What decides if additional GA thrust required

[mfclearner]

Certain places b737 QRH or supp procedure says If additional go–around thrust is desired(eg. “No Engine Bleed Landing.”)

Now how does one decide if additional go around thrust is desired?

[Wizofoz]

Climb- limit weight excedence would be one example.

Commanders discretion in a Hot, High and/or heavy scenario possibly another.

[mfclearner]

Wizofof could you please elaborate your answer I can't think of any scenario why one would takeoff with cilmb limit weight exceeding. Maybe I didn't understand what exactly you meant by climb limit weight exceedance. Sorry about it.

[Wizofoz]

Sorry, should have specified LANDING climb limit weight.


Landing Climb limit weight is actually a landing/go around consideration.

It's the maximum weight at which the minimum required climb gradient required for go-around can be achieved in the event of an engine failure during go-around.

If this was limiting, extra thrust by going bleeds-off may allow a higher landing weight.

[mfclearner]

Thanks alot very well explained. So one has to use ''Landing Climb Limit Weight'' table from performance dispatch section. But again my question would be... won't dispatch take into account landing climb limit weight?
Or this is just in case there is sudden increase of OAT at landing airport? Or your Non Normal is forcing you at airfield which is having high PA and/or OAT

[Checkboard]

Now how does one decide if additional go around thrust is desired?
A large rock viewed from the front window?

[punk666]

I know this is going to sound daft but when would one even look at them tables?

I only use the non normal landing distance table in OEI situations in the sim and the TRI/TRE has been happy with that.

Just from looking at the PD section there is a landing field limit weight dry/wet and landing field climb limit weight.

Would appreciate it if someone could explain them a bit more.

[Denti]

Well, we use an EFB which gives a landing climb gradient both for flaps 30 and flaps 15. This allows us to do a decision based on current conditions what kind of approach we do (F15/30) and if we need additional thrust.

But even before we got the landing performance program it was easy enough to look it up on the landing performance tables.

[framer]

won't dispatch take into account landing climb limit weight?

I imagine that they take that into account for your landing weight at destination. But if you return to land at the field you've just departed from and are therefore heavy, that obviously won't work.
Feel free to correct me if I'm wrong, I'm just assuming.

[de facto]

FAA only sends ADVISORY circulars hence you will see many airlines are missing or not implementing potential safety issues.
Missed approach climb gradient(toga one engine/flaps15) is one that is calculated and taken into account by DISPATCH in JAA not by the FAA.(yes may limit take off weight,FAA doesnt like that, too expensive for their airlines).
Recalculating such a gradient as conditions may have changed(landing temp,weight,wing anti ice use..)and landing distance(runway change,tailwind increase,rain) by dispatch is another JAA rule but yet just an ADVISORY issue for the FAA....in the mean time overruns keep on going...

[john_tullamarine]

I imagine that they take that into account for your landing weight at destination.

That's one of the two .. the other being approach climb limited weight.

(a) approach climb limit is based on the approach configuration (wheels up, approach flap and OEI). See FAR 25.121 (http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/MainFrame?OpenFrameSet)

(b) landing climb limit is based on the landing configuration (wheels down, land flap and AEO). See FAR 25.119 (http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr;sid=72d8548008163c441f045f454485a65d;rgn=div8;vie w=text;node=14%3A1.0.1.3.11.2.155.17;idno=14;cc=ecfr). Both rules have changed a bit over the years - you can look up the changes at the FAA website (http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/MainFrame?OpenFrameSet) if you are really keen.

The AFM contains both of the these although it gets a bit confusing in some cases if one is hidden within the graphs and becomes transparent to the enquiring pilot.

That's also why the missed approach procedural sequence is as it typically is .. to get from landing to approach configuration for OEI capability.

if you return to land at the field you've just departed from

Then you might be looking at dumping, holding, or exercising command prerogative and landing overweight, keeping in mind that the design standards have a looksee at landing overweight but with reduced impact capability .. ie do it gently.

FAA only sends ADVISORY circulars hence you will see many airlines are missing or not implementing potential safety issues.

I suggest that all operators of reasonable repute will be monitoring FAA and/or JAR recommendations and acceptable means of compliance quite routinely.

One needs to keep in mind that the FAA regulations tend to be fairly prescriptive and that the ACs give the Industry one way of meeting the requirement in a manner which will be acceptable to the FAA.

