A TCAS question

[coracle]

As a controller in the London TMA had an interesting situation the other day.

I climbed a Luton OLNEY departure ( on a northerly heading ) to FL100 against a Luton inbound heading east for a downwind right-hand on Rwy26 descending on top to FL110.

As the northbound approached the inbound passing FL95 he said he had a TCAS R/A but never seemed to descend or climb. I think he had " reduced vertical speed" warning.

Basically what i am asking is a reduce vertical speed warning ( or instruction ) considered to be a TCAS R/A?

[Dr Esteban]

Answer to your question: yes.

A "monitor vertical speed" message is know as a preventative resolution advisory.

On the other hand, all "climb" and "descent" or "maintain vertical speed maintain" or "adjust vertical speed adjust" messages are called corrective resolution advisories.

Regards,
Doc

[dv8]

I have wondered about that too. More so from a correct TCAS RT response.
Now if you get a TCAS CLIMB, you advise ATC with 'TCAS climb resuming FL ...' etc

But when you get Monitor Vertical Speed what is the correct terminology to use?

[brimstone]

TCAS phraseology is designed to mark the specific point where responsibility for separation passes from the controller to the pilot when deviating from his ATC clearance by climbing or descending in response to an RA, and then back to the controller when the manoeuvre is complete. That's why it's simple and concise. For any other types of RA action plain language is sufficient.

[BOAC]

dv8 - I cannot really see any situation where responding to a TCAS ROC demand would affect ATC? You will still be climbing or descending to a cleared level, so the actual ROC would not bother ATC, who would presumably be aware of the other traffic and PROBABLY expecting you to adjust ROC anyway?

[Gary Lager]

Monitor Vertical Speed = no problem, no reversal of climb/descent will be reqd.
Adjust Vertical Speed = may require a reversal of climb/descent.

I am sure no-one on here is confused, but it is extremely important to recognise the difference between 'Monitor Vertical Speed' (a preventative RA) and 'Adjust Vertical Speed' (a TCAS 2 corrective RA). There has been at least one level bust in UK airspace due to confusion between the two, and crew misunderstanding of what is required of them: (answer: the same thing in each case - follow the V/S guidance!!)

1. Always follow TCAS guidance
2. Don't try and be clever
3. Notify ATC when able
4. Ignore their subsequent instructions unless TCAS has announced 'clear of conflict'
5. If you think you are visual with the conflicting traffic, see rule 1.

[Max Angle]

For reporting purposes it still counts as an RA and ATC should be notified and a report filed.