I've been getting questions from many corners asking how it's possible that Air France 447, or any commercial aircraft for that matter, could cross an ocean without air traffic controllers knowing the exact location of the flight at all times?Right now the only ubiquitous way to have a real time track of an aircraft is with a traditional radar system over or nearby land. Oceans present a unique challenge to aircraft crossing without radar coverage, even though it is done without incident hundreds, if not thousands, of times per day.
Since the early 1990s, pilots have used a system called FANS (Future Air Navigation System) that uses CPDLC (Controller Pilot Data Link Communications) and the older ACARS (Aircraft Communication Addressing and Reporting System) in lieu of voice communication with ATC. The CPDLC runs on ground based and satellite communications via Inmarsat.
Pilots interface with CPDLC via Flight Management Systems (747-400), Datalink Control & Display Unit (DCDU) panels (A330/A340) or Multi-Function Displays (A380, 777 & 787) to send/receive position reports, emergencies, route/speed/altitude changes, enroute weather reports and oceanic crossing clearances.
While cutting down the workload for both pilots and air traffic controllers, CPDLC was never intended to provide live flight tracking over the ocean. Instead, aircraft report their position at demarcated waypoints along the oceanic crossing and tell controllers when they expect to cross the next waypoint.
I ask: If it can be done on our cell phones, why not for our aircraft?
Air France 447 made a radio call crossing intersection INTOL, before the ACARS fault message was received from the aircraft about 54 nm from intersection TASIL, though the exact location of the crash is unknown as crews have begun to locate debris.
This leads directly into the biggest leap in air traffic control technology since the system was first created in the 1940s. The Next Generation Air Transport System, or Next Gen as it's known, will see the implementation of satellite based aircraft tracking with the GPS, called Automatic Dependent Surveillance - Broadcast (ADS-B). ADS-B technology transmits the location of the aircraft to within a few hundred feet of accuracy to both ground stations and other aircraft, rather than the 1-2 miles of accuracy with traditional radar.
The FAA plans to roll out Next Gen and ADS-B over almost a decade or longer, with airlines and industry groups pushing regulatory agencies to both move up deadlines for aircraft equipage and provide additional financial incentives to outfit aircraft. The ground-based portion of the system is expected to be deployed by 2013, but aircraft outfitting timelines remain an open question.
Right now, the FAA is providing financial assistance to United and US Airways to equip 747-400s and A330s with ADS-B equipment for trial testing, respectively. US Airways will have ADS-B on 20 of 25 of its new A330-200s for Atlantic crossings into Philadelphia. United will install the system on 12 747-400s for testing on Pacific flights between San Fransisco and Australia.
Australia announced in March that it plans to require all aircraft traveling through its airspace above FL290 by December 12, 2013 to comply with ADS-B requirements. The new air traffic system will cover the continent, as well as significant parts of its oceanic airspace. Though the Australians scaled back the plan as it took into account the pace of ATC developments in both Europe and the United States.
As the entire world looks for clues to the cause of Flight 447, technologies that make long haul air travel into areas without radar coverage safer may find themselves at the forefront of the lessons learned. Even if it is found that the cause of the crash is unrelated, a global situational awareness of aircraft position can help speed search and rescue missions, as well as aid in future accident investigations.
Advanced air navigation technologies have come out of air disasters before. In 1974, the FAA mandated Part 121 operators to install ground proximity warning systems in the wake of several controlled flight into terrain accidents in the early 1970s and later expanded that requirement to even smaller aircraft over the last thirty years.
Could this tragedy be the spur for global ADS-B coverage?
on June 2, 2009 10:45 PM | Reply
For oceanic flight, ADS-B (broadcast) isn't used, instead, ADS-A (addressed) is used. For ADS-B to work, something has to be able to receive the message. ADS-A uses the same satellite link that the CPDLC link uses.
RADAR can only scan 200-250miles out from land. With some aircraft still doing position reports using HF (high frequency radio), and no satellite links, it is really hard to know where an aircraft is once it is more than 200 miles out from land. (at 500mph, that is 30 minutes into the trip)
Cell phones only work in populated areas. ADS-B only work in populated areas. Take a trip across the ocean and neither cell phones nor ADS-B will work. NexGen only works over land.
The FAA ATOP system relies on ADS-A and HF position reports, along with a good deal of smart guessing (using winds and speed from a flight plan to determine the approximate location of the aircraft). It works, but you still need to fly 10-50 miles in trail.
on June 3, 2009 12:01 AM | Reply
If a system capable of automatic position reporting is used, this will also make it possible to determine a lot earlier whether something is wrong with the flight.
For example, if the system would transmit a position report every few minutes and these reports stop flowing, ATC can then contact the aircraft.
