Re: NTSB investigating ATC request Southwest to intercept Ci
Formation flight= 100 feet vertically and 1 mile laterally of the lead plane.
Standard formation, yes. There's also non-standard formation also.
On the other replies, there sure is a good amount of pre-judgement going on based on few facts.
ATC I don't find any fault with. ATC can request a crew to anything; whether or not a crew complies is another thing.
The pilots......well, it depends how close they got to the Cirrus and what the dynamics of the situation were. Close enough to see two people inside could mean anything. I don't have that info yet. I fully agree that unbriefed formation flying
under normal circumstances is can be very dangerous. However, for all we know, ATC may have been thinking they had another Payne Stewart situation going on. Vectoring another aircraft to check on one isn't dangerous in and of itself IF the intercepting crew knows what its doing. It doesn't sound like it was sustained formation flight, and if the SWA crew were ex or current military, then they'd know what they were doing. Remember, this appears to have been a "one time check" pass-by, if Im reading it correctly; rather than the 737 forming up on the Cirrus and tagging along in route or close. Again, I'd need more info to make a judgement.
Have accidents happened doing this? Yes they have. The most famous being the accident that killed Senator John Heinz in April 1991, when the Piper PA-60 Heinz was a pax in had a nosegear extension problem. A departing Bell 412 saw the passing PA-60 and reported the gear appeared to be extended. PA-60 pilot did a low pass by the tower and they saw same. Bell 412 pilot offered to join up for a closer look and the PA-60 pilot accepted. During the join-up on the low side, the 412 collided with the PA-60, resulting in all fatal. In this case, none of the aircrew involved had any formation training, and the joinup for an extended detailed check of an aircraft is something you'd definitely want that for.
As far as the below; again, Id have to know the dynamics of what occurred before I can pass judgement on what is "formation flight" and what isn't in this case, in regards to (c). (b) wouldn't apply if indeed a Payne Stewart situation was going on. And (a) is pretty subjective, as formation flight in and of itself isn't a collision hazard. Can it become one quickly in close form? Sure. But the dynamics are what we need to know before sending the SWA crew to the slaughterhouse.
Sec. 91.111
Operating near other aircraft.
(a) No person may operate an aircraft so close to another aircraft as to create a collision hazard.
(b) No person may operate an aircraft in formation flight except by arrangement with the pilot in command of each aircraft in the formation.
(c) No person may operate an aircraft, carrying passengers for hire, in formation flight.