Digital Data Links and Future Air Traffic Control.

Air Traffic Control in the United States is generally facilitated by the FAA and its contractors through radar surveillance, Secondary Surveillance Radars that use the transponders aboard aircraft, and voice communications. The precise navigation and separation of aircraft is done through standardized procedures, and complex avionics both radio based and GPS based. The problem is, the actual control of the  aircraft is done via voice communications. And voice communications are an awful way to share information.


For one thing, one controller is typically controlling several aircraft. The controller has responsibility for a certain slice of the airspace, and all aircraft flying through his particular piece are his responsibility. As you can grasp from the tower controller at JFK airport above, there’s only a certain amount of time available on a voice channel for each aircraft to actually talk with the controller. That doesn’t even count the time the controller is coordinating his actions with other controllers for when he hands them off to another.

Outside of air traffic control, airliners also need to conduct extensive communications with their dispatchers back at the home office.  Weather updates, information on connecting flights, and optimal routes for economy are discussed, among other things.  One of the most important matters is OOOI, or “Out of the Gate,” “Off the Ground,” “On the Ground,” and “In the Gate.” You see, airline crews and flight attendants are only paid for time spent flying, not time spent sitting on the ground.  In the old days, airline crews would use a second radio to call in these critical points. And it occurred to some airlines that maybe, just maybe, the crews might fudge just a shade in their favor on some events. And so the airlines turned to the avionics industry for a technical solution. The result was ACARS, Aircraft Communications Addressing and Reporting System. Sensors around the aircraft would be able, for instance, to tell if the cabin doors were all closed, and the engines running. A very brief digital message could be sent over the radio (it sounds like a chirp followed by about a 1/4 second of static) updating the aircraft status to the dispatcher and airline operations center. In essence, it began as a time clock, letting the airlines know when they had to start paying the crew.

Piedmont was the first airline to adopt ACARS, but by the mid 1980s, it was in widespread use. And the airlines figured out a few other things as well. ACARS could send a whole host of information back to home. It also was a handy way of sending information to the airliner in flight. An airliner might be sending back its position, speed, altitude, route, fuel on board, engine performance at regular intervals, while dispatch regularly uplinked weather updates, pilot reports of conditions along the route, information concerning any delays, and  connecting flight information. All this could be done using extremely brief digital messages.

The FAA hasn’t been totally sitting on its hands. There’s a vast wealth of online tools for pilots to plan flights. The days of a huge Jeppeson case stuffed with paper charts are gone. Virtually every pilot today gets absolutely up to date charts, approach plates and airport diagrams on his iPad, either via the FAA or any number of online resources. But those resources are for planning the flight, or looking up information during the flight. Again, the air traffic controller still interacts with the flight crew via voice radio.

That’s sl0wly starting to change, particularly on long oceanic flights. VHF radio is essentially line of sight, with a range of about 200 miles for a high flying aircraft. Jets on long overwater flight instead use HF radio. But often times, HF radio audio quality is poor.  Instead, HF radio can be used to send data, or alternately, satellite communications through InMarSat can be used to transmit ATC message both ways.

The generic term is Controller-Pilot Datalink Communications (CPDLC). Boeing and Airbus both are fielding systems under the name FANS, Future Air Navigation System, and in addition to oceanic routes, its being adopted for use over parts of continental Europe. As yet, it is not in use in the continental US airspace. One suspects that it inevitably will be adopted at least in part. One great advantage that testing of CPDLC has shown is that it greatly reduces the volume of voice traffic for a given controller, by as much as 75%.  One example was the handoff from one controller to the next as an aircraft moves from one slice of the airspace to another.

Here’s a notional handoff as currently done by voice from an Air Route Traffic Control Center:

Oakland Center: United 345, contact Los Angeles Center on 134.45.

United 345: Los Angeles on 134.45, good day.

United 345://tunes radio to 134.45

United 345: Los Angeles, United 345 with you.

Los Angeles Center: United 345, roger.

With a CPDLC system, as the aircraft approaches the airspace boundary, the controller (or even the computer automatically) would  generate a digital message to the aircraft that would automatically interface with the airliner’s Flight Management Computer, telling the crew, automatically tuning the radio, and automatically generating a check in message to the new controller at Los Angeles Center, all reducing the workload of the flight crew, the controller, and reducing the volume of traffic on the voice network, allowing controllers to focus more on higher priority issues.

What’s interesting is this trend toward datalink control of air traffic is using modern technology to implement techniques that were first established as far back as the 1950s when the North American Aerospace Defense Command used the Semi-Automatic Ground Environment to control interceptor aircraft defending against potential Soviet bomber attacks.

Sea-Air-Space 2015 – US Navy V-22


NAVAIR has recently unvieled it’s plan for the COD version of the V-22 Osprey at the recent Air-Sea-Space 2015 expo in Washington DC. Via Navy Recginition:

Colonel Dan Robinson, NAVAIR V-22 Program Manager, gave the latest on U.S. Navy variant of the V-22. It was made publich in February this year that the U.S. Navy would procure the Osprey to answer its future Carrier Onboard Delivery requirements. As of now, the U.S. Navy is planning on procuring 48 Ospreys. The Osprey typical Navy missions will include:
– Sea Based Logistics (including COD)
– Personnel recovery (including SAR)
– Special warfare (with US Navy Seals)

A model of the Osprey in Navy colors was also on display:


The COD version of the Osprey will replace the venerable Grumman C-2 Greyhound which has been in US Navy service since the late 1960’s. While there’s no question a new COD aircraft is needed, the V-22, as currently configured has a range problem when comapred to the Greyhound.  NAVAIR is looking at increasing the range by increasing the size of the sponsons which house the main landing gear.

