you recognize these words ?
In order to assess the rate of descent in the flare, and the aircraft position relative to the ground, look well ahead of the aircraft
During the flare, the pilot should not concentrate on the airspeed, but only on the attitude with external cues
Specific PM call outs have been reinforced for excessive pitch attitude at landing
During the flare, the pilot should not concentrate on the airspeed, but only on the attitude with external cues
Specific PM call outs have been reinforced for excessive pitch attitude at landing
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But CONF, the monitoring pilot should be able to tell you that either via external cue or the instrument panel without needing to feel the stick or yoke. And indeed, with your second paragraph, the Airbus manual is corroborating Lemurian's point, regarding airspeed at any rate.
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Airfoilmod,
Things would be wonderfully simpler if they were that way.
Unfortunately, they are not and you still see the stick-and-rudder pilot on a 'Bus -and with a very accurate flying at that. and you can also see the *operator* (vs handler) in other types.
That sort of vocabulary was in effect long before the 320 first flight.
What is at stake here is plain biased thinking, as if to be a pilot one needed to keep the flight controls the pioneers used on their Ford Trimotor....
It's easy to see that it is just a load of buffalo crap : when B introduces new features, you wouldn't hear a pip (best example is the anti tail strike twitching on the 777, have you heard anyone on this forum protesting that it took his flying skills away ?)
As for looking at the wing tips, you're quite welcome to try that technique on a swept-wing jet...and the top of instrument panels are not reliable for giving you an horizontal reference...and when you do not have a horizon, like in a mountanous area, or in fog or against a misty sunrise/sunset, what will be your reference for wings level ?
That's why a long time ago I was instructed to watch horizon, airspeed and ball-and-needle during the flare (that was on a DC-4, mind you...) and I've kept that technique through all my later airplanes, of which the 'Bus is only the latest in a long line and it is no different.
But it is in the minds of a lot of haters, so they yell words like *roll rate* like a magical spell...Had they just stopped to think of it, the amount of lateral yoke you'd input is just that :how fast the airplane is going to roll, then, because physics take over,a turn is initiated...the beauty of it is that you won't be normally using your rudder...
Now I ask you, where is the difference ?
Unfortunately, they are not and you still see the stick-and-rudder pilot on a 'Bus -and with a very accurate flying at that. and you can also see the *operator* (vs handler) in other types.
That sort of vocabulary was in effect long before the 320 first flight.
What is at stake here is plain biased thinking, as if to be a pilot one needed to keep the flight controls the pioneers used on their Ford Trimotor....
It's easy to see that it is just a load of buffalo crap : when B introduces new features, you wouldn't hear a pip (best example is the anti tail strike twitching on the 777, have you heard anyone on this forum protesting that it took his flying skills away ?)
As for looking at the wing tips, you're quite welcome to try that technique on a swept-wing jet...and the top of instrument panels are not reliable for giving you an horizontal reference...and when you do not have a horizon, like in a mountanous area, or in fog or against a misty sunrise/sunset, what will be your reference for wings level ?
That's why a long time ago I was instructed to watch horizon, airspeed and ball-and-needle during the flare (that was on a DC-4, mind you...) and I've kept that technique through all my later airplanes, of which the 'Bus is only the latest in a long line and it is no different.
But it is in the minds of a lot of haters, so they yell words like *roll rate* like a magical spell...Had they just stopped to think of it, the amount of lateral yoke you'd input is just that :how fast the airplane is going to roll, then, because physics take over,a turn is initiated...the beauty of it is that you won't be normally using your rudder...
Now I ask you, where is the difference ?
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Lemurian
I think the responses prove my point. Within each of my statements I allowed a wide range of possible conclusions; I don't think I changed any minds, nor was I intending to. I've yet to see a truly objective position, and it cannot be because the two "types' are just too identical, and the partiality depends solely on training, or Company equipment.
