TCAS RA

[RAT 5]

To seek opinions: This could be reflected by a/c type or company or personal technique.

TCAS RA. Some years ago on B733 CL the QRH was disconnect A/P if necessary and follow RA guidance. I say if necessary because the RA could have been "maintain V/S". This could be either in climb/descent/level flight. Note A/T stayed engaged.
B738 NG. The manoeuvre now is to disengage A/T also. When a Boeing pilot was asked about this the answer was "to be consistent with the manual flight = manual thrust philosophy."
It was suggested that at high level, especially, this introduced a threat. You get a "CLIMB RA", haul back on the elevator and forget to add enough thrust. No need to go into space, but I suspect some might be over zealous at the thought of near death, hence forgetting thrust. Speed decays to very fast to stick-shaker.
You get a "Descend RA". Same action except it has happened that in one event pax & C/A were pinned to the ceiling. Once again you forget the thrust and smash the Mmo.
Or after the death defying descent you level off, check your heart rate and blood pressure, but forget to add power for level flight.

All the above errors I've seen performed in the sim by experienced crews. If leaving A/T engaged was a good idea on B733 CL is it really an improvement in safety to disconnect it now in Boeing SOP's? What is other types guidance and do airlines differ? I feel there should be more thinking to this than just a simple philosophy about manual flight.

[heavy_landing]

Think it's to be consistent - autothrottle may be engaged, for example when in LVL CHG/FLCH modes in descent, but won't move to maintain speed if CLIMB RA issued.

[Romasik]

Airbus keeps Autothrust ON...

[de facto]

RAT 5,

There is NO need in a RA to HAUL up or to be pinned down ....it should be flown accurately but gently..especially at high levels.
I see no issue with having the AT off,if you can t increase or decrease pitch gently without maintaining your speed then well...back to basics...

All the above errors I've seen performed in the sim by experienced crews

Maybe its time your Airline changes its recruitment sim sessions and add a few basic maneuvers without FD(yes oh my Lord) to weed out the addicts and ones unable to perform a maneuver as benign as an RA...

[de facto]

Claybird

Join Date: Mar 2009
Location: Roaming
Posts: 87
As De Facto said (were you away, De Facto btw? Welcome back), why 'haul up'?

I had a brief millenium post crisis,but thank you

[nitpicker330]

Yes Airbus keep Auto Thrust on BUT you must turn off the FD's.

[RAT 5]

And it's not always the case that FD commands are to be followed, there's criteria for that.

Guys: I did not suggest that one should haul back or stuff forward. Of course that is wrong technique. What I'm asking, quite simply, is why it can be deemed more safe to disengage the A/T during an RA? You are executing a 'life saving' manoeuvre perhaps at high level. Some people will panic and react thus; as has happened in real life. Both hands on the elevator and input delicate control commands to keep outside the crash box while looking out the window. With that technique & A/T engaged, in most cases, thrust will then look after speed. My curiosity is why change a perfectly good procedure for dogma? Has it been thought through thoroughly? If it is not a technique used by all types is it the best technique? An RA is certainly not a type specific manoeuvre.

Ref the above: in B737's you do NOT follow FD commands in an RA. Or have I misunderstood.

[de facto]

In the 737 NG i fly, RA pitch guidance must be followed not the actual FD.
The fact remains that if people get all panicked in a sim session following an RA,which is a basic and simple maneuver then well if it ever happened to them in real life,id rather be seated in the back of a chinese bus...more comfy on the G load for sure,,maybe not the lateral one though
Seriously,i take an RA as a dumb gentle maneuver,follow the guidance and dont think too much of the other aircraft...ie dont freak out...i had one over greece,we all survived and Pax didnt notice as even the CA were not aware of what had happened.

If people react in such a way,well yes then in a more complicated scenario such as a gradual loss of pressure may end up as a screaming of emergency descent over the PA as described in another thread here.

As long as your aircraft flies and you have oxygen ,no reason to panic,ESPECIALLY during your own airline regular OPC,i find it quite unacceptable from pilots that RAT 5 described as 'experienced crews'.

One hand is plenty enough to pitch an aircraft up or down,i use the left as it is connected to the elec stab trim,how convenient.
The right hand is on the thrust levers as intended by boeing to adjust the thrust.

Both hands on the elevator

Why?? even if you decide to leave the AT engaged,at least have a hand on the levers for feeling feedback of what the AT is doing.no?
The only time i would have both hands on the elevator would during the windshear maneuvers with AT disconnect at full thrust for more accuracy of manual inputs.

