Air Operations

Hi John, thanks for reply. No other reactions added. Could be non-existent in EUR then at this moment. Best regards.

One of the reasons (maybe the most common one) for pilots not following an RA is that the regulation includes the infamous "unless doing so ..." exception - but no guidance on it! Even instructors and examiners have few clues about how to make best use of it.

During initial implementation of TCAS there were still numerous false or nuisance alerts. Nowadays the system is much improved and working very well. So well, that it is against human nature to trust it completely. There may still be some unnecessary RAs, but it is still the lowest risk option to follow them.

Now, what would be valid reasons to ignore an RA?
1. The intruder transmits a wrong altitude: then the RA cannot be correct. Should be controlled to a very low probability by Air Traffic Control. When observing an aircraft at the wrong altitude (not always easy to detect), the controller would advise the pilot to correct the problem or to switch off Mode C.

2. There is an additional aircraft, not squawking Mode C or not squawking at all, but happening to be exactly in the airspace that TCAS advises to manoeuver in response to a valid threat. Extremely unlikely scenario.

3. A failure of the TCAS system, e.g. a programming error. Extremely unlikely following decades of operational experience and software improvements.

Can anybody suggest any other reason that has a high enough probability to be concerned?

This leaves us with the Human Factors problem: the knowledge is there, a lot of guidance for "FOLLOW THE RA" too, but the exception clause is misused for various reasons, including the lack of guidance on valid reasons for using the exception.

Train the Trainer, Check the Examiners!

Dear All,
Thank for the question and the answer.
Just take the opportunity to add another question about separation between HEL and airplane at stand or/and airplane during taxi. This is more a question for Airport OPS and AMS.
I am looking for EASA rules to have clear values of separation between and HEL (take off/landing) and a airplane at stand.
Same question for an HEL (take off/landing phase) other an airplane on the taxiway.
Thank you,
Nicolas

my air this best