"Alarmist question: How does anyone know this was a model rocket rather than some form of unsuccessful missile attack aimed at the plane? People who launch hobby rockets large enough to fly that high have to know the implications of launching them in a major airport's flight corridor."
Rcade - you are correct. I've been involved in rocketry since I was a kid and I also have my high power certification. I have a couple of issues with this story...
1) 4,750 feet is above the altitude of most hobby rockets, especially anything the general public can fly. It is possible to hit altitudes of a mile or so with a model but it takes some doing and larger motors than most people have access to. Also, a model rocket at that altitude would be coasting at a low velocity and probably arching over, about to deploy it's parachute.
2) A middle of the road high power rocket can hit altitudes like this; I have one or two in my fleet that can do that. However...anyone who's achieved certification (which is required to buy the motors) knows full well that to fly a rocket that weighs over 3 lbs and/or contains more than 62.5 grams of propellant requires an FAA waiver. The waiver will specify the time and location and maximum altitude permitted of the launch and a Notice to Airmen is issued so that both the air traffic controllers and aircraft in the area know about the launch and; if neccesary, the ATC will reroute traffic around the area. This system works very well and the FAA is generally great about working with rocketeers and rocketry clubs are very tough on members to make sure waivers are adhered to. A rogue individual with a certification might fly on their own but they would be well aware of the potential consequences of doing so without proper clearance and also would know that a high power launch is something that is noticeable both to people in the area on the ground and probably visible in the air. Not that there aren't dummies out there of course.
2) The pilot mentioned "20 miles". If he's correct, there are only a very few people in the rocketry community who can hit altitudes like this. It takes very large and expensive motors to achieve this kind of thing. The very elite people who can do this are also the ones who are extremely well aware of the regulations and who don't do stupid things like fly this kind of thing without FAA approval and anywhere in the area of active aircraft operations.
So, my hunch is that the pilot probably saw a jet contrail at a higher altitude that, with certain sun angles, can look like something entirely different. It could have been someone flying a rocket but doubtful (and the rocketry community will be buzzing about this and investigating as well); it could also be a terrorist attack.
But it is highly unlikely that it is someone with a model rocket that they purchased at Walmart or a hobby store.