It follows (and is so prescribed) that the ACs are not mandatory and that the Industry entities are perfectly entitled to do something else and then convince the FAA that that alternative is OK. Generally, it's just easier to go with the flow, of course.

That is to say, the FAA rules are along the lines of "here is the requirement .. now, you meet it .. and, by the way, here's an AC which gives you some guidance on how we'd go about meeting it .. but you do it however you choose .. just do it".

Missed approach climb gradient(toga one engine/flaps15) is one that is calculated and taken into account by DISPATCH in JAA not by the FAA

I think I'm missing something here. The design standards already have this requirement built into the AFM at certification so, when you check for landing WAT limits, you meet both the approach and landing climb gradient requirements.

Recalculating such a gradient as conditions may have changed

It follows from the above that this is covered also .. surely you are going to check landing weights if the conditions have changed from forecast when you get to destination/alternate ?

[de facto]

I think I'm missing something here. The design standards already have this requirement built into the AFM at certification so, when you check for landing WAT limits, you meet both the approach and landing climb gradient requirements.
Would that be true for higher than standard missed approach climb gradient?ie 2.5% and above?

I was referring to SAFO 06012 which was not disseminated to so called reputable airlines such as the famous 'runway overrun' American Airlines.
AA latest was in 2009 for which finally the NTSB strongly recommended the FAA to update the AC concerning pilots taking in account changing conditions,tailwind in that case/sim training.
I believe jar ops makes it a regulatory requirement to calculate landing distance in flight.

I have yet to be introduced to safo 06012 and this revised AC in my reputable airline as no such training has been given during sim sessions.

[rudderrudderrat]

I defacto,
Would that be true for higher than standard missed approach climb gradient?ie 2.5% and above?
Before commencing the approach, we have to calculate our engine out missed approach climb gradient using the current weather conditions, and adjust our DA accordingly (like Zurich) or refuse the Approach (like Naples Rwy 06 ILS Z). I'd be very surprised if you don't have to do that.

[john_tullamarine]

Would that be true for higher than standard missed approach climb gradient?ie 2.5% and above?

No. The AFM addresses the Design Standard WAT climb requirements only. Higher gradients required for operations are an operator responsibility. If a pilot's operator doesn't address such things then one should do something about it.

I was referring to AC91-79 and SAFO 06012 which was not disseminated

Clearly, I can't speak for what any given operator not in my ambit may do. However, it has always been the case that the Industry is responsible for keeping abreast of the rules .. while noting that the FAA may well send out documents from time to time. When I was in routine consultancy practice, keeping the AC library up to date was one of the routine admin pains.

I have yet to be introduced to safo 06012 and this revised AC

I'm a little confused. If you knew of the existence of these documents but haven't been provided them by your airline AND you consider them important .. why haven't you perhaps sourced them simply and directly on the net ?

SAFOs are available from the FAA website (http://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/safo/all_safos/).

In particular the specific SAFO you seek (2006 vintage) is at this location (http://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/safo/all_safos/media/2006/safo06012.pdf).

The AC (2007 vintage) is available at this site (http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/list/AC%2091-79/$FILE/AC_91_79.pdf).

.. or have I missed something along the way, perhaps ?

[de facto]

Rudderrat,

I do , most dont ..hence the safety issue of such ACs rather than a clear cut regulation by the JAA.
Im not provided with tools to change my DA.

Tullmarine,
[QUOTE][No. The AFM addresses the Design Standard WAT climb requirements only. Higher gradients required for operations are an operator responsibility. If a pilot's operator doesn't address such things then one should do something about it./QUOTE]

Exactly my point.
And how would one go about it?since the AC on the issue is just an ADVISORY?

Yes i do get most my docs from the NET and im surprised that airlines dont make them available,ie distribute this info in a regular basis.

[mutt]

Im not provided with tools to change my DA. We supply (aircraft specific) crews with the option to use a different thrust rating, hence achieve a greater climb gradient, hence lower the DA.... see Hong Kong.

We also dispatch aircraft based on their ability to achieve the missed approach climb gradient that we have chosen, not 2.5%. This does lead to payload issues, however its must cheaper than hitting the terrain.

Crews are expected to calculate their landing distance/weight inflight based on the ATIS, and they are not permitted to use the Actual Landing distance once inflight (only in Emergency), they must use the Planned Landing distance.

The FAA have wimped out on a lot of things by issuing AC's rather than FAR's, my personal favorite is Contaminated Runways.

