So when a pilot is flying along and suddenly hears a "Climb... Climb..." Resolution Advisory (RA) from ACAS/TCAS, we are trained to immediately climb to avoid a collision with another aircraft.

There is a reporting requirement in NTSB 830 which states (bold added by me):

49 CFR 830.5 - Immediate notification

The operator of any civil aircraft, or any public aircraft not operated by the Armed Forces or an intelligence agency of the United States, or any foreign aircraft shall immediately, and by the most expeditious means available, notify the nearest National Transportation Safety Board (NTSB) office when:


(10) Airborne Collision and Avoidance System (ACAS) resolution advisories issued either:

(i) When an aircraft is being operated on an instrument flight rules flight plan and compliance with the advisory is necessary to avert a substantial risk of collision between two or more aircraft; or

(ii) To an aircraft operating in class A airspace.


So my questions are:

  1. Is the phrase "compliance with the advisory is necessary to avert a substantial risk of collision between two or more aircraft" defined somewhere or is there any guidance to say when the report is required? I.e. is it anytime that we get an RA (even if we visually have the aircraft in sight), only if we actually respond to an RA, or is it if the two airplanes get within a certain distance from each other?
  2. When a report is required, how do we report it and what information is required? Is there a form that needs to be filled out?
  • 1
    $\begingroup$ I would expect "immediately and by the most expeditious means available" means a phone call. If possible even while still in flight or indirectly via dispatch, immediately after landing at latest. NTSB will want to secure ATC recordings, and if possible CVR or QAR data from both aircraft and these would be overwritten before anybody got to process any form. $\endgroup$
    – Jan Hudec
    Commented Feb 28, 2014 at 19:22
  • $\begingroup$ Of course ATC can make phone call easily, so the supervisor on duty should be the first to call NTSB, but they want the pilots to do so as well in case ATC for any reason fails to do so. $\endgroup$
    – Jan Hudec
    Commented Feb 28, 2014 at 19:25
  • $\begingroup$ @JanHudec Really? While in flight? Do you have a reference for that? Also, if we have to call it seems like they would be getting a lot of phone calls for this.... $\endgroup$
    – Lnafziger
    Commented Feb 28, 2014 at 21:08
  • 1
    $\begingroup$ @JanHudec Okay, I agree that's how it reads but I'm looking for a more official answer which is why I asked the question in the first place! :) $\endgroup$
    – Lnafziger
    Commented Feb 28, 2014 at 21:38
  • 1
    $\begingroup$ That's why I only commented. $\endgroup$
    – Jan Hudec
    Commented Feb 28, 2014 at 21:40

1 Answer 1


Well, #2 is actually surprisingly easy. At the top middle of the NTSB website, under "Other ways to Contact NTSB" there is an innocuous-looking link that says "Submit a TCAS Notification" (which has you send an email to [email protected]). Personally I'd follow that up with a phone call to the appropriate regional NTSB office as well, just to be sure you've discharged your obligation under NTSB 830.

The minimum required information for NTSB reporting is described in 49CFR830.6:

  • Type, nationality, and registration marks of the aircraft;
  • Name of owner, and operator of the aircraft;
  • Name of the pilot-in-command;
  • Date and time of the accident;
  • Last point of departure and point of intended landing of the aircraft;
  • Position of the aircraft with reference to some easily defined geographical point;
  • Number of persons aboard, number killed, and number seriously injured;
  • Nature of the accident, the weather and the extent of damage to the aircraft, so far as is known; and
  • A description of any explosives, radioactive materials, or other dangerous articles carried.

There is also a FAA website (www.tcasreports.com) which pilots are encouraged to use for reporting TCAS events - this site is not connected with the NTSB, and would not seem to cover that reporting requirement, but including the information that site asks for in your report to the NTSB would probably be helpful as well.

For #1 things seem a bit murkier: I too could not locate anything from the NTSB or in FAA AC 120-55C that clearly defines "necessary to avert a substantial risk of collision", but broadly I would imagine any Resolution Advisory (RA) is reportable, while Traffic Advisories (TA) would not be.
(The reportability of RAs would seem to be doubly true if you're operating in IMC, where you have no chance of visually assessing the hazard -- Complying with an RA there would seem essential to me.)

Note that AC 120-55C does allow a pilot to disregard a TCAS RA if they're certain that they have visual contact with the aircraft causing the RA - but it also cautions that it's difficult to be that certain:

Unless it is unequivocally clear that the target acquired visually is the one generating the RA and there are no complicating circumstances, the pilot’s instinctive reaction should always be to respond to RAs in the direction and to the degree displayed.

Presumably in a case where you're operating in VMC, it's "unequivocally clear" that you're looking at the aircraft responsible for the RA, and it's "unequivocally clear" that the traffic does not pose a substantial risk of a collision then following the RA is not "necessary to avoid a substantial risk of a collision" (i.e. you wouldn't have to report the incident).
I'd err on the side of reporting those events anyway though: If nothing else it serves to make the NTSB aware that something happened, and if they see a particularly large number of "somethings" in a given area they may take that up with the FAA to try to isolate and address possible underlying causes...

  • $\begingroup$ For #1 I was thinking of the times where I have the other airplane in sight and am maintaining visual separation but get an RA. Doesn't seem like it should warrant a report... As far as #2, I would really like to know if that satisfies the reporting requirement or not. An email is pretty immediate! :) $\endgroup$
    – Lnafziger
    Commented Mar 1, 2014 at 14:55
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    $\begingroup$ That link on the NTSB's website has been moved to the top middle of the page, under "Other ways to Contact NTSB". $\endgroup$
    – Lnafziger
    Commented Apr 5, 2015 at 2:02

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