Bottom line: The Hamburg incident where Captain doesn't "see" FP input a 14 degree left roll until the very best he could salvage was sparks on the runway and a shed winglet. With duplicative controls, moving in unison, same result? My feeling is no need to visit the shop. And if that is correct (it may well be wrong), one type is at least some of the time, a single seat A/C.
Bottom line: The Hamburg incident where Captain doesn't "see" FP input a 14 degree left roll until the very best he could salvage was sparks on the runway and a shed winglet. With duplicative controls, moving in unison, same result? My feeling is no need to visit the shop. And if that is correct (it may well be wrong), one type is at least some of the time, a single seat A/C.
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Airfoilmod - at the risk of going off topic (that incident's in another thread), as I understood it we weren't 100% sure of what caused that incident yet - I was given to understand that a considerable component of that roll was in fact a heavy gust that augmented the left roll that was input. Though in any case the question there was whether the Captain should have allowed the FO to continue that approach given the unfavourable weather.
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Point well taken. However, if the Luft Kapitan hadn't given the landing to FO, why shouldn't he? Is he concerned it's beyond her skill level? Fair enough, but if it's because he's uneasy about his ability to "I have it" instantly, we're back to the original question. And if that is the case, does that A/C not need four bars per side?
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That's what the override switch on the stick is for, and if he didn't feel the need to use it before the upset occurred, it's a question only he can answer.
Should really take this discussion to the relevant thread though.
Should really take this discussion to the relevant thread though.
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Read today in La Prensa, a Honduras newspaper, that a team from ICAO will be evaluating Toncontin airport for a possible reopening and usage by regular airliners. It is expected that they start their assesment tomorrow. After their report is issued, all interested parties will hold a meeting to determine how they will procceed with all the recommendations that ICAO would issue to enhance safety.
Also, read in another newspaper that United will cease operations to Honduras by September 2, but mentioning that it is because of fuel costs. They fly the Tegucigalpa - Los Angeles route (well, it used to be from Toncontin).
Also, read in another newspaper that United will cease operations to Honduras by September 2, but mentioning that it is because of fuel costs. They fly the Tegucigalpa - Los Angeles route (well, it used to be from Toncontin).
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Found this for Toncontin in English (easier reading for all). Now its future is up to ICAO, they say it will take eight days
ICAO will decide Toncontin’s future
http://hondurasnews.com/2008/06/17/icao-will-decide-toncontin%E2%80%99s-future/
ICAO will decide Toncontin’s future
http://hondurasnews.com/2008/06/17/icao-will-decide-toncontin%E2%80%99s-future/
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Even though Taca had the only two accidents in the last decade landing at TGU they will gain from shutting down to airline jet operation. Their commuter flights will be the only flights, other than other Honduran commuters allowed to operate, so they won by having the accidents if their influence with Honduran politians influences the ICAO to not allow jet airliners to land. I have been informed that Taca has a big influence on Honduran government officials so don't expect TGU to open to US carriers.
I think it is sad that a government can allow this to happen. Honduras should take ICAO's decision and not let politics for personal gain take over. ICAO should not be influenced by Taca's influence with the politics of Honduras.
If TGU shut down all operations to jetliners landing with a tailwind wet on 02 the problem is fixed. Tell Taca they have to go to the alternate like everybody else. Also do not land long like the last two accidents they had.
Once again, no US carrier has had an accident at TGU in 20 years. Only Taca had two.
I think it is sad that a government can allow this to happen. Honduras should take ICAO's decision and not let politics for personal gain take over. ICAO should not be influenced by Taca's influence with the politics of Honduras.
If TGU shut down all operations to jetliners landing with a tailwind wet on 02 the problem is fixed. Tell Taca they have to go to the alternate like everybody else. Also do not land long like the last two accidents they had.
Once again, no US carrier has had an accident at TGU in 20 years. Only Taca had two.