Mutt

[john_tullamarine]

We all understand that it's not easy out in the real world. No easy answer for most of these problems when the beancounters appear to have the driver's seat in most considerations.

That's easy for me to say, I don't fly these days.

However, I still have the same sort of philosophical worries when it comes to maintenance and engineering matters with which I am still involved daily.

[rudderrudderrat]

Hi de facto,
I'm not provided with tools to change my DA.
There are no tools - you just read the limits on the approach plate which satisfy your performance on the GA.
e.g. at ZRH Rwy 28, wouldn't you check if you can achieve 4% or not - else use 2.5% gradient limits?
http://www.blackholes.org.uk/PP/ZRH28

[de facto]

Hi rudderrat,

I am aware of using the ViS/gradient linked to the DA.i operated into Innsbruck and zurich.
My issue is that you are going to an airport where the lower DA with lower vis rvr 550 has a published Missed approach climb gradient of 4%.
Now you calculate your perf (737 flaps 15 one engine toga)65 t LDW and get a 3% gradient.
You obviously cant use your lower DA and cant sart the approach if the actual RVR is 550,,, below the rvr for the higher DA.
Now my perf people tell me the one engine toga aint a regulation that the climb gradient is for all engine so i could use the lower DA.
This i dont accept..unless i get a balked landing procedure to clear the obstacles laterally if possible.

mutt,

And yet my airline keeps on sending the lower rating (24k) 738 to that destination if if i recommended them to use 26k initially while this issue is dealt with....

All crews in my airline do bust these minima..now tell me the FAA failed to put the point across to ALL the major airlines where these guys come from including the one for which we working for now?
The only ones aware of such are some JAA colleagues of mine..
Its an eye opener...

[john_tullamarine]

Now my perf people tell me the one engine toga aint a regulation that the climb gradient is for all engine so i could use the lower DA.

To which your question should be "now what should be my strategy should I lose an engine during the approach or miss" ? Pray tell, what might be their answer ?

If the flight standards view is as you have suggested then it is grossly flawed. The underlying basis of heavy aircraft operation is a single failure at any stage of the flight being recoverable and that includes OEI during the miss.

I would opt for a higher minimum to satisfy the OEI consideration .. a lot cheaper than the fallout from a CFIT. However, to land involves putting yourself into the area where you have no miss capability OEI .. this gets back to inviolate commital heights .. and then what do you do if some idiot blocks the runway ? Then it comes back to very rapid risk assessment of what might give you the best outcome. If you are AEO, then the miss becomes attractive, OEI and you are between a rock and a hard place.

Some days it just doesn't pay to get out of bed.

Does your airline pay any attention to corporate risk management ?

[de facto]

Allehluya Mr Tullmarine,

You understand me and the issue i have with my airline.
Now i forwarded them with all the info i could find and ...work still in progress months down the road...while aircraft still going there on 24k where only an empty aircraft could make the gradient....the birds on NOTAMS just adding to the issue.

They pay real well:E but this issue comes from unclear FAA rules/advisories i believe..
They are an#l about safety and yet this issue is still floating on the desk of some top level bureaucrats..maybe forever in the bin ....

[john_tullamarine]

this issue comes from unclear FAA rules/advisories i believe.. They are an#l about safety

Then, for God's sake man, get in there and ask the boss what is going to be his corporate flight standards answer to the inevitable question at the Inquiry into the crash.

Someone is going to the slammer and, depending on jurisdiction, it is likely to be either/and both the boss and the commander (although the latter may not have any interest in the Inquiry, of course).

The rules are clear -

(a) don't crash

(b) see (a)

The advisories are just suggested ways to meet the rules. What REALLY counts is not what the FAA says but what the judge at the Inquiry says and what penalties are imposed after the fact.

The cited management attitude is directly analogous to taking off on the basis of the AEO TODR case only .. don't need ASDA or TODR1 as we aren't going to have a failure ...

[rudderrudderrat]

Hi de facto.
Now my perf people tell me the one engine toga aint a regulation that the climb gradient is for all engine so i could use the lower DA.
I have read the same somewhere else (but I can't find the reference at the moment), and the same is true for us operating into OPO on the southerly runway (4.9%).

One argument is that we do far fewer GAs than take offs, therefore the chance of having an engine failure on the GA is more remote. The practical solution is to look at the engine out procedure for the take off case. If you suffer an engine failure on the GA (unlucky day) then advise ATC that you're unable to comply with the standard missed approach and follow your EFTO procedure.