If the aircraft responds, all good, if it does not, then the situation can be escalated a lot earlier than if waiting for the next radio call.
on June 3, 2009 1:15 AM | Reply
A question: why aren't CVRs and FDRs designed to float?
The Orange Boxes from AF447 might be deeper than the Titanic. It seems odd to me that they aren't designed to automatically detach and float. I realise that, depending on the circumstances of the crash, the detaching function might not work properly, and the recorders will sink because they are still attached to a larger piece of wreckage. But just as a general principle, couldn't they be housed in a buoyant casing?
I've spent the last hour googling and can find no reference online to this idea being discussed. Self-detaching recorders are mentioned, but there is nothing about designing them to float. It makes me think this is a really dumb question.
Can any of you experts shed any light on this one for me?
Much appreciated
Dan
on June 3, 2009 4:36 AM | Reply
Don't forget to differentiate between primary and secondary radar. Secondary radar, which requires transponders, is essentially the basis of ADS-B and is the type of radar normally used for ATC.
I think in this case the ACMS (aircraft conditioning monitoring system) proved it's worth and pointed to something being wrong immediately. Without this system, the search area would have been much greater and the search could have lasted weeks. When something goes wrong in over an ocean, the aircraft still needs to come down and there is also a matter of currents, which means that a search will always be required.
on June 3, 2009 7:50 AM | Reply
It's interesting that few people think to ask why a ship can cross an ocean without ship traffic controllers knowing its exact location at all times.
In fact, I've found that people are often surprised to learn that light aircraft often fly without talking to air traffic control at all, and without filing a mountain of paperwork with "the authorities." These people would very likely be appalled if they were required to file with the authorities before driving their cars across country.
I believe that the underlying reason for the difference is that people are afraid of flying, and want to believe that "someone (an authority, preferably one with a lot of power) is in charge."
Someone is in charge. That someone is the pilot. Smile, when you meet one!
On the specific topic of Search and Rescue, that's a secondary, not a primary function of ATC. Agreed, if aircraft continuously broadcast their position, it would be easier to find them (assuming the signal was received, perhaps by satellite). Then again, an airliner actually vanishing over a large ocean is a very, very, very rare event.
Turning to the NextGen rollout, it's remarkable that the ground equipment is to be rolled out first. ATC's primary role is traffic separation. If relatively low-cost equipment were put in the aircraft first, they would electronically "see" each other and be able to avoid each other, and we could have that in place inside 5 years if FAA allowed the equipment to be simple and with low certification requirements. Instead, the ground equipment is going in first, so that controllers will have the information before the crews in the cockpits. The air equipment is being specified to make it as dependent as possible on ground feeds, rather than direct automated position communication air-to-air. This looks like an effort to ensure that no-one ever questions the need for ATC services (after all, if the planes can "see" each other, why do they need ATC?). Meanwhile, we wait...
on June 3, 2009 7:56 AM | Reply
ADS-B would not have helped since it requires a receiving ground station and suffers from the same line-of-sight limitation as radars.
ADS-A (aka ADS-C) otoh is used today to track aircraft on oceanic flights. The cost and low bandwidth of satellite communications means that position updates are less frequent.
on June 3, 2009 9:34 AM | Reply
It seems to me that if one takes into account the cost of a search and rescue mission, the cost to an airline in lost revenues by an unwilling public to chance their luck with a particular model of equipment, the very real threat to Western democracies of sabotage, the central role that transportation plays in 21st century, that it is vital then that a mechanism/mechanisms be developed that allow early and full disclosure of catastrophic events like these. Is this a pipe dream or a necessity of our times?
on June 3, 2009 9:50 AM | Reply
Why cell phones can do it? Because they have receiving towers and bandwidth. The satellite link has limitations: high cost for the requested bandwidth. Check out the rates for calling an Inmarsat phone. Geostar satellites don't cover the polar routes but have otherwise the bandwidth.
One more thing: what would tracking have helped? The debris were found with the existing system. The pilot already has the means for calling Mayday but who's going to rescue them in the middle of the ocean? The other planes flying the same route can at best rely what they can see from several miles above the sea. Unlike ships they cannot stop and pick up stranded passengers.
The media frenzy is only in the first 48 hours and gets forgotten afterwards. Let's wait for the wreckage to be salvages and the report.
on June 3, 2009 12:03 PM | Reply
sad thats how the way works....always takes a tragedy to spur safety....kind of ironic.
on June 3, 2009 3:47 PM | Reply
Now, that's hardly fair. Enormous amounts of effort go into preventive safety. The thing is, we only hear about it when those efforts are unsuccessful. The fact that tragedies ALSO spur safety doesn't mean that tragedy is NECESSARY to spur it.
on June 3, 2009 7:56 PM | Reply
My husband and son perished in the SR 111 crash so I know quite a bit about electrical failures, arcing, fires and the such.
