It is really amazing how things go full circle and if you wait long enough, history repeat itself… even in air traffic management terms. There will be some amongst our readers who still remember how the saga of air/ground digital link began in the late 80s, early 90s.
Back then, at about the same time, airline experts and air traffic management planners, independently of each other, came to some scary conclusions affecting their communications equipment.
ACARS (Aircraft Communications Addressing and Reporting System) was becoming an essential tool for the world’s leading airlines and with its increasing use came the specter of frequency congestion and an inability to access the service on a timely basis. In particular, Lufthansa was a big advocate of the need to solve this problem as soon as possible.
Of course we were still before 9/11 and the world economic crisis and traffic demand forecasts were showing a solid 5-6 % growth year on year. Air traffic control centers were already working at peak capacity and it was easy to see that even if various systems enhancements, including decision making support for the controllers, were introduced, beyond a certain traffic density and complexity there would simply not be sufficient talk time available for the controller to communicate with the aircraft teeming in their airspace. Some new features, like trajectory based operations and anything else requiring complex clearances, could not even be considered because of voice communications related safety concerns. Some States, under the leadership of EUROCONTROL, started work on air/ground digital link and CPDLC (Controller-Pilot Digital Link Communications), a system that replaces voice communications with text messages, substantially increasing the amount of information that can be safely exchanged between ground and air even in very dense and complex traffic conditions.
The answer to both problems was VDL Mode 2/ATN. Of course things did not just line up without problems, but that is another story which you can read here.
Experts saw the unique potential of the situation. CPDLC on its own may not have been enough to trigger airline investment but if things were combined and the ACARS and ATM communications problems were addressed and solved in one go, the business case would be irresistible. Theoretically…
If we now jump to the present and consider that air/ground digital link and CPDLC are still up in the air (sorry for the pun), that even the European Commission’s mandate is apparently not enough to start things moving, one may be excused for the question: is this whole thing still relevant?
In the new, connected world of IP, VDL (anchored in VHF radios) and ATN (which is not IP) look like dinosaurs that have somehow escaped the wave of extinction.
Airlines are now supplying their pilots and maintenance personnel with iPads, tablets are becoming the standard issue electronic flight bag and passengers are expecting the same connectivity for their gadgets in the aircraft cabin as they have in their living room. Even in-flight entertainment experts are scratching their heads because people want to use their own gear to watch movies instead of the seat-back displays that were installed at huge cost only to become obsolete almost overnight.
Of course ACARS is still around and VDL Mode 2/ATN is slowly moving ahead, but connectivity these days means IP….
By the end of 2012, more than 3000 aircraft world-wide will have IP connectivity of some kind and in ten years this is expected to grow to around 15000.
Passengers expect seamless connectivity and they could not care less about the complexities this involves. In continental airspace, ground based systems work well and these require only a small, fixed antenna on the belly of the aircraft. Coverage over remote areas and the world’s oceans require a more elaborate and expensive seat-up. Satellite communications is the name of the game there and this comes with a steerable antenna mounted on the top of the fuselage. Bristles, radomes and other protuberances on the fuselage are bad news and unfortunately the laws of physics limit the ability of designers to make antennas ever smaller.
Traditionally, satcom has been expensive but rates have been dropping recently as competition and data volumes grow. With thousands of aircraft connected and airborne broadband services becoming standard and several providers in the market, this tendency is likely to continue.
But here comes the interesting bit. Interesting at least for those of us, who have been around the cradle of nascent air/ground digital link. 9/11 and the drop in traffic growth had all but halted the drive to have digital link in place by the originally contemplated deadlines. What we see now is the rapid emergence of the connected aircraft, machines with a permanent broadband lifeline to the rest of the world, driven by passenger demand. The collateral benefits for airline operations are already visible and are being exploited to a certain degree. Now if we could only add ATC communications also…
Obviously safety of life communications need a more robust and secure link than what Joe will want to send his emails in flight… but the opportunity is here. The big question is: will the industry recognize the opportunity and at least provision the IP connectivity so that it can be turned into the air/ground digital link we have always dreamed of or will this opportunity also pass by and see us left with the barely adequate VDL Mode 2/ATN solution occupying the front row while passenger communications once again rush way ahead of the cockpit… as it has now?