[vilas]

RAT 5
Your SIM instructors are not properly briefing pilots before conducting the exercise. There is a difference between terrain avoidance maneuver and TCAS RA. The pitch change required to fulfil RA demand is maximum 2 degrees in cruise,While it increase to between 5 to 7 degrees at speeds below 200kt. It is calculated at normal handling inputs.If the pilots knew this they wouldn't pull back harshly on the controls. If there are multiple threats the RA reversal can take place. So just pulling or pushing to its limit in one direction can compromise safety.

[grounded27]

Might be enlightening to hear from someone who has actually experienced an RA, sort of similar to the first combat experince of a soldier. With a previous airline we had structural stress damage as a result. No time to think, react is the only resolution.

[de facto]

grounded27 Might be enlightening to hear from someone who has actually experienced an RA, sort of similar to the first combat experince of a soldier. With a previous airline we had structural stress damage as a result. No time to think, react is the only resolution.

Refer to post #11.

With a previous airline we had structural stress damage as a result.

I dont know if I should be laughing or crying,what did your airline do ?retrained all of its pilots?
Yes there is no time to wonder about,however there is no need to overreact.

[grounded27]

de facto

Yes there is no time to wonder about,however there is no need to overreact

I agree, but have you had this experience?

[vilas]

grounde27
When you are faced with real RA you will react according to your perception of the maneuver. If you are not explained the mechanics of the RA requirement all you have is panic and fear. You do not save yourself because you pulled back with all your sreanght. As I mentioned you may have multiple threats and pulling or pushing in panic will put you in another's path. At .8Mach yoy need pitch change of max 2 degrees. How many Gs you need for that?

[de facto]

From my post #11

..i had one over greece,we all survived and Pax didnt notice as even the CA were not aware of what had happened

I agree, but have you had this experience?

What is it in my above post that dont understand?

I had one following an aircraft flying through its cleared level.

[AerocatS2A]

Originally Posted by grounded27

I agree, but have you had this experience?

I have. It's a non-event. You know don't you that you have 5 seconds to react to an RA? That's a long time to get a pitch change of about 2º established. Allowing for a couple of seconds to react, that is about 1º/second, or about a third of the pitch rate used to rotate during take-off.

[de facto]

I have. It's a non-event

It does require post flight paperwork though.

Ref the above: in B737's you do NOT follow FD commands in an RA. Or have I misunderstood.

In a 'preventative action' RA,ie 'monitor verical speed',you do continue on your actual path via the FD and must NOT fly into the area of RA pitch symbol.

The 'corrective action' RA you must pitch as close as feasible to the RA pitch guidance and not follow the FD.

[RAT 5]

Thank you guys, for your input, and we are in violent agreement. I mentioned no more than a real event where, perhaps due to the panic factor, an RA "descend, descend NOW" caused occupants in the cabin to be bounced off the roof.

[exeng]

Grounded27

Flying in Nigeria for 4 years I have had 4 TCAS RA's. In each event I have complied smoothly with the TCAS guidance and I doubt the pax have ever noticed - certainly no adverse comments.

My last 'nasty' would have been an RA but I avoided the traffic before it became an RA by climbing at max climb power (no traffic above). I had a TA during the climb and had to change my underpants shortly afterwards. Just like the sim actually where the traffic is on the nose at 4 miles and a thousand below - then the TCAS shows 800, 600, 400 - not nice.

Complete and utter mess and I won't post details here because the issue is still being investigated.

Some Captains, by the way, thought that I should have waited for the RA before reacting - most agreed with my actions - however I do see the other point of view. I knew nobody was above me at the time which in somewhere like LHR, FRA or JFK etc you cannot be sure of.

[vilas]

RAT 5
"An RA is certainly not a type specific manoeuvre." When it comes to Airbus FBW I am afraid it is type specific. It is mandatory to switch off APs and FDs but keep the ATHR on. If you keep FDs on the ATHR will not go into speed mode and during cimb in case of Descend RA your speed will increase with possible pitch up from high speed protection activation jeopardising the escape.

[RAT 5]

Thanks Vilas: I'm still operating in 'low tech' a/c. Your info is an education. My comment was motivated by the object of the exercise being to miss the other guy in a smooth controlled manner if possible, and not withstanding that I thought all elevators worked the same.
Safe flying.