It's way to early to say but one of the threads seemed to indicate the helicopter pilot was told about the airplane and instructed to maintain visual separation. I used to be a military air traffic controller and that was fairly common practice but I wasn't aware this is something that happens in civil aviation where usually the margins should be much higher.
Crazy and sad. I guess we'll learn more over the next few days. Going into the water is maybe better than crashing on land. Hopefully some people make it.
It's very common for civilian ATC to instruct pilots to maintain visual separation, especially when they're both in the approach pattern. For airliners, TCAS gives an extra level of safety to guard against pilot errors. But I think many military aircraft lack TCAS.
> When visual approaches are allowed, controllers can tell pilots to maintain visual separation from other aircraft, so they don’t have to leave as much of a buffer as with an instrument landing (where it’s entirely on the controllers to provide proper spacing).
From an incident at SFO where a Luftansa plane was not allowed to perform a landing using visual separation at night, and therefore was delayed interminably:
TCAS is always active if your transponder mode dial is in such a position, so it always calls out other aircraft that are nearby and could pose a threat of mid-air collision. However, resolution advisories are inhibited near the ground. The last thing you want to be telling a pilot to do is to increase their descent when they're only a thousand feet above terrain -- this would at the very least trigger a more serious GPWS callout, the response to which is drilled into pilots during training -- pull up, directly into the path of the thing TCAS would want you to avoid. If the other aircraft also has TCAS equipped and enabled, and their RAs aren't inhibited, they will still get a climb instruction (both crews usually get opposite instructions in order to maximise the vertical separation).
Correct. At that altitude TCAS RAs were almost certainly inhibited. They might have gotten a TA.
On the tapes, the military helicopter was warned about the airliner. They replied that they had the traffic in sight and requested to maintain visual separation.
Crazy and sad. I guess we'll learn more over the next few days. Going into the water is maybe better than crashing on land. Hopefully some people make it.
EDIT: Found this: https://www.faa.gov/air_traffic/publications/atpubs/atc_html...