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My posts have probably been lost in the posts but I landed there almost 600
times in a B757 with absolutely no problem. I did follow the rules and landing on 02 with a wet tailwind of 5 knots was forbidden. My caluculations of their landing with the help of some Airbus friends showed they needed another 500 meters to land with the 1% downslope with the 10 knot tailwind wet. Now they want to own TGU and not let us in?
times in a B757 with absolutely no problem. I did follow the rules and landing on 02 with a wet tailwind of 5 knots was forbidden. My caluculations of their landing with the help of some Airbus friends showed they needed another 500 meters to land with the 1% downslope with the 10 knot tailwind wet. Now they want to own TGU and not let us in?
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As things have been managed after the accident, it just seems that TACA owns Honduras, just like bubbers mentions it.
Wonder about the accident investigation team that first took over the whole investigation? Well, it was composed of people from TACA and El Salvador, called themselves a "specialized team". That incorrect procedure was brought up to the attention of everybody, and I think that changed right after the people started to ask if that was "already arranged".
Wonder about the accident investigation team that first took over the whole investigation? Well, it was composed of people from TACA and El Salvador, called themselves a "specialized team". That incorrect procedure was brought up to the attention of everybody, and I think that changed right after the people started to ask if that was "already arranged".
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Usually the weather was fairly predictable so rarely cancelled flights unless a hurricane was approaching or a tropical disturbance. Once we cancelled for two weeks when heavy smoke in the valley restricted visibility. Many times I had to hold for an hour for visibility to get to minimums. Only a few times did we end up at an alternate. A few times we delayed flights because 5km was required to land and wasn't expected until afternoon. When we flew the B727 there we couldn't land on 20 because of go around performance so diverted a lot more than the B757 because of the 5 knot tailwind rule.
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What about RESA or EMAS?
Hi folks,
I'm just wondering, what about having an ICAO standard R.E.S.A. or better an IFALPA standard RESA at TGU (240mt suggested, but improbable at that airport..) or at least an EMAS?
Do you think that probably helped some way?
We should propose Runway Safety Actions while waiting for the TSB accident report.
Happy landings.
I'm just wondering, what about having an ICAO standard R.E.S.A. or better an IFALPA standard RESA at TGU (240mt suggested, but improbable at that airport..) or at least an EMAS?
Do you think that probably helped some way?
We should propose Runway Safety Actions while waiting for the TSB accident report.
Happy landings.
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Pick one for Toncontin (sorry for long post)
Currently, there are three alternatives to ILS. These are, first, variants of GPS; second, the Microwave Landing System (MLS) and third, the Transponder Landing System (TLS). Note that other than the military system mentioned, the GPS applications are equally achievable by Europe’s Galileo system, Russia’s GLONASS and other regional satellite navigation systems now being developed by China, India and Japan.
Landing Alternatives
LAAS. Called the Local Area Augmentation System (LAAS) by FAA, the Ground Based Augmentation (GBAS) by ICAO and GPS Landing System (GLS) by some operators, the concept uses four or five high-accuracy GPS receiver stations spaced around the airport to continuously and very precisely monitor the incoming GPS satellite signals to derive their individual GPS positions. These positions are then compared to the exactly surveyed locations of the receiver stations, to determine the error in the "raw" GPS positions. Any differences between the raw GPS and the surveyed locations is then processed and transmitted via a VHF data link to the aircraft as an accuracy correction. This is applied to the aircraft’s GPS, which then sends the corrected position to the aircraft’s flight management computer, and then to the pilot’s displays.
Unlike ILS, LAAS/GBAS is immune to reflections and is therefore potentially capable of supporting closer approach spacing and the elimination of taxiway "Hold" signs. However, many years of extensive testing did not completely eliminate issues of signal reliability and overall integrity, causing FAA to withdraw its earlier intention to adopt the system as its future ILS replacement across the National Airspace System (NAS). LAAS manufacturers Honeywell and GM Merc A/S, of Denmark, are now understood to have overcome the earlier issues, and both companies are finalizing the development of FAR 171-compliant "non-federal" variants of FAA’s full LAAS specification, which they expect in 2009 to certify to CAT I standards.