Simulater test showed that, had it been a mecanical DC10 and not a fly by wire MD 11, 70% of the things that happened would have been avoided or could have been controled.
It has since been known (for over 10 years) that it was only a question of time for a fly by wire plane to drop out of the sky.
Air france is renowned for disrespecting weather conditions and just flying into storms. Their last accident was overshooting a runway with an Airbut 340 whilst landing during a thunderstorm.
With the Swissair crash and this Air France one, the myth that planes dont just simply fall out of the sky, has been truly broken.
on June 4, 2009 1:32 PM | Reply
Franca, Very sorry for your loss. I totally agree with the fly by wire issues, esp. given the Airbus circuitry is totally ROHS compliant (no lead, leading to a situation termed 'tin whiskers' where abnormal unexpected growths close circuits in unprecented unpredictable ways). In an electrical storm this would be exacerbated. As for the carrier, all I will say is each flight carrier has it's own unique culture, flying fingerprint so to speak, which is very easy to research and I assume you had done so. There are exceptions of course in every culture, good and bad, but nonthe less a culture does exist, and is spoken of within the pilot community. I am sure everyone is going to be buttoned up tight on that issue right now.
On that note, I have flown a number of large carriers on extremely long flights and only recommend AF for the food served. Flight safety IMHO is KLM and well, OK, Lufthansa. I have experienced equatorial storms in flight, and they are always treated as extremely serious and dangerous situation, one where pilots detour 2 HOURS AND MORE worth of flight time for saftey. That's a lot of fuel in today's economy.
A lot of people are pushing back today that large carrier planes fly through extreme turbulence all the time. That is absolutely not true, only an arrogant lunatic or a pilot misled by bad electronics would do so. I wish these people who say that large carriers fly through storms all the time, would acutally be made to get on one and actually do so, so that we may never ever hear that dangerous crap again.
on June 5, 2009 3:20 AM | Reply
What on earth was this airplane doing in the midst of what –it is said- was a major storm?!?
I read in the press:
>
What about the following answer: because of the violent storm?
Sure, something went wrong, something failed, and it would be nice to know exactly why, but, really, the first question that came to my mind was: what on earth was a long hall airliner equipped with high tech com devices, weather radar, etc, doing in a violent storm?!?
And just a few hours into it’s flight, with plenty of options to re-route, even turn back, plenty of speed potential to escape?
Did the passengers of this airplane paid for that?!
Can’t this airline be trusted to prioritize security over other business pressures?
What on earth was this airplane doing in the midst of what –it is said- was a major storm?!?
Why don’t reporters ask this question?
what do specialists have to say?
I don't check this blog often, I would appreciate comments at pascal_bruyere@yahoo.com
Pascal.
France.
on June 5, 2009 9:51 AM | Reply
Consider unstoppable, blinding smoke in the cockpit as a possible hypothesis
Various arguments have been presented as to why Air France 447 was lost at sea. These include structural breakup, computer failure, sabotage, electrical failure, and an electrical fire. What has not been put forth as a possible explanation is unstoppable blinding smoke in the cockpit. I’m not suggesting that smoke in the cockpit is the answer. I’m only advocating that it is a possibility, one not previously offered, and no less plausible an hypothesis than any other. Let’s look at what is known.
Air France received a bomb threat several days before the crash on a different flight at a different airport. The aircraft was inspected but no bomb was found.
At 11 PM local time, the pilot sent a message that the he was flying though strong cumulonimbus thunderstorms. Other reports stated that the vertical speeds were as high as 100 miles per hour. Air France also said that the aircraft’s automatic reporting equipment reported a short circuit.
Ten minutes later, a series of automatic messages indicated that the autopilot had disengaged, stabilizing controls were damaged, and flight systems deteriorated.
At 11:13 p.m. the system that monitors speed, altitude and direction failed. The main flight computer and wing spoilers failed.
11:14 p.m. The final message indicates a loss of cabin pressure and complete system failure.
According to the DailyMail Online, the Spanish newspaper El Mundo reported that a transatlantic airline pilot reported seeing a flash of white light at the same time the Air France flight disappeared. “ ‘Suddenly we saw in the distance a strong, intense flash of white light that took a downward, vertical trajectory and disappeared in six seconds,’ ”
Sabotage, as with an on board bomb, does not always lead to destruction of the aircraft. In the case of Swissair 330, a bomb exploded on board. The aircraft remained flyable. The pilot attempted to land but could not see due to the smoke in the cockpit. His final sentences were that he could not see to land. His last words were “good-by everybody.” Similar events happened on at least two other aircraft, an Air Cubaña DC-8 and an Air Kuwaiti 737.