Grumman's C-2 Greyhound first flew on 18 November 1964.
Grumman’s C-2 Greyhound first flew on 18 November 1964.

Cutaway Thursday: Boeing YC-14

The Boeing YC-14 was a twin enigne STOL (short take-off and landing) transport aircraft that completed in the USAF Advanced Medium STOL Transport (AMST), basically an attempt to replace the C-130. The YC-14 was competing against the YC-15 (which evolved into the C-17) in the AMST program, which we covered here.


The YC-14 is currently on display that the Pima Air and Space Museum. You can learn more about the YC-14 here.

Prowlers and Pods

Spill just brought to my attention that the Marines have, for several years now, integrated the Lightening targeting pod onto their EA-6B Prowler radar jamming aircraft.

That pic is from 2007 or so. At that time, there wasn’t a lot of need for radar jamming in Iraq or Afghanistan. But in addition to being a world class radar jammer, the EA-6B is pretty good at intercepting tactical communications. One wonders just what techniques and procedures the Prowlers might have been using.

As an aside, that jet is from VMAQ-2, the Death Jesters. Back in  the days before the Tailhook ‘91 scandal, they were known as The Playboys- complete with the bunny on their tail. Now take a glance at the “CY” tailcode on this jet.

Beijing Air & Space Museum

Global Aviation Review has a fascinating photo essay on the Beijing Air and Space Museum. Located at Beijing University and sometimes called the China Aviaiton Museum, there’s a rare and unique collection of aircraft that those outside of China rarely get to see and it offers an interesting glimpse of Chinese aviation history.

Something you won't see anywhere else, a P-47 and across the way, a MiG-9.
Something you won’t see anywhere else, a P-47 and across the way a MiG-9.

The Beijing Air and Space Museum has one of the very few Northrop P-61 Black Widow:

Another unique exhibit featuring the Chinese built MiG-15 and MiG-17 with the Northrop P-61 Black Widow.

Head on over to Global Aviation Resource to take a gander at more of the Museum.

Fascinating stuff behind the Bamboo Curtain

The FAA Commemorates 9/11

This is from last year, but I just now learned about  it. And I’m told this is the permanent structure for approaches into Ronald Reagan Washington National Airport for GPS approaches.

FREEDOM approach into DC


As people gather at memorials on the 12th anniversary of the 9/11 terrorist attacks, one means of remembrance is written in the sky. Flights headed toward Ronald Reagan Washington National Airport use procedures and waypoints that commemorate the victims of 9/11 and honor U.S. soldiers who have served in Iraq and Afghanistan.

Aircraft flying in from the northwest use the FRDMM arrival, taking them over waypoints “WEEEE,” “WLLLL,” “NEVVR,” “FORGT” and “SEP11.” Flights from the southwest, use the TRUPS arrival and cross waypoints “USAAY,” “WEEDU,” “SUPRT,” “OOURR” and “TRUPS.”

Depending on the runway configuration, aircraft might pass through waypoints named “STAND” and “TOGETHER,” or “LETZZ,” “RLLLL,” “VCTRY” and “HEROO.”

The arrival sequences are part of the FAA’s Metroplex initiative, which is creating satellite-based procedures to bring greater efficiency to the airspace over several metropolitan areas around the country.

The FAA also published a “GARDN” fix over the area in rural west-central Pennsylvania where United Flight 93 crashed after passengers and crew members fought with hijackers for control of the plane, preventing it from reaching its intended target of Washington, D.C.

You can download the .pdf approach plates here.

Hornet Ball

Each year, each of the communities in Naval Aviation, hold a ball. One such community is  the West Coast F/A-18C/D Hornet and F/A-18E/F SuperHornet squadrons. The annual balls are  fun social occasions allowing the aircrew to dress up in their best uniforms and show off their ladies (or gentlemen, in this new age) in their finest. Speeches are made, and presentations on the state of the community by leadership and contractors given. And it is awards season, both for the best squadrons, and for individual achievement within the community.

In the last dozen or so years, one highlight of the community balls has become the videos various squadrons and even individuals put together for presentation. Here’s one.



Early on in the blog, we wrote about the development of the gunship, modified transport aircraft armed to provide fires to troops on the  ground. They’re very expensive aircraft (mostly because of their sophisticated sensor arrays) so there are only a relative handful in service.

The introduction of the C-27J in service had some folks hoping a “Gunship Lite” program could be developed to supplement (but not supplant) the current AC-130U.  For various reasons, including the cancellation of the entire C-27J program, that never came to pass.

But the need to bolster gunship numbers didn’t go away.  So the MC-130W “Dragon Spear”  was pressed into service. Originally intended to make up for losses in the special operations MC-130H community (clandestine delivery and retrieval of special operations forces), the MC-130W’s were in fact armed with sensors and weapons. A 30mm Bushmaster gun and ViperStrike missiles gave it a limited ability to attack enemy targets on the ground with great precision.

The armed mission was so pressing, the special operations mission was set aside, and last year, the “Dragon Spears” were redesignated AC-130W Stinger II.

The Air Force hopes to add Hellfire missile capability within the next year.  I’ve heard they can (or soon will) use the GBU-39 Small Diameter Bomb, but haven’t seen confirmation of that.

If you look closely at the pic above (click to embiggenfy) you’ll note not only the 30mm gun on the port side, but also the pylon outboard of the engine. That’s where the Hellfires will mount. The small turret under the nose radome houses the infrared sensor/laser designator.