Honeywell prototypes are under evaluation in Germany, Spain, the United States and Australia, where Qantas 737s have been equipped, while a GM Merc system is installed at Norman, Okla., and used for FAA and United States Air Force tests.
France’s Thales is planning to upgrade its system at Toulouse, where it is used in the Airbus test program. However, no plans had been announced to further develop the LAAS ground stations to meet CAT II or III standards, reportedly requiring significant investment, although Boeing has investigated hybrid LAAS/IRS/FMS combinations to achieve the same result.
SCAT-I. An early development in FAA’s original LAAS project was the basic, low cost, Special CAT I (SCAT-I) system. Although subsequently overtaken by a later, more sophisticated FAA specification, SCAT-I used a similar configuration and provided similar guidance. The equipment has since been reintroduced by Norway’s Normarc, a component of Northrop Grumman subsidiary Park Air Systems, and has been approved by the European Aviation Safety Agency as meeting ICAO CAT I performance requirements. However, SCAT-I is not signal-compatible with LAAS, and requires unique airborne receivers built by Universal Avionics.
Naviair, the privatized Norwegian Air Navigation Service Provider (ANSP), plans to install 25 Normarc systems at "difficult" airports used by commuter airlines. Typically, these will serve remote coastal and inland settlements, such as the first installation at Bronnoysund, where surrounding high ground would make ILS impractical due to multipath effects.
JPALS. At the other end of the spectrum is the Joint Precision Approach and Landing System (JPALS), an advanced LAAS variant to meet the requirements of the U.S. military, and particularly the U.S. Navy. To be built to much more demanding specifications than civil systems, the Navy’s JPALS is intended to provide all weather, fully automatic landing guidance on aircraft carriers to manned and unmanned aircraft, with less sophisticated systems being produced for land installations, compatible with both civil and military GPS signals. Portable tactical variants are also included in the Pentagon’s projected $1 billion program.
Under separate contracts, more than 13,000 manned and unmanned aircraft are expected to be installed with JPALS-compatible avionics. The JPALS ground station contract award was expected to be announced in May, following competitive bids from Honeywell and Raytheon.
WAAS. The fourth GPS system that is starting to attract attention in the landing guidance community is FAA’s Wide Area Augmentation System (WAAS). Extensive testing and analysis of a massive collection of WAAS data by FAA’s Atlantic City, N.J., Technical Center showed that, as a result of progressive signal processing updates and the introduction of two new high-altitude geostationary satellites optimized for NAS coverage, WAAS guidance accuracy had become comparable to CAT I ILS.
Recent flight tests by Eurocontrol, using Europe’s equivalent EGNOS GPS augmentation system, have produced similar results. And while FAA officials are cautious about describing WAAS as a CAT I precision approach aid, the agency has nevertheless published WAAS approach procedures with 200-foot decision heights for several major airports, with more to follow.
This raises some intriguing possibilities. Since WAAS requires only an airborne receiver and no ground facilities, it offers the potential of a 200-foot decision height approach aid to literally thousands of airports that could not afford ILS, and have only been able to offer an NDB or VOR non-precision approach to much higher limits. As well, WAAS could avoid the ongoing maintenance and other costs of a currently installed ILS, or avoid the investment in a new or replacement system.
MLS. Some may be surprised to see MLS in this overview, since it is often thought to have been superseded by GPS. In fact, MLS is the only current ILS alternative to be certified to provide CAT II and III guidance, and Thales CAT III systems are installed at each end of London Heathrow’s two main runways. In turn, British Airways A320s and A321s are approved for CAT IIIb landings at Heathrow.
Like GPS, MLS is immune to signal distortion, which allows British Airways to gain closer spaced, and therefore additional, landing and departure "slots" in Heathrow’s high-density traffic stream, a major operational advantage. It is expected other airlines, including U.S. carriers, may install MLS for the benefits it provides today at Heathrow, and eventually at major European airports.
Since the availability of CAT III LAAS is unknown, other than possibly between 2015 and 2018, Eurocontrol is planning to replace CAT III ILS with MLS as traffic demands increase in the future.