Short circuits inevitably lead to wire fires. In aircraft fires the aphorism, “where there’s smoke there’s fire” can as easily be re-stated as, “where there’s fire, there’s smoke.” Wire fires are notorious for generating copious amounts of smoke.
On average, there is one unscheduled or emergency landing in North America daily. Most aircraft land without incident. But In July 2007, a NASCAR corporate twin-engine aircraft crashed. It experienced a short circuit. The wire insulation burned and that led to a cry of “smoke in the cockpit.” The aircraft crashed two minutes later. A short circuit lead to the fire and smoke in the crash of Swissair 111. It’s crash, like the crash of ValuJet 592 that preceded it, began with the cry “smoke in the cockpit.” These three examples and many others can be found in a 16-page report listing aircraft in which smoke was a cause or a factor in aircraft incidents and accidents. (See: http://www.smokeinthecockpit.com/references/List-of-Some-Smoke-Related-Accidents.pdf )
Electrical failures can lead to blinding smoke in the cockpit. Contrary to a common perception, pilots cannot see when unstoppable blinding smoke enters the cockpit. Air France 447 signaled that it was loosing cabin pressure. When smoke invades the cockpit, the Federal Aviation Administration recommends that pilots depressurize the aircraft to force the smoke out. If the smoke were a one-time event, this procedure would likely work. However, when the smoke is continuous, depressurization cannot help. The pressure on the outside and inside of the cabin would be equalized. Continuous smoke would build up, blinding the pilots.
Let me reiterate. I am not stating that continuous blinding smoke brought down Air France flight 447. I am saying that continuous unstoppable blinding smoke in the cockpit is an equally worthy hypothesis to consider. For those interested in more information on the subject, you might want to read Air Safety Week’s overview of the unsafe condition of smoke in the cockpit: http://www.smokeinthecockpit.com/references/Air-Safety-Week-Smoke.pdf
You can also read a recent (May 21st) U.S. House of Representative amendment to the FAA Reauthorization Bill (http://www.smokeinthecockpit.com/references/GAO-Amendment.pdf) that requires the Government Accountability Office (GAO) to study the unsafe condition of unstoppable blinding smoke in the cockpit. For an in-depth article on unstoppable blinding smoke in the cockpit, see —
http://www.smokeinthecockpit.com/references/Blinding-Smoke.pdf
James P. Stevenson
Former Assistant Managing Editor
Air Safety Week
on June 5, 2009 11:19 AM | Reply
Too many hypotheses. No real answers. Mystery needs to be unveiled. Share your theories on Find447.com. The site will be launched this weekend and needs your input.
on June 5, 2009 2:09 PM | Reply
What about 24 hour live voice recordings and location monitoring
from cockpit automatically sent to its home base, not every half hour every second. Battery operated of
course in case of electrical failure.
on June 6, 2009 5:14 AM | Reply
AF447
Surely it is possible to have all airliners transmit the flight recorders' data to a remote destination in real time?
When the enormous sums of money spent to hopefully find the recorders after an incident such as this, not to mention trauma for families and possible quick updates for pilots flying similar aircraft are taken into account then surely such a system should be feasible and affordable?
Yes, it will take bandwidth, but storage will not be a problejm as data can be deleted automatically after every successful leg unless the airline requests otherwise.
A service like YouTube probably uses a lot more bandwidth than one which transmits data, not video
on June 7, 2009 4:58 PM | Reply
By hypotheses or not, we'll always try to fill in gaps. It's psychology. Usually, most ex post facto view does not tie together the speculation for whatever might be good (we cannot say that it is all drivel a priori). Hopefully, we'll be able to do that better with the new media.
So, going along with the mode, have you all noticed the use of 'coffin corner' of late? It's something that all passengers of modern jets ought to know about. Basically, certain situations cause the margin of error to be much smaller than we all would expect.
On one side, stall; on the other, breakup? We know more about the former; is information on the latter suppressed to keep us flying?
How do we get this known? Hey, NASA does not put astronauts aboard without serious training.
Ought there be some push for more testing with actual planes being subjected to real circumstances, beyond those contrived in the lab?
Money? It's easily within bounds of the monies involved with the stimulus thrust.
on June 10, 2009 1:44 AM | Reply
Tribute Video to Passengers of AF447 http://www.youtube.com/watch?v=9MW49uHuylE
on June 20, 2009 5:52 AM | Reply
Actually, ADS-B will work anywhere the ground/satellite infrastructure exists to support it. We put ADS-B in Alaska (Capstone Program) beginning in 2001, and it supports fully certified ATC services over large areas of the state that are no where near a radar OR a "populated" area. Because the ground systems (called GBSs) are inexpensive, lots more can be deployed than radars.