It looks like Boeing's AirLaunch proposal was pretty much a dead-end soon after it was initiated. I found no other articles reporting news on it after that March 2000 article (there were a couple of mentions of it in later articles, but they did not have any new info, they simply offered it as a possible solution to the military requirement for rapid launch).
The next substantive mention of AirLaunch was for AirLaunch LLC, which bid on the DARPA/USAF "Force Application and Launch from the CONtinental US (FALCON)" program. In order for them to use that name, Boeing must not have trademarked it.
You can learn a little bit from this 2003 article in retrospect. Note the references to Elon Musk and how cheap everything was supposed to be.
Aviation Week & Space Technology
December 8, 2003
Launching Smallsats
BYLINE: Frank Morring, Jr.
SECTION: SMALL SATELLITES; Vol. 159, No. 23; Pg. 50
DATELINE: Washington
Renewed interest in small satellites has sparked a low-key push by the U.S. military to develop a new generation of launch vehicles that can match the low-cost and flexibility smallsats afford, a capability those not bound by U.S. law and policy already find in the surplus ICBM fleets of the former Soviet Union.
Smallsats have long lagged the promise they offer of low cost and mission flexibility because it can cost more to launch a smallsat than to build it. With even the cheapest launch on an Orbital Sciences Corp. Pegasus going for $ 12-15 million, potential users have often preferred to pay more for their satellites to buy reliability that may not be present in a simple, cheap little spacecraft that meets the classic definition of a smallsat.
"There's sort of a rule of thumb that says you need rough equivalence between the spacecraft, the payload and the launcher," said Dave Thompson, president and CEO of Spectrum Astro, which has moved from building small satellites for the U.S. government to larger, more expensive spacecraft.
In Europe and elsewhere, smallsat builders have often turned to the former Soviet Union for that rough equivalence in cost between their spacecraft and their rides to orbit. Surplus ICBMs like the Eurockot and the Cosmos-3M are reliable and low cost, and their launch operations earn high marks from customers.
"The way they work is very impressive," said Sir Martin Sweeting, CEO of Surrey Satellite Technology Ltd. (SSTL). "You have a couple of dozen people, you launch the rocket, and everything goes and wham! There's none of this big six-month lead-in and thousands of people and everybody tuning everything to the last widget, and when something goes wrong the whole thing gets caught up. If it doesn't fail, you get delays and cost."
The Soviet-surplus option isn't available to satellites built by or for the U.S. military, NASA and other U.S. government customers, who are bound by strict technology export-control rules and buy-American policies. In the past, they have opted for the air-launched Pegasus and its ground-launched spinoffs, or for piggyback rides as secondary payloads on larger rockets. Now, however, development of a new class of small U.S. launch vehicles is being pushed by a shift in U.S. military-space doctrine to small "tailored" spacecraft and "prompt" launch (see story p. 52).
The Defense Advanced Research Projects Agency (Darpa) is well along on its Responsive Access Small Cargo Affordable Launch (Rascal) technology-development effort, which seeks to revive the 1950s-vintage mass injector precompressor cooling propulsion concept and push other technology for the first stage of a partially reusable two-stage-to-orbit vehicle (AW&ST Sept. 22, p. 48).
And just last month Darpa, the U.S. Air Force Space Command and the Air Force Research Laboratory issued the first contracts in its Force Application and Launch from the Continental U.S. (Falcon) development effort, which includes a dedicated smallsat launcher and hypersonic weapons technology that could lead to advanced launch vehicles later (AW&ST Nov. 24, p. 15).
Winners of the Falcon small launcher contracts were AirLaunch LLC, Reno, Nev.; Andrews Space Inc., Seattle; Exquadrum Inc., Victorville, Calif.; KT Engineering, Huntsville, Ala.; Lockheed Martin Michoud Operations, New Orleans; Microcosm Inc., El Segundo, Calif.; Orbital Sciences Corp., Dulles, Va.; Schafer Corp., Chelmsford, Mass.; and SpaceX, El Segundo. Andrews Space also picked up one of the hypersonic contracts, as did Lockheed Martin Aeronautics, Palmdale, Calif.; and Northrop Grumman Air Combat Systems, El Segundo.
Pending negotiation of contracts in the $ 350,000-540,000 range for launchers, and in the $ 1.2-1.5 million range for hypersonics, each contractor will have six months to produce a system definition study outlining how they would meet Falcon-program goals. The Pentagon wants a "responsive, affordable smallsat spacelift" vehicle ready by 2010 that can put a 1,000-lb. spacecraft in low-Earth orbit for less than $ 5 million. By 2025 it is looking for a reusable "Hypersonic Cruise Vehicle" that can deliver an unpowered "Common Aero Vehicle" loaded with 1,000 lb. of munitions to a target 9,000 naut. mi. distant within 2 hr.
SpaceX, a startup rocket company that dot.com millionaire Elon Musk is financing, has already won a contract to launch a "transformational" Pentagon smallsat on the first flight of its launch vehicle early next year (AW&ST Oct. 6, p. 31). In what the company no doubt hopes will be a self-fulfilling prophecy regarding the Pentagon development program, it has named the new rocket the Falcon. Musk's approach -- hiring engineering talent with his own money to build a simple vehicle -- has intrigued potential launch-services customers inside and outside the U.S. government.
"Elon Musk is going, I think, exactly in the right direction," said SSTL's Sweeting. "[The U.S. Defense Dept.] wants to have small, responsive satellites. They don't want to have big, expensive vehicles. He realizes that if he tries to compete in the open market he's going to have a tough time, because it will be difficult to meet the Russians. He probably could just about meet them, but he won't make much money out of it. But if you look at the internal U.S. market, he can afford to charge a little bit more and make money out of it, and still be a lot cheaper than the other U.S. counterparts if he sticks to the basic premise in the way he's doing it, and doesn't get seduced into the fancy bells and whistles mode."
Spectrum Astro's Thompson is less sanguine, arguing that "our customers all want very reliable launch vehicles, so the kind of money that the government needs to spend to develop highly reliable alternative launchers is not there.
"You have SpaceX and you have Rascal and you have some interesting guys out there, but look at the people who have failed," Thompson continued. "You had Beal that tried to develop an alternate launcher. He failed. You have Kistler, which has spent hundreds of millions of dollars, but we don't have a launch there yet. There've been several alternative launch companies which have failed. So we're going to stick to the tried-and-true guys."
Philip McAlister, director for space and telecommunications at Futron Corp., agreed that low-cost launchers are going to rise or fall on reliability. Those concerns drove up the launch price of Orbital Sciences' Pegasus, which he said originally cost about $ 6 million a flight.
"That is just what Elon Musk is saying he's going to launch the Falcon for," McAlister said. "So that's the way they started out. But then the Pegasus had a couple of failures, as all launch systems do, as all transportation systems do, as a matter of fact, and then the amount of oversight and the amount of quality control that the customer insisted upon increased significantly, so now the Pegasus doesn't cost $ 6 million anymore, and it's not Orbital's fault. It was an evolution primarily driven by the customer requirements."