TLS. A TLS ground station near the runway interrogates an aircraft’s transponder to derive its vertical and horizontal bearing, plus its range. It then calculates and transmits ILS-like localizer and glidepath signals to the aircraft’s ILS receiver, appropriate to the aircraft’s position relative to the desired runway approach path. Pilots then fly their ILS displays in the normal way.
TLS has FAR 171 approval for CAT I approaches, but its critical operational drawback is that only one aircraft can use the system at a time. It is reportedly successful in Alaska and other areas where landing traffic is light, but clearly has limitations for busier locations.
ILS is clearly going to be with us for many years to come — one FAA official predicted in 1990 that "ILS will be around for at least another 50 years." While that may be an exaggeration, the system’s worldwide proliferation, and its reliability and performance, coupled with the carriage of ILS receivers in virtually every civil aircraft, mean that the transition to a successor can only occur over a very extended period.
On the other hand, ILS signal reflection limitations would likely inhibit the expectation that in FAA’s NextGen environment, for example, landing traffic will flow as smoothly in low visibility conditions as it will in clear weather. At major high-density airports, therefore, it seems likely that ILS could be under pressure from both MLS and, when finally certified, CAT III LAAS. Or from some new technology yet to be revealed.
Landing Alternatives
LAAS. Called the Local Area Augmentation System (LAAS) by FAA, the Ground Based Augmentation (GBAS) by ICAO and GPS Landing System (GLS) by some operators, the concept uses four or five high-accuracy GPS receiver stations spaced around the airport to continuously and very precisely monitor the incoming GPS satellite signals to derive their individual GPS positions. These positions are then compared to the exactly surveyed locations of the receiver stations, to determine the error in the "raw" GPS positions. Any differences between the raw GPS and the surveyed locations is then processed and transmitted via a VHF data link to the aircraft as an accuracy correction. This is applied to the aircraft’s GPS, which then sends the corrected position to the aircraft’s flight management computer, and then to the pilot’s displays.
Unlike ILS, LAAS/GBAS is immune to reflections and is therefore potentially capable of supporting closer approach spacing and the elimination of taxiway "Hold" signs. However, many years of extensive testing did not completely eliminate issues of signal reliability and overall integrity, causing FAA to withdraw its earlier intention to adopt the system as its future ILS replacement across the National Airspace System (NAS). LAAS manufacturers Honeywell and GM Merc A/S, of Denmark, are now understood to have overcome the earlier issues, and both companies are finalizing the development of FAR 171-compliant "non-federal" variants of FAA’s full LAAS specification, which they expect in 2009 to certify to CAT I standards.
Honeywell prototypes are under evaluation in Germany, Spain, the United States and Australia, where Qantas 737s have been equipped, while a GM Merc system is installed at Norman, Okla., and used for FAA and United States Air Force tests.
France’s Thales is planning to upgrade its system at Toulouse, where it is used in the Airbus test program. However, no plans had been announced to further develop the LAAS ground stations to meet CAT II or III standards, reportedly requiring significant investment, although Boeing has investigated hybrid LAAS/IRS/FMS combinations to achieve the same result.
SCAT-I. An early development in FAA’s original LAAS project was the basic, low cost, Special CAT I (SCAT-I) system. Although subsequently overtaken by a later, more sophisticated FAA specification, SCAT-I used a similar configuration and provided similar guidance. The equipment has since been reintroduced by Norway’s Normarc, a component of Northrop Grumman subsidiary Park Air Systems, and has been approved by the European Aviation Safety Agency as meeting ICAO CAT I performance requirements. However, SCAT-I is not signal-compatible with LAAS, and requires unique airborne receivers built by Universal Avionics.
Naviair, the privatized Norwegian Air Navigation Service Provider (ANSP), plans to install 25 Normarc systems at "difficult" airports used by commuter airlines. Typically, these will serve remote coastal and inland settlements, such as the first installation at Bronnoysund, where surrounding high ground would make ILS impractical due to multipath effects.
JPALS. At the other end of the spectrum is the Joint Precision Approach and Landing System (JPALS), an advanced LAAS variant to meet the requirements of the U.S. military, and particularly the U.S. Navy. To be built to much more demanding specifications than civil systems, the Navy’s JPALS is intended to provide all weather, fully automatic landing guidance on aircraft carriers to manned and unmanned aircraft, with less sophisticated systems being produced for land installations, compatible with both civil and military GPS signals. Portable tactical variants are also included in the Pentagon’s projected $1 billion program.
Under separate contracts, more than 13,000 manned and unmanned aircraft are expected to be installed with JPALS-compatible avionics. The JPALS ground station contract award was expected to be announced in May, following competitive bids from Honeywell and Raytheon.
WAAS. The fourth GPS system that is starting to attract attention in the landing guidance community is FAA’s Wide Area Augmentation System (WAAS). Extensive testing and analysis of a massive collection of WAAS data by FAA’s Atlantic City, N.J., Technical Center showed that, as a result of progressive signal processing updates and the introduction of two new high-altitude geostationary satellites optimized for NAS coverage, WAAS guidance accuracy had become comparable to CAT I ILS.
Recent flight tests by Eurocontrol, using Europe’s equivalent EGNOS GPS augmentation system, have produced similar results. And while FAA officials are cautious about describing WAAS as a CAT I precision approach aid, the agency has nevertheless published WAAS approach procedures with 200-foot decision heights for several major airports, with more to follow.
This raises some intriguing possibilities. Since WAAS requires only an airborne receiver and no ground facilities, it offers the potential of a 200-foot decision height approach aid to literally thousands of airports that could not afford ILS, and have only been able to offer an NDB or VOR non-precision approach to much higher limits. As well, WAAS could avoid the ongoing maintenance and other costs of a currently installed ILS, or avoid the investment in a new or replacement system.
MLS. Some may be surprised to see MLS in this overview, since it is often thought to have been superseded by GPS. In fact, MLS is the only current ILS alternative to be certified to provide CAT II and III guidance, and Thales CAT III systems are installed at each end of London Heathrow’s two main runways. In turn, British Airways A320s and A321s are approved for CAT IIIb landings at Heathrow.
Like GPS, MLS is immune to signal distortion, which allows British Airways to gain closer spaced, and therefore additional, landing and departure "slots" in Heathrow’s high-density traffic stream, a major operational advantage. It is expected other airlines, including U.S. carriers, may install MLS for the benefits it provides today at Heathrow, and eventually at major European airports.
Since the availability of CAT III LAAS is unknown, other than possibly between 2015 and 2018, Eurocontrol is planning to replace CAT III ILS with MLS as traffic demands increase in the future.
TLS. A TLS ground station near the runway interrogates an aircraft’s transponder to derive its vertical and horizontal bearing, plus its range. It then calculates and transmits ILS-like localizer and glidepath signals to the aircraft’s ILS receiver, appropriate to the aircraft’s position relative to the desired runway approach path. Pilots then fly their ILS displays in the normal way.
TLS has FAR 171 approval for CAT I approaches, but its critical operational drawback is that only one aircraft can use the system at a time. It is reportedly successful in Alaska and other areas where landing traffic is light, but clearly has limitations for busier locations.
ILS is clearly going to be with us for many years to come — one FAA official predicted in 1990 that "ILS will be around for at least another 50 years." While that may be an exaggeration, the system’s worldwide proliferation, and its reliability and performance, coupled with the carriage of ILS receivers in virtually every civil aircraft, mean that the transition to a successor can only occur over a very extended period.
On the other hand, ILS signal reflection limitations would likely inhibit the expectation that in FAA’s NextGen environment, for example, landing traffic will flow as smoothly in low visibility conditions as it will in clear weather. At major high-density airports, therefore, it seems likely that ILS could be under pressure from both MLS and, when finally certified, CAT III LAAS. Or from some new technology yet to be revealed.